I did something dumb, my Marantz is not happy

[Doug Sterlina]

So I got my "new" Marantz 2270 serial no 11754 and decided it would be
a good idea to check the DC offset. One channel was at 70mV and the
other was at 30mV. Not bad, but enough to bug me since it seemed like
a simple enough fix. I found the manual online and was first going to
check the voltage on J802 like it says. Well I managed to short out
J802 to the ground (puff of smoke came from somewhere around the
middle cap). I turned it off and back on and everything seemed to work
fine so I proceeded to get the offset to 0 for both channels. Now one
channel (either one) will randomly get fuzzy and eventually die until
I crank up the volume and bring it back down. All the voltages on P800
still seem okay. Any chance it's the offset resistors that are the
problem? Could I have killed something on the filter board? It happens
on both AUX and FM, I dont have a turntable yet so I can't test the
phono input.

[Trevor Wilson]

"Doug Sterlina" > wrote in message
oups.com...
> So I got my "new" Marantz 2270 serial no 11754 and decided it would be
> a good idea to check the DC offset. One channel was at 70mV and the
> other was at 30mV. Not bad, but enough to bug me since it seemed like
> a simple enough fix. I found the manual online and was first going to
> check the voltage on J802 like it says. Well I managed to short out
> J802 to the ground (puff of smoke came from somewhere around the
> middle cap). I turned it off and back on and everything seemed to work
> fine so I proceeded to get the offset to 0 for both channels. Now one
> channel (either one) will randomly get fuzzy and eventually die until
> I crank up the volume and bring it back down. All the voltages on P800
> still seem okay. Any chance it's the offset resistors that are the
> problem? Could I have killed something on the filter board? It happens
> on both AUX and FM, I dont have a turntable yet so I can't test the
> phono input.
>

**I don't have a 2270 service manual to hand, but, if you have smoked an
output stage (and it sound like you have), then, if you have to ask how to
repair it, you should not attempt to do so.

Give it to a pro to fix.


--
Trevor Wilson
www.rageaudio.com.au



--
Posted via a free Usenet account from http://www.teranews.com

[Arny Krueger]

"Trevor Wilson" > wrote in
message
> "Doug Sterlina" > wrote in message
> oups.com...
>> So I got my "new" Marantz 2270 serial no 11754 and
>> decided it would be a good idea to check the DC offset.
>> One channel was at 70mV and the other was at 30mV. Not
>> bad, but enough to bug me since it seemed like a simple
>> enough fix. I found the manual online and was first
>> going to check the voltage on J802 like it says. Well I
>> managed to short out J802 to the ground (puff of smoke
>> came from somewhere around the middle cap). I turned it
>> off and back on and everything seemed to work fine so I
>> proceeded to get the offset to 0 for both channels. Now
>> one channel (either one) will randomly get fuzzy and
>> eventually die until I crank up the volume and bring it
>> back down. All the voltages on P800 still seem okay. Any
>> chance it's the offset resistors that are the problem?
>> Could I have killed something on the filter board? It
>> happens on both AUX and FM, I dont have a turntable yet
>> so I can't test the phono input.
>
> **I don't have a 2270 service manual to hand, but, if you
> have smoked an output stage (and it sound like you have),
> then, if you have to ask how to repair it, you should not
> attempt to do so.
> Give it to a pro to fix.

Totally agreed. Fixing a SS output stage that has been smoked can be
remarkably complex. The smoke is usually pretty expensive. The cost of even
fairly trivial errors is more smoke.

[Doug Sterlina]

Great. I was told on another forum to check the speaker protection
relay so hopefully it's just that. I dont think I'm that lucky though.
Here is a link to the service manual if anyone wants it.
http://www.hifiengine.com/download_centre/index.php?marantz_2270_service.pdf

[Arny Krueger]

"Doug Sterlina" > wrote in message
oups.com

> Great.

Not encouraging, but based on a lot of experience with fixing SS power amps.

The Marantz output stage is a pretty straight-forward full-complementary
circuit. The protection circuit (H705-H708) looks a little more complex than
most. More hair-trigger than standard, it appears.

> I was told on another forum to check the speaker
> protection relay so hopefully it's just that.

Dream on.

> I dont think I'm that lucky though. Here is a link to the
> service manual if anyone wants it.
> http://www.hifiengine.com/download_centre/index.php?marantz_2270_service.pdf

Thanks for the link. I always wondered what the schematic looked like. This
was a quality piece - little was spared given the technology of the day.

[Eeyore]

Doug Sterlina wrote:

> Great. I was told on another forum to check the speaker protection
> relay so hopefully it's just that.

That merely proves how common bad advice is.

Graham

[News]

"Eeyore" > wrote in message
...
>
>
> Doug Sterlina wrote:
>
>> Great. I was told on another forum to check the speaker protection
>> relay so hopefully it's just that.
>
> That merely proves how common bad advice is.
>
> Graham
>

The conundrum is: "Why is common sense called common sense when sense is
*not* very common?"

TT ;-)

[George M. Middius]

TTTT said:

> > That merely proves how common bad advice is.

> The conundrum is: "Why is common sense called common sense when sense is
> *not* very common?"

Don't forget to whack Poopie on his hindquarters. Take this to heart:
http://www.lazy-lranch.com/stubborn.gif




--

Krooscience: The antidote to education, experience, and excellence.

[TT]

"George M. Middius" <cmndr _ george @ comcast . net> wrote in message
...
>
>
> TTTT said:
>
>> > That merely proves how common bad advice is.
>
>> The conundrum is: "Why is common sense called common sense when sense is
>> *not* very common?"
>
> Don't forget to whack Poopie on his hindquarters. Take this to heart:
> http://www.lazy-lranch.com/stubborn.gif
>

Ahhhh...... the old "You can drag an Arny to analog but you can't make him
give up his old CDP101 eh?"

Cheers TT :-))

[Eeyore]

TT wrote:

> "George M. Middius" wrote
> > TTTT said:
> >
> >> > That merely proves how common bad advice is.
> >
> >> The conundrum is: "Why is common sense called common sense when sense is
> >> *not* very common?"
> >
> > Don't forget to whack Poopie on his hindquarters. Take this to heart:
> > http://www.lazy-lranch.com/stubborn.gif
> >
>
> Ahhhh...... the old "You can drag an Arny to analog but you can't make him
> give up his old CDP101 eh?"

Does he still have one.

They were truly shockingly bad.

Graham

[TT]

"Eeyore" > wrote in message
...
>
>
> TT wrote:
>
>> "George M. Middius" wrote
>> > TTTT said:
>> >
>> >> > That merely proves how common bad advice is.
>> >
>> >> The conundrum is: "Why is common sense called common sense when sense
>> >> is
>> >> *not* very common?"
>> >
>> > Don't forget to whack Poopie on his hindquarters. Take this to heart:
>> > http://www.lazy-lranch.com/stubborn.gif
>> >
>>
>> Ahhhh...... the old "You can drag an Arny to analog but you can't make
>> him
>> give up his old CDP101 eh?"
>
> Does he still have one.
>
> They were truly shockingly bad.
>
> Graham
>

Not only does he still have one BUT rates it as very good.

http://www.pcavtech.com/play-rec/Sony_CDP-101/index.htm

Now I have said this before about Arny "If all CD players sound the same
(i.e. perfect) shouldn't they be rated as perfect and more perfect? ;-)

With the "Perfect Sound Forever" CDP101 no wonder many people are returning
to "dragging a rock through a ditch" to listen to music again!

Cheers TT

[Trevor Wilson]

"Arny Krueger" > wrote in message
. ..
> "Doug Sterlina" > wrote in message
> oups.com
>
>> Great.
>
> Not encouraging, but based on a lot of experience with fixing SS power
> amps.
>
> The Marantz output stage is a pretty straight-forward full-complementary
> circuit. The protection circuit (H705-H708) looks a little more complex
> than most. More hair-trigger than standard, it appears.
>
>> I was told on another forum to check the speaker
>> protection relay so hopefully it's just that.
>
> Dream on.
>
>> I dont think I'm that lucky though. Here is a link to the
>> service manual if anyone wants it.
>> http://www.hifiengine.com/download_centre/index.php?marantz_2270_service.pdf
>
> Thanks for the link. I always wondered what the schematic looked like.
> This was a quality piece - little was spared given the technology of the
> day.

**Indeed. An unusual amp, in that it was Japanese manufactured, but used
Motorola output devices. Which in itself ended being a bad thing. Those
early aluminium TO3 packs were pretty average longevity-wise. They'd often
come in with tiny little holes in the aluminium case, where the white hot
silicon escaped from the case at high velocity. You don't find that with
steel cases.


--
Trevor Wilson
www.rageaudio.com.au



--
Posted via a free Usenet account from http://www.teranews.com

[Trevor Wilson]

"Doug Sterlina" > wrote in message
oups.com...
> Great. I was told on another forum to check the speaker protection
> relay so hopefully it's just that. I dont think I'm that lucky though.

**That's kinda like checking the power switch, because it won't turn on. An
alternative allegory would be to lose your wallet 100 Metres away from a
street light, but spending all your time looking for it directly underneath
that street light.

> Here is a link to the service manual if anyone wants it.
> http://www.hifiengine.com/download_centre/index.php?marantz_2270_service.pdf

**Thanks. The 2270 is one of the few old Marantz manuals I don't have. And I
have a couple of hundred.


--
Trevor Wilson
www.rageaudio.com.au



--
Posted via a free Usenet account from http://www.teranews.com

[west[_4_]]

"Doug Sterlina" > wrote in message
oups.com...
> Great. I was told on another forum to check the speaker protection
> relay so hopefully it's just that. I dont think I'm that lucky though.
> Here is a link to the service manual if anyone wants it.
>
http://www.hifiengine.com/download_centre/index.php?marantz_2270_service.pdf

Doug: This link, for unknown reasons, was forbidden for me to open.
Perhaps you can try a different approach for this link. I'm usually not too
bad in troubleshooting complex circuits.

west

[Doug Sterlina]

I shouldnt have linked to the pdf. Looks like the URL changed. Here is
the actual page its on.

http://www.hifiengine.com/manuals_type.php?make=Marantz&selected_model=2270

Tell me if that works. Thanks for all the help so far. Im thinking
about replacing all the caps (with help from an EE) because im sure
they are due for it. It would be nice to get it working though.

[west[_4_]]

"Doug Sterlina" > wrote in message
ups.com...
> I shouldnt have linked to the pdf. Looks like the URL changed. Here is
> the actual page its on.
>
>
http://www.hifiengine.com/manuals_type.php?make=Marantz&selected_model=2270
>
> Tell me if that works. Thanks for all the help so far. Im thinking
> about replacing all the caps (with help from an EE) because im sure
> they are due for it. It would be nice to get it working though.

Cardinal sin in troubleshooting. Never change parts for the sake of
upgrading because in the process you can compound your problem. Find your
problem first, then repair it. When everything is working, then, if you
want, upgrade the caps, a couple at a time and make adjustments in small
increments to check your work.
Your link is 32 pages. Tell me where is J802 to save me some time. Thanks.

west
>

[Doug Sterlina]

Page 23 bottom right is the P800 board with J802 and J803. Another
version is on page 30, but J802 and J803 appear to both be grounded in
that diagram.
Page 13 has the instructions I was following.

Doug

[Doug Sterlina]

Is there any specific brand of capacitors that I should use to replace
original Marantz caps? I am going to replace the capacitors and relay
on the P800 board since that is where the smoke came out of.