[Mark[_14_]]

I'm trying to repair a Cossor 1045K Oscilloscope and would be grateful
if anyone could point me in the direction of the service / operator
manual. I can find a copy of the circuit diagram from www.mauritron.com,
but ideally I would like to get a copy of the full manual.

The CRT appears to be working fine as the X and Y position adjustments
work. When I connect the Y input to the built in 1V pk-pk AC test
signal the scope displays a vertical line, but the test signal itself
appears to be ok. Changing the timebase makes no difference to the
display and the output from TB OUTPUT is a constant 187V DC. The end
of a wire that is connected to the timebase switch has come loose, but
it is not clear to where the other end should be connected. If anyone
has a working example I would appreciate if they could tell me to
where this wire should be connected, it is the short black wire from
the bottom of the rotary timebase switch (the pin that also has a wire
to the 2 uF capacitor that is mounted on the switch and another red
wire connected).

Thanks,

Mark

[KeithR]

Mark wrote:
I'm trying to repair a Cossor 1045K Oscilloscope and would be grateful
if anyone could point me in the direction of the service / operator
manual. I can find a copy of the circuit diagram from www.mauritron.com,
but ideally I would like to get a copy of the full manual.

The CRT appears to be working fine as the X and Y position adjustments
work. When I connect the Y input to the built in 1V pk-pk AC test
signal the scope displays a vertical line, but the test signal itself
appears to be ok. Changing the timebase makes no difference to the
display and the output from TB OUTPUT is a constant 187V DC. The end
of a wire that is connected to the timebase switch has come loose, but
it is not clear to where the other end should be connected. If anyone
has a working example I would appreciate if they could tell me to
where this wire should be connected, it is the short black wire from
the bottom of the rotary timebase switch (the pin that also has a wire
to the 2 uF capacitor that is mounted on the switch and another red
wire connected).

Thanks,

Mark

Why on earth would you want to fix one of those things. They were a
crappy scope even in their heyday, you can do much better for a very
moderate price these days.

Keith

[Patrick Turner]

keithr wrote:

Mark wrote:
I'm trying to repair a Cossor 1045K Oscilloscope and would be grateful
if anyone could point me in the direction of the service / operator
manual. I can find a copy of the circuit diagram from www.mauritron.com,
but ideally I would like to get a copy of the full manual.

The CRT appears to be working fine as the X and Y position adjustments
work. When I connect the Y input to the built in 1V pk-pk AC test
signal the scope displays a vertical line, but the test signal itself
appears to be ok. Changing the timebase makes no difference to the
display and the output from TB OUTPUT is a constant 187V DC. The end
of a wire that is connected to the timebase switch has come loose, but
it is not clear to where the other end should be connected. If anyone
has a working example I would appreciate if they could tell me to
where this wire should be connected, it is the short black wire from
the bottom of the rotary timebase switch (the pin that also has a wire
to the 2 uF capacitor that is mounted on the switch and another red
wire connected).

Thanks,

Mark

Why on earth would you want to fix one of those things. They were a
crappy scope even in their heyday, you can do much better for a very
moderate price these days.

Keith

I chucked out a couple of veteran CROs recently yo stop myself ever
wasting time restoring them. As soon as i cleared the decks of this crap
and a trailer load of other un-mentionables some dude rings and says he
has a whole other pile of stuff he wants to donate to a good home.
So one lot of junk got replaced with another bigger lot, and including 4
more CROs, one of which is tubed, and runs far too hot so it is only for
emergencies tendered with reluctance.

Patrick Turner.

[bigwig]

On 14 Apr, 15:22, Patrick Turner wrote:
keithr wrote:

Mark wrote:
I'm trying to repair a Cossor 1045K Oscilloscope and would be grateful
if anyone could point me in the direction of the service / operator
manual. I can find a copy of the circuit diagram fromwww.mauritron.com,
but ideally I would like to get a copy of the full manual.

The CRT appears to be working fine as the X and Y position adjustments
work. When I connect the Y input to the built in 1V pk-pk AC test
signal the scope displays a vertical line, but the test signal itself
appears to be ok. Changing the timebase makes no difference to the
display and the output from TB OUTPUT is a constant 187V DC. The end
of a wire that is connected to the timebase switch has come loose, but
it is not clear to where the other end should be connected. If anyone
has a working example I would appreciate if they could tell me to
where this wire should be connected, it is the short black wire from
the bottom of the rotary timebase switch (the pin that also has a wire
to the 2 uF capacitor that is mounted on the switch and another red
wire connected).

Thanks,

Mark

Why on earth would you want to fix one of those things. They were a
crappy scope even in their heyday, you can do much better for a very
moderate price these days.

Keith

I chucked out a couple of veteran CROs recently yo stop myself ever
wasting time restoring them. As soon as i cleared the decks of this crap
and a trailer load of other un-mentionables some dude rings and says he
has a whole other pile of stuff he wants to donate to a good home.
So one lot of junk got replaced with another bigger lot, and including 4
more CROs, one of which is tubed, and runs far too hot so it is only for
emergencies tendered with reluctance.

Patrick Turner.- Hide quoted text -

- Show quoted text -

LOL, funnily enough this stuff is quite collectable. Mainly by people
who collect TEK or HP kit to laugh at. Seriously though you can learn
a hell of a lot rebuilding old scopes and test gear,it tends to be
built to be repaired. The old Cossor stuff is nice, built like a tank
check out this site, he may be able to help: http://www.thevalvepage.com/testeq/scope.htm

I do get a bit niggly when people rip a going concern to bits just to
use the trannys, tagstrips, sockets etc. They end up with a whole pile
of ****e and have learnt nothing in the process of destruction. Better
to repair it and realise its crap than make something that took up
3cuft of space into some great pile that really becomes a problem.
Matt

[KeithR]

bigwig wrote:
On 14 Apr, 15:22, Patrick Turner wrote:
keithr wrote:

Mark wrote:
I'm trying to repair a Cossor 1045K Oscilloscope and would be grateful
if anyone could point me in the direction of the service / operator
manual. I can find a copy of the circuit diagram fromwww.mauritron.com,
but ideally I would like to get a copy of the full manual.
The CRT appears to be working fine as the X and Y position adjustments
work. When I connect the Y input to the built in 1V pk-pk AC test
signal the scope displays a vertical line, but the test signal itself
appears to be ok. Changing the timebase makes no difference to the
display and the output from TB OUTPUT is a constant 187V DC. The end
of a wire that is connected to the timebase switch has come loose, but
it is not clear to where the other end should be connected. If anyone
has a working example I would appreciate if they could tell me to
where this wire should be connected, it is the short black wire from
the bottom of the rotary timebase switch (the pin that also has a wire
to the 2 uF capacitor that is mounted on the switch and another red
wire connected).
Thanks,
Mark
Why on earth would you want to fix one of those things. They were a
crappy scope even in their heyday, you can do much better for a very
moderate price these days.
Keith
I chucked out a couple of veteran CROs recently yo stop myself ever
wasting time restoring them. As soon as i cleared the decks of this crap
and a trailer load of other un-mentionables some dude rings and says he
has a whole other pile of stuff he wants to donate to a good home.
So one lot of junk got replaced with another bigger lot, and including 4
more CROs, one of which is tubed, and runs far too hot so it is only for
emergencies tendered with reluctance.

Patrick Turner.- Hide quoted text -

- Show quoted text -

LOL, funnily enough this stuff is quite collectable. Mainly by people
who collect TEK or HP kit to laugh at. Seriously though you can learn
a hell of a lot rebuilding old scopes and test gear,it tends to be
built to be repaired. The old Cossor stuff is nice, built like a tank
check out this site, he may be able to help: http://www.thevalvepage.com/testeq/scope.htm

I do get a bit niggly when people rip a going concern to bits just to
use the trannys, tagstrips, sockets etc. They end up with a whole pile
of ****e and have learnt nothing in the process of destruction. Better
to repair it and realise its crap than make something that took up
3cuft of space into some great pile that really becomes a problem.
Matt

The 1045K was the scope of last resort even when I was an apprentice in
the late '50s, it was heavy, inaccurate, had no bandwidth, and was not
particularly reliable. It was a revalation to get to use a Tek 545 the
first scope that I ever used that triggered reliably every time and was
accurate enough to take measurements off the screen.

I've got an old Tek 475A that I bought off ebay. It is probably the best
all round analog scope ever. Almost makes me nostalgic for the old days
of a broken mainframe, a pile of logic manuals, a pot of coffee, a pack
of cigarettes, and nowhere to go for the rest of the night.

Keith

[bigwig]

On 15 Apr, 14:06, keithr wrote:
bigwig wrote:
On 14 Apr, 15:22, Patrick Turner wrote:
keithr wrote:

Mark wrote:
I'm trying to repair a Cossor 1045K Oscilloscope and would be grateful
if anyone could point me in the direction of the service / operator
manual. I can find a copy of the circuit diagram fromwww.mauritron.com,
but ideally I would like to get a copy of the full manual.
The CRT appears to be working fine as the X and Y position adjustments
work. When I connect the Y input to the built in 1V pk-pk AC test
signal the scope displays a vertical line, but the test signal itself
appears to be ok. Changing the timebase makes no difference to the
display and the output from TB OUTPUT is a constant 187V DC. The end
of a wire that is connected to the timebase switch has come loose, but
it is not clear to where the other end should be connected. If anyone
has a working example I would appreciate if they could tell me to
where this wire should be connected, it is the short black wire from
the bottom of the rotary timebase switch (the pin that also has a wire
to the 2 uF capacitor that is mounted on the switch and another red
wire connected).
Thanks,
Mark
Why on earth would you want to fix one of those things. They were a
crappy scope even in their heyday, you can do much better for a very
moderate price these days.
Keith
I chucked out a couple of veteran CROs recently yo stop myself ever
wasting time restoring them. As soon as i cleared the decks of this crap
and a trailer load of other un-mentionables some dude rings and says he
has a whole other pile of stuff he wants to donate to a good home.
So one lot of junk got replaced with another bigger lot, and including 4
more CROs, one of which is tubed, and runs far too hot so it is only for
emergencies tendered with reluctance.

Patrick Turner.- Hide quoted text -

- Show quoted text -

LOL, funnily enough this stuff is quite collectable. Mainly by people
who collect TEK or HP kit to laugh at. Seriously though you can learn
a hell of a lot rebuilding old scopes and test gear,it tends to be
built to be repaired. The old Cossor stuff is nice, built like a tank
check out this site, he may be able to help: *http://www.thevalvepage..com/testeq/scope.htm

I do get a bit niggly when people rip a going concern to bits just to
use the trannys, tagstrips, sockets etc. They end up with a whole pile
of ****e and have learnt nothing in the process of destruction. Better
to repair it and realise its crap than make something that took up
3cuft of space into some great pile that really becomes a problem.
* Matt

The 1045K was the scope of last resort even when I was an apprentice in
the late '50s, it was heavy, inaccurate, had no bandwidth, and was not
particularly reliable. It was a revalation to get to use a Tek 545 the
first scope that I ever used that triggered reliably every time and was
accurate enough to take measurements off the screen.

I've got an old Tek 475A that I bought off ebay. It is probably the best
all round analog scope ever. Almost makes me nostalgic for the old days
of a broken mainframe, a pile of logic manuals, a pot of coffee, a pack
of cigarettes, and nowhere to go for the rest of the night.

Keith- Hide quoted text -

- Show quoted text -

I lost the bidding on a 547 last week ;-( what I would really like is
a 570 (rare) or a 575 curve tracer. Trouble is they still demand a
high price. Anyone got a decent schematic of a scope add on to do it.
I have an old Kenwood heap of crap that needs a use.
The Tek trigger is legendary. Years ago I found a home built valve
scope in a skip. I sorted it out and it was quite good out to about
1Mhz and the trigger was a delight. It was a very advanced scope for a
home build or even for the period, the caps were all datecoded 1943.
Mind you it could have been built later but I think it was somewhere
around that period because all the valves apart from a small diode,
rectifiers and a series pass tube were either the red painted jobs or
metal. The chassis was a sight to behold it was of aircraft quality,
all ally, lovely rivets and rivnuts. It could have been a prototype or
someone who really knew what they were doing. Oddly the input sockets
were the UK standard TV aerial jobbys. My father got rid of it when I
left home and has never admitted it. Wonder where it is now, probably
landfill.
Matt.

[Dr. Barry L. Ornitz]

"bigwig" wrote in message news:5e9a5bc8-
...
I lost the bidding on a 547 last week ;-( what I would really like
is a 570 (rare) or a 575 curve tracer. Trouble is they still
demand a high price. Anyone got a decent schematic of a scope add
on to do it. I have an old Kenwood heap of crap that needs a use.

Lots of curve tracer circuits can be found, but few are worth the cost of
components.

The Tektronix 7CT1 curve tracer plug-in is usually available at moderate
prices. While primarily a BJT and FET testing device, it can be adapted
for testing many vacuum tubes. The 570 is now unobtanium but an
occasional 576 can be found. The 7CT1 works with the 7000 series of
oscilloscope mainframes.

The Tek 547 is prone to high voltage transformer failures, but the 543B,
544, 545B, 546, and 547 all use the same HV transformer so finding a
replacement is not difficult. Everyone interested in older Tektronix
oscilloscopes should get a copy of "Oscilloscopes:
Selecting and Restoring a Classic" by Stan Griffiths - W7NI. You might
wish to visit his website too as it is full of valuable information:
http://www.reprise.com/ash/clients2/.

I have a 585A and a militarized 7603, but my interests lie with RF, not
audio. I also have a large collection of plug-ins for both scopes.
Hollow-state enthusiasts should love the 585A as it is an excellent space
heater drawing close to a kilowatt. The 585A is still my favorite bench
scope when used with a four-trace 1A4 plug-in. The solid-state 7603 is
considerably more portable though!

The 453, 455, 465, and 475 are all good portable scopes too. Any newer
Tek scope, like the 2213, uses specialized parts and are essentially
non-repairable. Even Tektronix learned this the hard way. The vacuum
tube and discrete semiconductor scopes all use readily available parts
(even the tunnel diodes used in the sweep circuits are still available).

If you should email Stan Griffiths, I suggest you refrain from bragging
about being a golden-eared glass-audiophool. Stan never forgave the
wholesale slaughter of many good scopes by people only wanting to scavenge
6DJ8's.

73, Dr. Barry L. Ornitz WA4VZQ

[KeithR]

bigwig wrote:
On 15 Apr, 14:06, keithr wrote:
bigwig wrote:
On 14 Apr, 15:22, Patrick Turner wrote:
keithr wrote:
Mark wrote:
I'm trying to repair a Cossor 1045K Oscilloscope and would be grateful
if anyone could point me in the direction of the service / operator
manual. I can find a copy of the circuit diagram fromwww.mauritron.com,
but ideally I would like to get a copy of the full manual.
The CRT appears to be working fine as the X and Y position adjustments
work. When I connect the Y input to the built in 1V pk-pk AC test
signal the scope displays a vertical line, but the test signal itself
appears to be ok. Changing the timebase makes no difference to the
display and the output from TB OUTPUT is a constant 187V DC. The end
of a wire that is connected to the timebase switch has come loose, but
it is not clear to where the other end should be connected. If anyone
has a working example I would appreciate if they could tell me to
where this wire should be connected, it is the short black wire from
the bottom of the rotary timebase switch (the pin that also has a wire
to the 2 uF capacitor that is mounted on the switch and another red
wire connected).
Thanks,
Mark
Why on earth would you want to fix one of those things. They were a
crappy scope even in their heyday, you can do much better for a very
moderate price these days.
Keith
I chucked out a couple of veteran CROs recently yo stop myself ever
wasting time restoring them. As soon as i cleared the decks of this crap
and a trailer load of other un-mentionables some dude rings and says he
has a whole other pile of stuff he wants to donate to a good home.
So one lot of junk got replaced with another bigger lot, and including 4
more CROs, one of which is tubed, and runs far too hot so it is only for
emergencies tendered with reluctance.
Patrick Turner.- Hide quoted text -
- Show quoted text -
LOL, funnily enough this stuff is quite collectable. Mainly by people
who collect TEK or HP kit to laugh at. Seriously though you can learn
a hell of a lot rebuilding old scopes and test gear,it tends to be
built to be repaired. The old Cossor stuff is nice, built like a tank
check out this site, he may be able to help: http://www.thevalvepage.com/testeq/scope.htm
I do get a bit niggly when people rip a going concern to bits just to
use the trannys, tagstrips, sockets etc. They end up with a whole pile
of ****e and have learnt nothing in the process of destruction. Better
to repair it and realise its crap than make something that took up
3cuft of space into some great pile that really becomes a problem.
Matt
The 1045K was the scope of last resort even when I was an apprentice in
the late '50s, it was heavy, inaccurate, had no bandwidth, and was not
particularly reliable. It was a revalation to get to use a Tek 545 the
first scope that I ever used that triggered reliably every time and was
accurate enough to take measurements off the screen.

I've got an old Tek 475A that I bought off ebay. It is probably the best
all round analog scope ever. Almost makes me nostalgic for the old days
of a broken mainframe, a pile of logic manuals, a pot of coffee, a pack
of cigarettes, and nowhere to go for the rest of the night.

Keith- Hide quoted text -

- Show quoted text -

I lost the bidding on a 547 last week ;-( what I would really like is
a 570 (rare) or a 575 curve tracer. Trouble is they still demand a
high price. Anyone got a decent schematic of a scope add on to do it.
I have an old Kenwood heap of crap that needs a use.
The Tek trigger is legendary. Years ago I found a home built valve
scope in a skip. I sorted it out and it was quite good out to about
1Mhz and the trigger was a delight. It was a very advanced scope for a
home build or even for the period, the caps were all datecoded 1943.
Mind you it could have been built later but I think it was somewhere
around that period because all the valves apart from a small diode,
rectifiers and a series pass tube were either the red painted jobs or
metal. The chassis was a sight to behold it was of aircraft quality,
all ally, lovely rivets and rivnuts. It could have been a prototype or
someone who really knew what they were doing. Oddly the input sockets
were the UK standard TV aerial jobbys. My father got rid of it when I
left home and has never admitted it. Wonder where it is now, probably
landfill.
Matt.

Yep the bigger Teks that had plug in modules were amazingly versatile.
My favourite plugins were the time domain reflectometer for checking
long runs of RF cable and the logic analyser an essential looking for
bugs in complex digital circuits.

That other scope sounds almost like the ones that we had to make as an
apprentice exercise. It had a small crt and was all tube other than the
HT rectifier. There was a heavy emphasis on good chassis work. I can't
remember whether it had Belling Lee connectors or not, but I suspect
that it would have.

[bigwig]

On 16 Apr, 12:54, keithr wrote:
bigwig wrote:
On 15 Apr, 14:06, keithr wrote:
bigwig wrote:
On 14 Apr, 15:22, Patrick Turner wrote:
keithr wrote:
Mark wrote:
I'm trying to repair a Cossor 1045K Oscilloscope and would be grateful
if anyone could point me in the direction of the service / operator
manual. I can find a copy of the circuit diagram fromwww.mauritron..com,
but ideally I would like to get a copy of the full manual.
The CRT appears to be working fine as the X and Y position adjustments
work. When I connect the Y input to the built in 1V pk-pk AC test
signal the scope displays a vertical line, but the test signal itself
appears to be ok. Changing the timebase makes no difference to the
display and the output from TB OUTPUT is a constant 187V DC. The end
of a wire that is connected to the timebase switch has come loose, but
it is not clear to where the other end should be connected. If anyone
has a working example I would appreciate if they could tell me to
where this wire should be connected, it is the short black wire from
the bottom of the rotary timebase switch (the pin that also has a wire
to the 2 uF capacitor that is mounted on the switch and another red
wire connected).
Thanks,
Mark
Why on earth would you want to fix one of those things. They were a
crappy scope even in their heyday, you can do much better for a very
moderate price these days.
Keith
I chucked out a couple of veteran CROs recently yo stop myself ever
wasting time restoring them. As soon as i cleared the decks of this crap
and a trailer load of other un-mentionables some dude rings and says he
has a whole other pile of stuff he wants to donate to a good home.
So one lot of junk got replaced with another bigger lot, and including 4
more CROs, one of which is tubed, and runs far too hot so it is only for
emergencies tendered with reluctance.
Patrick Turner.- Hide quoted text -
- Show quoted text -
LOL, funnily enough this stuff is quite collectable. Mainly by people
who collect TEK or HP kit to laugh at. Seriously though you can learn
a hell of a lot rebuilding old scopes and test gear,it tends to be
built to be repaired. The old Cossor stuff is nice, built like a tank
check out this site, he may be able to help: *http://www.thevalvepage.com/testeq/scope.htm
I do get a bit niggly when people rip a going concern to bits just to
use the trannys, tagstrips, sockets etc. They end up with a whole pile
of ****e and have learnt nothing in the process of destruction. Better
to repair it and realise its crap than make something that took up
3cuft of space into some great pile that really becomes a problem.
* Matt
The 1045K was the scope of last resort even when I was an apprentice in
the late '50s, it was heavy, inaccurate, had no bandwidth, and was not
particularly reliable. It was a revalation to get to use a Tek 545 the
first scope that I ever used that triggered reliably every time and was
accurate enough to take measurements off the screen.

I've got an old Tek 475A that I bought off ebay. It is probably the best
all round analog scope ever. Almost makes me nostalgic for the old days
of a broken mainframe, a pile of logic manuals, a pot of coffee, a pack
of cigarettes, and nowhere to go for the rest of the night.

Keith- Hide quoted text -

- Show quoted text -

I lost the bidding on a 547 last week ;-( what I would really like is
a 570 (rare) or a 575 curve tracer. Trouble is they still demand a
high price. Anyone got a decent schematic of a scope add on to do it.
I have an old Kenwood heap of crap that needs a use.
*The Tek trigger is legendary. Years ago I found a home built valve
scope in a skip. I sorted it out and it was quite good out to about
1Mhz and the trigger was a delight. It was a very advanced scope for a
home build or even for the period, the caps were all datecoded 1943.
Mind you it could have been built later but I think it was somewhere
around that period because all the valves apart from a small diode,
rectifiers and a series pass tube were either the red painted jobs or
metal. The chassis was a sight to behold it was of aircraft quality,
all ally, lovely rivets and rivnuts. It could have been a prototype or
someone who really knew what they were doing. Oddly the input sockets
were the UK standard TV aerial jobbys. My father got rid of it when I
left home and has never admitted it. Wonder where it is now, probably
landfill.
* Matt.

Yep the bigger Teks that had plug in modules were amazingly versatile.
My favourite plugins were the time domain reflectometer for checking
long runs of RF cable and the logic analyser an essential looking for
bugs in complex digital circuits.

That other scope sounds almost like the ones that we had to make as an
apprentice exercise. It had a small crt and was all tube other than the
HT rectifier. There was a heavy emphasis on good chassis work. I can't
remember whether it had Belling Lee connectors or not, but I suspect
that it would have.- Hide quoted text -

- Show quoted text -

I thought it could have been an apprentice piece, really was nice. I
guess it could have been later than 43 then. Did you get the chance to
buy yours after you finished or was it recycled for the next chaps?
The CRT was 3 inch IIRC and it had one of those tiddly little diode
valves under the chassis.
Cheers Matt

[bigwig]

On 16 Apr, 02:45, "Dr. Barry L. Ornitz"
wrote:
"bigwig" wrote in message news:5e9a5bc8-

...

I lost the bidding on a 547 last week ;-( what I would really like
is a 570 (rare) or a 575 curve tracer. Trouble is they still
demand a high price. Anyone got a decent schematic of a scope add
on to do it. I have an old Kenwood heap of crap that needs a use.

Lots of curve tracer circuits can be found, but few are worth the cost of
components.

The Tektronix 7CT1 curve tracer plug-in is usually available at moderate
prices. *While primarily a BJT and FET testing device, it can be adapted
for testing many vacuum tubes. *The 570 is now unobtanium but an
occasional 576 can be found. *The 7CT1 works with the 7000 series of
oscilloscope mainframes.

The Tek 547 is prone to high voltage transformer failures, but the 543B,
544, 545B, 546, and 547 all use the same HV transformer so finding a
replacement is not difficult. *Everyone interested in older Tektronix
oscilloscopes should get a copy of "Oscilloscopes:
Selecting and Restoring a Classic" by Stan Griffiths - W7NI. *You might
wish to visit his website too as it is full of valuable information:http://www.reprise.com/ash/clients2/.

I have a 585A and a militarized 7603, but my interests lie with RF, not
audio. *I also have a large collection of plug-ins for both scopes.
Hollow-state enthusiasts should love the 585A as it is an excellent space
heater drawing close to a kilowatt. *The 585A is still my favorite bench
scope when used with a four-trace 1A4 plug-in. *The solid-state 7603 is
considerably more portable though!

The 453, 455, 465, and 475 are all good portable scopes too. *Any newer
Tek scope, like the 2213, uses specialized parts and are essentially
non-repairable. *Even Tektronix learned this the hard way. *The vacuum
tube and discrete semiconductor scopes all use readily available parts
(even the tunnel diodes used in the sweep circuits are still available).

If you should email Stan Griffiths, I suggest you refrain from bragging
about being a golden-eared glass-audiophool. *Stan never forgave the
wholesale slaughter of many good scopes by people only wanting to scavenge
6DJ8's.

* * 73, Dr. Barry L. Ornitz *WA4VZQ

A friend just aquired a 465 with the DMM on the top. It was dead and
we found it was the tripler. I dug it out and built up some new guts,
now works a treat.
I have a 2235 and I dont agree that the 22 series have Tek specific
parts, although the 2213 may be one of the horrible plastic handled
jobs that just about pass as Tek. I think they may have outsourced on
this lower end stuff. My 2235 is a delight to use and when I repaired
it I had no trouble, the same cannot be said for the 465. It is a
wonderfull design, but a real pain to work on, note I did not say with
as it is a lovely scope in the usual Tek tradition. Considering he got
it for nothing and the diodes and caps for the new tripler cost about
five quid he got real bargain.
Since I got my scope I have caught the Tek bug and would love to get
a 7000 series frame, they do seem to be the ultimate in flexibility. I
see your point on portability, the 2235 is as light as a feather but
the 465 is a beast although roughly the same on paper I think the 465
has the edge. I have never seen a 2230 digital/analogue scope but they
look nice for a portable. Of course there is the tiny wee 212 or at
the other extreme and something else I would love a 555.
Cheers Matt.

[Dr. Barry L. Ornitz]

"bigwig" wrote in message news:684911e8-
...
A friend just acquired a 465 with the DMM on the top. It was
dead and we found it was the tripler. I dug it out and built up
some new guts, now works a treat.

This is a relatively common failure mode. Sadly the HV diodes are not
supplied by Digi-Key or Mouser, but Newark and Allied carry them. Often
TV triplers can be used. On your side of the pond, perhaps Farnell might
carry what you need.

I have a 2235 and I don't agree that the 22 series have Tek
specific parts, although the 2213 may be one of the horrible
plastic handled jobs that just about pass as Tek. I think
they may have outsourced on this lower end stuff.

If I remember correctly, in a conversation with three friends who were
engineers at Tek, I was told that this series was manufactured jointly
with Sony, and most do use Tek or Sony specific IC's. In fact Tek lost
money on many of these models because of differences in parts between
different production runs. Even Tek could not repair them!

My 2235 is a delight to use and when I repaired it I had no
trouble, the same cannot be said for the 465. It is a wonderful
design, but a real pain to work on, note I did not say with
as it is a lovely scope in the usual Tek tradition. Considering
he got it for nothing and the diodes and caps for the new tripler
cost about five quid he got real bargain.

Stan Griffiths notes that the year 1969 is the dividing year between
easily repairable scopes and those that may be impossible to repair -
because often the only source for the custom IC's and microprocessors is
another scrapped instrument. This is the year that the 7000 and TM500
series of scopes were introduced. According to Stan, "I expect the
average Tek scope made in the 60s to outlive most of those made in the
70s or 80s if they are properly cared for."

Since I got my scope I have caught the Tek bug and would love to
get a 7000 series frame, they do seem to be the ultimate in
flexibility. I see your point on portability, the 2235 is as
light as a feather but the 465 is a beast although roughly the
same on paper I think the 465 has the edge. I have never seen a
2230 digital/analogue scope but they look nice for a portable.
Of course there is the tiny wee 212 or at the other extreme and
something else I would love a 555.

For the bench, a 500 series scope cannot be beat. I would not part with
my 585. This is a 100 MHz scope, but unlike other 100 MHz scopes, its
response rolls off gradually to well above 400 MHz. The trigger circuits
work to above 400 MHz too. I routinely troubleshoot circuits at 450 MHz
with mine, and if I need to go higher, I have the 1S1 DC to 1 GHz
sampling plug-in. A 100 MHz scope of today has a response that drops to
near zero just a little above 100 MHz. If you run across a scope cart,
immediately buy it. Also keep the fans and filters clean.

If you do significant digital troubleshooting, the 7000 series might be a
better choice. Before you purchase any 22xx scope, look inside for
specialized integrated circuits. You might save yourself lots of grief.

73, Dr. Barry L. Ornitz WA4VZQ

[KeithR]

bigwig wrote:
On 16 Apr, 12:54, keithr wrote:
bigwig wrote:
On 15 Apr, 14:06, keithr wrote:
bigwig wrote:
On 14 Apr, 15:22, Patrick Turner wrote:
keithr wrote:
Mark wrote:
I'm trying to repair a Cossor 1045K Oscilloscope and would be grateful
if anyone could point me in the direction of the service / operator
manual. I can find a copy of the circuit diagram fromwww.mauritron.com,
but ideally I would like to get a copy of the full manual.
The CRT appears to be working fine as the X and Y position adjustments
work. When I connect the Y input to the built in 1V pk-pk AC test
signal the scope displays a vertical line, but the test signal itself
appears to be ok. Changing the timebase makes no difference to the
display and the output from TB OUTPUT is a constant 187V DC. The end
of a wire that is connected to the timebase switch has come loose, but
it is not clear to where the other end should be connected. If anyone
has a working example I would appreciate if they could tell me to
where this wire should be connected, it is the short black wire from
the bottom of the rotary timebase switch (the pin that also has a wire
to the 2 uF capacitor that is mounted on the switch and another red
wire connected).
Thanks,
Mark
Why on earth would you want to fix one of those things. They were a
crappy scope even in their heyday, you can do much better for a very
moderate price these days.
Keith
I chucked out a couple of veteran CROs recently yo stop myself ever
wasting time restoring them. As soon as i cleared the decks of this crap
and a trailer load of other un-mentionables some dude rings and says he
has a whole other pile of stuff he wants to donate to a good home.
So one lot of junk got replaced with another bigger lot, and including 4
more CROs, one of which is tubed, and runs far too hot so it is only for
emergencies tendered with reluctance.
Patrick Turner.- Hide quoted text -
- Show quoted text -
LOL, funnily enough this stuff is quite collectable. Mainly by people
who collect TEK or HP kit to laugh at. Seriously though you can learn
a hell of a lot rebuilding old scopes and test gear,it tends to be
built to be repaired. The old Cossor stuff is nice, built like a tank
check out this site, he may be able to help: http://www.thevalvepage.com/testeq/scope.htm
I do get a bit niggly when people rip a going concern to bits just to
use the trannys, tagstrips, sockets etc. They end up with a whole pile
of ****e and have learnt nothing in the process of destruction. Better
to repair it and realise its crap than make something that took up
3cuft of space into some great pile that really becomes a problem.
Matt
The 1045K was the scope of last resort even when I was an apprentice in
the late '50s, it was heavy, inaccurate, had no bandwidth, and was not
particularly reliable. It was a revalation to get to use a Tek 545 the
first scope that I ever used that triggered reliably every time and was
accurate enough to take measurements off the screen.
I've got an old Tek 475A that I bought off ebay. It is probably the best
all round analog scope ever. Almost makes me nostalgic for the old days
of a broken mainframe, a pile of logic manuals, a pot of coffee, a pack
of cigarettes, and nowhere to go for the rest of the night.
Keith- Hide quoted text -
- Show quoted text -
I lost the bidding on a 547 last week ;-( what I would really like is
a 570 (rare) or a 575 curve tracer. Trouble is they still demand a
high price. Anyone got a decent schematic of a scope add on to do it.
I have an old Kenwood heap of crap that needs a use.
The Tek trigger is legendary. Years ago I found a home built valve
scope in a skip. I sorted it out and it was quite good out to about
1Mhz and the trigger was a delight. It was a very advanced scope for a
home build or even for the period, the caps were all datecoded 1943.
Mind you it could have been built later but I think it was somewhere
around that period because all the valves apart from a small diode,
rectifiers and a series pass tube were either the red painted jobs or
metal. The chassis was a sight to behold it was of aircraft quality,
all ally, lovely rivets and rivnuts. It could have been a prototype or
someone who really knew what they were doing. Oddly the input sockets
were the UK standard TV aerial jobbys. My father got rid of it when I
left home and has never admitted it. Wonder where it is now, probably
landfill.
Matt.
Yep the bigger Teks that had plug in modules were amazingly versatile.
My favourite plugins were the time domain reflectometer for checking
long runs of RF cable and the logic analyser an essential looking for
bugs in complex digital circuits.

That other scope sounds almost like the ones that we had to make as an
apprentice exercise. It had a small crt and was all tube other than the
HT rectifier. There was a heavy emphasis on good chassis work. I can't
remember whether it had Belling Lee connectors or not, but I suspect
that it would have.- Hide quoted text -

- Show quoted text -

I thought it could have been an apprentice piece, really was nice. I
guess it could have been later than 43 then. Did you get the chance to
buy yours after you finished or was it recycled for the next chaps?
The CRT was 3 inch IIRC and it had one of those tiddly little diode
valves under the chassis.
Cheers Matt

The tube size sounds about right, from what I remember, there was a
bulkhead about 2/3rds of the way back that had the tube base mounted on
it with the power supply behind that. The front panel was gray, and the
chassis consisted of the front panel, the mid bulkhead and the back
panel wich were joined by thin aluminium moldings at each corner. The
cover slipped on from the back. The early ones had a u-metal shield
around the tube, later ones just had a tin one. A favourite joke was to
slip a magnet inside the shield while the unfortunate victim was
distracted, and then watch him go mad trying to find what had happened
to his trace. These scopes were made to be sold to other tech colleges,
so we never got to keep them. In fact we never got to keep any of the
electronic exercises, only the tools that we made in the first year
mechanical shop.

Keith

[bigwig]

On 20 Apr, 02:13, keithr wrote:
bigwig wrote:
On 16 Apr, 12:54, keithr wrote:
bigwig wrote:
On 15 Apr, 14:06, keithr wrote:
bigwig wrote:
On 14 Apr, 15:22, Patrick Turner wrote:
keithr wrote:
Mark wrote:
I'm trying to repair a Cossor 1045K Oscilloscope and would be grateful
if anyone could point me in the direction of the service / operator
manual. I can find a copy of the circuit diagram fromwww.mauritron.com,
but ideally I would like to get a copy of the full manual.
The CRT appears to be working fine as the X and Y position adjustments
work. When I connect the Y input to the built in 1V pk-pk AC test
signal the scope displays a vertical line, but the test signal itself
appears to be ok. Changing the timebase makes no difference to the
display and the output from TB OUTPUT is a constant 187V DC. The end
of a wire that is connected to the timebase switch has come loose, but
it is not clear to where the other end should be connected. If anyone
has a working example I would appreciate if they could tell me to
where this wire should be connected, it is the short black wire from
the bottom of the rotary timebase switch (the pin that also has a wire
to the 2 uF capacitor that is mounted on the switch and another red
wire connected).
Thanks,
Mark
Why on earth would you want to fix one of those things. They were a
crappy scope even in their heyday, you can do much better for a very
moderate price these days.
Keith
I chucked out a couple of veteran CROs recently yo stop myself ever
wasting time restoring them. As soon as i cleared the decks of this crap
and a trailer load of other un-mentionables some dude rings and says he
has a whole other pile of stuff he wants to donate to a good home.
So one lot of junk got replaced with another bigger lot, and including 4
more CROs, one of which is tubed, and runs far too hot so it is only for
emergencies tendered with reluctance.
Patrick Turner.- Hide quoted text -
- Show quoted text -
LOL, funnily enough this stuff is quite collectable. Mainly by people
who collect TEK or HP kit to laugh at. Seriously though you can learn
a hell of a lot rebuilding old scopes and test gear,it tends to be
built to be repaired. The old Cossor stuff is nice, built like a tank
check out this site, he may be able to help: *http://www.thevalvepage.com/testeq/scope.htm
I do get a bit niggly when people rip a going concern to bits just to
use the trannys, tagstrips, sockets etc. They end up with a whole pile
of ****e and have learnt nothing in the process of destruction. Better
to repair it and realise its crap than make something that took up
3cuft of space into some great pile that really becomes a problem.
* Matt
The 1045K was the scope of last resort even when I was an apprentice in
the late '50s, it was heavy, inaccurate, had no bandwidth, and was not
particularly reliable. It was a revalation to get to use a Tek 545 the
first scope that I ever used that triggered reliably every time and was
accurate enough to take measurements off the screen.
I've got an old Tek 475A that I bought off ebay. It is probably the best
all round analog scope ever. Almost makes me nostalgic for the old days
of a broken mainframe, a pile of logic manuals, a pot of coffee, a pack
of cigarettes, and nowhere to go for the rest of the night.
Keith- Hide quoted text -
- Show quoted text -
I lost the bidding on a 547 last week ;-( what I would really like is
a 570 (rare) or a 575 curve tracer. Trouble is they still demand a
high price. Anyone got a decent schematic of a scope add on to do it.
I have an old Kenwood heap of crap that needs a use.
*The Tek trigger is legendary. Years ago I found a home built valve
scope in a skip. I sorted it out and it was quite good out to about
1Mhz and the trigger was a delight. It was a very advanced scope for a
home build or even for the period, the caps were all datecoded 1943.
Mind you it could have been built later but I think it was somewhere
around that period because all the valves apart from a small diode,
rectifiers and a series pass tube were either the red painted jobs or
metal. The chassis was a sight to behold it was of aircraft quality,
all ally, lovely rivets and rivnuts. It could have been a prototype or
someone who really knew what they were doing. Oddly the input sockets
were the UK standard TV aerial jobbys. My father got rid of it when I
left home and has never admitted it. Wonder where it is now, probably
landfill.
* Matt.
Yep the bigger Teks that had plug in modules were amazingly versatile.
My favourite plugins were the time domain reflectometer for checking
long runs of RF cable and the logic analyser an essential looking for
bugs in complex digital circuits.

That other scope sounds almost like the ones that we had to make as an
apprentice exercise. It had a small crt and was all tube other than the
HT rectifier. There was a heavy emphasis on good chassis work. I can't
remember whether it had Belling Lee connectors or not, but I suspect
that it would have.- Hide quoted text -

- Show quoted text -

I thought it could have been an apprentice piece, really was nice. I
guess it could have been later than 43 then. Did you get the chance to
buy yours after you finished or was it recycled for the next chaps?
The CRT was 3 inch IIRC and it had one of those tiddly little diode
valves under the chassis.
* Cheers Matt

The tube size sounds about right, from what I remember, there was a
bulkhead about 2/3rds of the way back that had the tube base mounted on
it with the power supply behind that. The front panel was gray, and the
chassis consisted of the front panel, the mid bulkhead and the back
panel wich were joined by thin aluminium moldings at each corner. The
cover slipped on from the back. The early ones had a u-metal shield
around the tube, later ones just had a tin one. A favourite joke was to
slip a magnet inside the shield while the unfortunate victim was
distracted, and then watch him go mad trying to find what had happened
to his trace. These scopes were made to be sold to other tech colleges,
so we never got to keep them. In fact we never got to keep any of the
electronic exercises, only the tools that we made in the first year
mechanical shop.

Keith- Hide quoted text -

- Show quoted text -

Yes that sounds exactly like the one I had. All the front panel
markings were typed on sticky labels. Shame it went really. The only
fault apart from sketchy rubber insulation on several wires (just
didnt move them much) was one cap in the timebase. I replaced it with
an ugly radial modern thing. If I still had it I would probably do a
respectful rebuild because it was really quite nice for the period or
periods, because I guess they got recycled for the next lot of
students. To be honest it was really good when you consider where I
found it in a skip at the back of what was then the local saw mill. It
was probably in there for a couple of months and it was really raining
like some biblical scene. I held the thing in one hand as I rode home
on my clapped out old racer with the handle bars upside down and no
brakes. My mate Kingsford a man mountain even back then refused to
help in any way. Ah nostalgia.
Its a shame you guys didnt get to keep any of your electronic stuff
I did my appreniceship with what was then an aircraft instrument
company based near Cheltenham, we got to keep our mechanical stuff.
You know the sort of thing, centre punch, tap handle and useless piece
of plate they made you chissel out ten mill squares on. I also never
got to keep the sliver of six inch bar they made me cut through for
leaving the chuck key in the chuck;-). I built a voltage and current
regulated bench supply of my own design and they allowed me to keep
this. Mind you so they should I provided my own transformer and all
the power transistors. We didnt get to do anything as interesting as
build a scope. All we did in this respect was study theory with a half
interested tutor. I think they should really try and re-vitalise
apprenticeships and give some kids a chance in life.
Cheers Matt.