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Jesse Skeens
 
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Default ADA Stereo Delay repair advice needed

I have the STD-1 with a problem. When I turn it on the lights come on
and then about 10-15 seconds later the lights fade out. At that point
the input light just flashes about 120 times a minute (yes I counted).

I tried replacing the main two caps right after the powersupply but no
luck.

Any idea on what this could be and if not does anyone know of a place
that would specialize in this kind of thing? I already emailed
Analogman and am awaiting response.

Thanks

Jesse
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Scott Dorsey
 
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Jesse Skeens wrote:
I have the STD-1 with a problem. When I turn it on the lights come on
and then about 10-15 seconds later the lights fade out. At that point
the input light just flashes about 120 times a minute (yes I counted).

I tried replacing the main two caps right after the powersupply but no
luck.


More likely it's one of the smaller decoupling caps. One of the tantalums
is failing into a short when it heats up. You can try using freezone on
them individually and seeing which one cures it. If you are VERY careful
you can start cold and individually heat the tantalums up with a soldering
iron until you find the guilty one. Or you can shotgun all of them.

Could also be a cold solder joint, but if it's thermally related, the
tantalums are a very popular failure.

If you have any chips that are in sockets, pull them out and reseat them
too. That's another source of thermal issues, although a less popular one.

Any idea on what this could be and if not does anyone know of a place
that would specialize in this kind of thing? I already emailed
Analogman and am awaiting response.


This stuff is easy to work on. Your neighborhood TV repair can deal with
it.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."
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Jesse Skeens
 
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More likely it's one of the smaller decoupling caps. One of the tantalums
is failing into a short when it heats up. You can try using freezone on
them individually and seeing which one cures it. If you are VERY careful
you can start cold and individually heat the tantalums up with a soldering
iron until you find the guilty one. Or you can shotgun all of them.



Scott,

I looked up Freezone but didn't find anything, is that the correct
spelling? I assume this is some kind of freon I can spray on the cap
to keep it cool?

As far as taking it to a TV repair place do they need schematics
or anything special like that?

Jesse
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Scott Dorsey
 
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Jesse Skeens wrote:
More likely it's one of the smaller decoupling caps. One of the tantalums
is failing into a short when it heats up. You can try using freezone on
them individually and seeing which one cures it. If you are VERY careful
you can start cold and individually heat the tantalums up with a soldering
iron until you find the guilty one. Or you can shotgun all of them.


I looked up Freezone but didn't find anything, is that the correct
spelling? I assume this is some kind of freon I can spray on the cap
to keep it cool?


It's a kind of spray that cools things down _abnormally_ so that you can
find things that fail when they freeze or get hot. I don't know if
Freezone brand is still around, but I am sure GC Electronics sells something
like it, and your local electronics parts place probably carries it.

As far as taking it to a TV repair place do they need schematics
or anything special like that?


It would probably help, but the fact that it's temperature related and it's
on the digital side might be enough. If you're paying time and materials
for work, you will invariably wind up paying less if you provide complete
documentation, though.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."
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Eric K. Weber
 
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Look at www.newark.com enter freeze in the search box.... to see what
Scott had in mind....

However the first thing you should do is look for the ....warmest
component... other than the pass transistor or regulator in the power
supply..... Although tantalums are one suspect, they are not the only
one..... cmos logic chips are another suspect....

If you have a board layout you can use a milivolt meter to find the
problem.... measure the voltage drop in a couple of inches of circuit board
trace on the power supply distribution lines (an ammeter with the resistance
of the circuit board trace as the shunt).... when you get to the place in
the distribution line with no drop you have passed the shorted point.

Regards:
Eric

"Jesse Skeens" wrote in message
om...
More likely it's one of the smaller decoupling caps. One of the

tantalums
is failing into a short when it heats up. You can try using freezone on
them individually and seeing which one cures it. If you are VERY

careful
you can start cold and individually heat the tantalums up with a

soldering
iron until you find the guilty one. Or you can shotgun all of them.



Scott,

I looked up Freezone but didn't find anything, is that the correct
spelling? I assume this is some kind of freon I can spray on the cap
to keep it cool?

As far as taking it to a TV repair place do they need schematics
or anything special like that?

Jesse





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ThePaulThomas
 
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(Jesse Skeens) wrote in message . com...
I looked up Freezone but didn't find anything, is that the correct
spelling? I assume this is some kind of freon I can spray on the cap
to keep it cool?

As far as taking it to a TV repair place do they need schematics
or anything special like that?

Jesse


All the documentation and schematics for the STD-1 can be found he

http://www.adadepot.com/adagear/gear.../ADA-STD-1.htm

Those are definitely cool sounding units. A lot of fun to play around
with. And apparently they're somewhat rare because I've seen more than
one of them sell for over $400 on eBay within the past couple of
years. Do you have the version with 1/4" inputs/outputs, or is yours
XLR? I think the XLR ("studio") version is the _very_ rare one.
  #7   Report Post  
Jesse Skeens
 
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(ThePaulThomas) wrote in message . com...
(Jesse Skeens) wrote in message . com...
I looked up Freezone but didn't find anything, is that the correct
spelling? I assume this is some kind of freon I can spray on the cap
to keep it cool?

As far as taking it to a TV repair place do they need schematics
or anything special like that?

Jesse


All the documentation and schematics for the STD-1 can be found he

http://www.adadepot.com/adagear/gear.../ADA-STD-1.htm

Those are definitely cool sounding units. A lot of fun to play around
with. And apparently they're somewhat rare because I've seen more than
one of them sell for over $400 on eBay within the past couple of
years. Do you have the version with 1/4" inputs/outputs, or is yours
XLR? I think the XLR ("studio") version is the _very_ rare one.



I have the 1/4" version. I think I made the mistake of leaving it on
all the time since there is no off switch on the front.
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