Sherwood RX-5502 Receiver Protection Shutdown, Repair, thoug

[Franc Zabkar]

On Thu, 13 Oct 2011 09:03:39 -0700 (PDT), "William R. Walsh"
<wm_walsh@hotmail.com> put finger to keyboard and composed:

But I would think that adding a bit of series
resistance to the input side and letting some of the waste
heat go away there would go a long way towards extending the
life of the regulator package.

I had not thought of this and might just sit down and do the math to
see what I'd need. What I do will depend upon whether or not there is
room to put something in place without going to extremes.

I agree that's the simplest solution. In fact I've done similar things
in lots of gear, including a 586 motherboard.

- Franc Zabkar
--
Please remove one 'i' from my address when replying by email.

 

[William R. Walsh]

Hi!

These Murata parts are about $4.50 each in onesies, through Mouser.

If I've found the right part, I reckon you are speaking of the 7812SR/
SRH-C regulators. These look like interesting devices but the low
current rating may be a problem. I need to rig up a way to see what
the current draw actually is.

I don't think noise in the circuit would be a problem, this regulator
appears to be powering a protection circuit. I've not traced the
circuit to know exactly what it's powering beyond that.

William

 

[Uffe Bćrentsen]

Den 12-10-2011 19:05, William R. Walsh skrev:

Hello all...

This is part of a longer story which I won't get into now. Suffice it
to say that I've wanted to get my hands on a failed Sherwood RX-4105
or RX-4109 stereo receiver to see just what it is that kills
them...abuse, misuse, weak parts, bad engineering/quality control or
something else. I've never had any luck coming into a truly broken
one, but someone recently gave me an RX-5502 that would just shut down
right after power on. I've been very happy with all of the RX-4105 and
4109 units I own.

The RX-5502 is a so-called multi-zone receiver. That is to say it can
support up to eight connected pairs of speakers, with four of the
pairs playing a different ("room 2") source if that is desired. It has
two complete stereo amplifiers in place, each one claimed to have an
output power of 100 watts per channel. (Obviously they're dreaming if
they think that this receiver is ever going to output 400 total watts
of power without catching fire, but...) This example was manufactured
sometime in 2008.

As found, this set would indeed power on for a few seconds, and shut
down with a blinking standby LED. I started checking things out. In
this set, the amplifier board is separate from the main board, so this
was not terribly hard to do. Every power device tested good with a
simple ohmmeter check, and nothing looked burnt or distressed on the
amp board. This doesn't look like a case of a failed power transistor
to me.

I'm working without service literature or even a schematic as Sherwood
would not provide them, but there is printing on the board that
identifies what each conductor in the ribbon cable going to the amp
board is used for. This set has a "test mode", and unlike similar
models, the "test mode" allows the power to stay on indefinitely while
the display test is running. Testing for voltages is a lot nicer
without having to constantly turn the set back on again! Voltages are
what I'd expect for B+ and B-, but a twelve volt input to the board is
hovering around a few hundred millivolts at most. That could do it!

Removing the amplifier board from the system and running without it
was probably risky, but it seemed like a worthwhile thing to do. With
the amp board removed, there was still no voltage from the +12 volt
connection. It still hovered around 300mV with the set on.
Interestingly, every now and then, a good power up was possible with
the amp board out, and the set would come out of protection.
Okay...where is the +12 volt supply generated?

Over in the power supply section there are a few linear voltage
regulators--two heatsinked 7812s and one freestanding 7912. One 7812
and the 7912 are doing their jobs, but the other 7812 is cold to the
touch and does not seem to be doing anything. (In fact, it was putting
out 300mV when I later checked it.)

Replacing the failed 7812 with an LM340 solved the problem. The set
immediately came back to life with the amp board in place, and it
plays. It appears, based on simple observation, that one 7812 is
powering the coils leading up to the speaker selection/protection
relays and the other is powering the amp board itself. What other
loads might be powered by these regulators has not been determined.

While the set is working, I don't like the temperature at which the
new regulator is running. Within ten minutes, its heatsink is on the
verge of being too hot to touch for more than a few seconds. There is
evidence on the circuit board that these regulators have always run
very hot. I've been in touch with Sherwood America, who said "the
regulator may become too hot to touch and possibly fail". I strongly
suspect there are bad capacitors on the amp and main boards, which
will need to be replaced and may be stressing the regulator. Yet
Sherwood seems to be saying that the extremely hot operation is
*normal* here. (However, it should be said that there is something of
a language barrier with the folks I've been communicating with.)

I could install a fan above or larger heatsink on the regulator and
I'm not above doing it if that is just the way things will be. I
suspect that would force the regulator to operate more reliably.

What I really want to know, though, is whether or not a drop-in
replacement with more current delivering capability than the LM340 or
78xx series exists. I've looked halfheartedly over the years but never
found anything. I could always build a more capable regulator board
and hack it in there, but I don't really feel like doing that. A fan
would be easier and faster.

I'd also like to know if anyone has had an RX-5502 on their repair
bench, and if they could comment on just how hot its regulators were
running. Any thoughts would be very much appreciated!

Replace the burning hot 7812 with one of these:

http://www.dimensionengineering.com/datasheets/DE-SWADJ.pdf

I have no connection to the company only thinks their product is sweet.

--
Uffe Bćrentsen

 

[T Wood]

responding to
http://www.electrondepot.com/repair/sherwood-rx-5502-receiver-protection-shutdown-repair-thoug-134725-.htm
, T Wood wrote:
Thank you so much for the info. I found the 7812 that powered the amp to be
bad. A $2 radio shack part and a little time, and my RX-5502 is back up and
operational. Mine was shutting down exactly as you described and after
replacing the 7812, it has played music for over two hours and is still doing
great.

 

You realize this is five years old and some of these people could be dead.

It might be nice to resurrect threads on websites that simply copy Usenet but have no content of their own, but to respond to it on Usenet is not nice. Some people get pissed off.

Some people pull up shit from like 1991. this was even here in 1991 ? I mean, some cars still had carbs back then. They never heard of radon gas. Like a different world.

 

[Kaz Kylheku]

On 2016-01-14, jurb6006@gmail.com <jurb6006@gmail.com> wrote:

You realize this is five years old and some of these people could be
dead.

It might be nice to resurrect threads on websites that simply copy
Usenet but have no content of their own, but to respond to it on
Usenet is not nice. Some people get pissed off.

Threads about a fixing particular piece of consumer electronic equipment
tend to be old.

If someone has *new* information to add, like "I fixed a similar problem
with the same unit, and it went like this" it's perfectly fine;
there is nothing wrong with referencing the old thread.

Look, you're just not going to find a current, continuous, day-to-day
discussion thread on a darned Sherwood RX-5502, right?

But if you start trying to help that person from seven years ago by
asking questions, like "does the front panel light up, or is it
completely dead?" then you're indeed a necroposting moron who annoys
people, and probably shouldn't be using any device that has a CPU
and network connection.

Some people pull up shit from like 1991. this was even here in 1991 ?
I mean, some cars still had carbs back then. They never heard of radon
gas. Like a different world.

I'm pretty sure I heard of the issue of radon in homes in the middle
1980's. I'm in Canada, though; it's more of a problem in winterized
homes, whose residents don't open their damned windows for much of the
year.

Radon was already linked to lung cancer in non-smoking miners in the
1940's, according to <https://en.wikipedia.org/wiki/Radon#Health_risks>.

 

I don't know how you get here, but Google and aioe or whatever seem to be the only free ways to do it. Actually I probably should get a paid service but then, who gets that money ? Originally I got here via AOL but they stopped doing everything I wanted so I got rid of them.

Anyway, in Google the topics are arranged in reverse chronological order, sorted by most recent post. The date is right there, but it gives the latest date. So if it bugs you it bugs me more because I see on the right it says "4 hours ago", then I open it up and it does not skip the old posts because I have not read them through Google. Believe it or not I may have read or even be in some of these old posts. But that doesn't matter, most of my work was TVs so therefore it is all useless knowledge. Audio equipment is a different story. People are repairing and restoring old stuff every day, to the tune of mucho dinero I might add. One guy I did a job for in PA wound up with $600 into the repair. Half of that was the round trip on UPS, and they broke it ! I actually could have charged him more but I have him some money off because I put a scuff mark on the front panel. It is a Mitsubishi X-11 system with the vertical turntable. I had to fix the amp which meant retrofitting it to modern chips because the original is unobtanium, but before that I had to fix the power supply with a foil burnt off the board, which was quite worrisome at first. I had to fix a broken part in the cassette deck and put belts in that. Then when it got home, UPS somehow screwed up the TT tracking servo. I had to charge him another hundred for that but that included time and gas to meet him about halfway. We were not about to do UPS again. so about $700 for like a 25 watt per channel, magnetic cartridge (oh I replaced that also) and a pretty decent cassette deck. Although he'll never need outputs again, I used LM3886s.

At any rate, back to our regularly scheduled hijack, the people who respond to these old posts, like you said, must be finding them through a search. I mean a web search. for them to search SER, they would have to go to SER first, right ?

However, I just Googled for "Sherwood RX-5502" and no hits with "groups" on the first two pages. [

Then there is another thing, a bunch of websites archive Usenet and pretend they got a forum. Could they be finding these old posts that way ?

I mostly agree with you, but not with the preventing replies to posts over a month old. I think six months would be good. At least there's a good chance the people are still alive.

 

[Michael Black]

On Thu, 14 Jan 2016, Kaz Kylheku wrote:

On 2016-01-14, jurb6006@gmail.com <jurb6006@gmail.com> wrote:
You realize this is five years old and some of these people could be
dead.

It might be nice to resurrect threads on websites that simply copy
Usenet but have no content of their own, but to respond to it on
Usenet is not nice. Some people get pissed off.

Threads about a fixing particular piece of consumer electronic equipment
tend to be old.

If someone has *new* information to add, like "I fixed a similar problem
with the same unit, and it went like this" it's perfectly fine;
there is nothing wrong with referencing the old thread.

No it's not fine.

This is not google, where the messages all appear. usenet was never
intended to be archived.

SOme idiot replying to an old thread isn't being part of the newsgroup,
they are simply doing google.

ANd whether or not that's good, the blunders pile on. They don't quote,
they don't acknowledge they are replying to an old message, they may not
even have a proper subject header (so instead of "re:" so we know it's a
reply, it can often look like the start of a thread. Without quoting,
there's no context, the only reason the post makes sense is because other
idiots before them have done the same thing, so it's most likely a google
idiot post.

The reality is people are replying to old threads for reasons that aren't
clear, but I suspect some of it is that they simply don't grasp where they
are, or that they are replying to an old thread.

And too often, someone replies to an old thread, and others jump in as if
the thread is new, because they are reading at google and the thread then
"comes to the top" and starts replying to the old thread. Too often,
those people haven't even read the old thread, so they are not adding
anything to it. Or, the person replying to the old thread gets replies,
again as if the thread is new. Often the old thread has covered the
problem, and anything new is just repetition. We had a resurrected thread
last year here, and it wasn't so old, so some of the original participants
replied, a second time, and gave about the same answer as they did the
first (and in that thread, the original poster had posted a followup, back
then, to reveal what solution had worked for them).


That's on top of the stupid posts where people ask a 1991 post "is this
thing still for sale?" or the like. Don't try to justify this based on a
specific newsgroup, the problem is that google still hasn't fixed the bug
that allows replies to messages older than 30 days.

You want everything neat and tidy in one place, but that doesn't happen.
And the same search that found the original thread should indeed find any
separate followup thread that someone posted much later.

Our place here isn't to deal with the future, at google, our place here is
an ongoing discussion of the repair of electronic equipment (or whatever
the newsgroup is intended for, if this was another newsgroup).

Look, you're just not going to find a current, continuous, day-to-day
discussion thread on a darned Sherwood RX-5502, right?

You're assuming that people only ask about current equipment.

I've read this newsgroup since late 1994, and when I got full internet
access in 1996, dejanews had already started archiving usenet posts. That
was neat, because every time I dragged home some neat piece of equipment
from a garage or rummage sale, I'd do a search, and often find some bit of
information about the new junk. If I'd needed to ask something, I'd not
reply to an old thread (and that option wasn't there with dejanews).

But if I'd wanted to ask about something I just dragged home, I'd post
away. And maybe someone would have information, maybe not, it depends on
who is reading the newsgroup.

Any of the idiots who keep replying to old threads is welcome to be a
member of this newsgroup, all they have to do is post a message, if they
want to talk about something old, that's okay too. Just don't reply to an
old message.

But if you start trying to help that person from seven years ago by
asking questions, like "does the front panel light up, or is it
completely dead?" then you're indeed a necroposting moron who annoys
people, and probably shouldn't be using any device that has a CPU
and network connection.

But when some idiot replies to an old post, here it's not so obvious
(except because there are telltales that we notice after the repeated
abuse), so others chime in to the old thread as if it is new. So whether
or not the first replier has some good thing to add, it's distruptive to
the newsgroup.

Forget about google, act here like this is Usenet, which it is. Messages
fade with time, unless someone saves them to their own hard drive. It's
nto intended to be a long term medium. So don't treat it like it is.

Anyone can post and say "there was a discussion ten years ago, and I
thought I'd add some more insight", they can even reference the old
message, or "I just got this new thing, so I thought I'd post some
comments about it". They don't need to rely on someone previously posting
about it.

Michael

 

[T Wood]

responding to
http://www.electrondepot.com/repair/sherwood-rx-5502-receiver-protection-shutdown-repair-thoug-134725-.htm
, T Wood wrote:

I just wanted to say thank you. I didn't realize that was so bad!!

 

[Michael A. Terrell]

jurb6006@gmail.com wrote:

I don't know how you get here, but Google and aioe or whatever seem to be the only free ways to do it. Actually I probably should get a paid service but then, who gets that money ? Originally I got here via AOL but they stopped doing everything I wanted so I got rid of them.

There are a lot of free, or dirt cheap NNTP servers. It is included
with any Earthlink account and I can set up, up to eight Usenet accounts
with my Broadband account. One for each Email account.

 

T Wood wrote: "electrodepot.com. I replied through that web site. I have no idea what Usenet
is. I just know there is at least one ass that like calling people idiots "


Most folks born after 1980 wouldn't. Basically,
usenet WAS the internet. A worldwide "distributed
discussion system" according to Wikipedia:

https://en.m.wikipedia.org/wiki/Usenet

And many traditional Usenet users become very
irate and take it personal when someone - like
me - interacts with usenet groups via Google or
some other non-standard usenet interface.
What they see coming into the group from
a non-NNTP source is out of the ordinary that
the context of the message is lost.

But still, no reason for them to be jerks about it.

 

[T Wood]

responding to
http://www.electrondepot.com/repair/sherwood-rx-5502-receiver-protection-shutdown-repair-thoug-134725-.htm
, T Wood wrote:

jurb6006 wrote:

I don't know how you get here, but Google and aioe or whatever seem to
be t
he only free ways to do it. Actually I probably should get a paid
service b
ut then, who gets that money ? Originally I got here via AOL but they
stopp
ed doing everything I wanted so I got rid of them.

Anyway, in Google the topics are arranged in reverse chronological
order, s
orted by most recent post. The date is right there, but it gives the
latest
date. So if it bugs you it bugs me more because I see on the right it
says
"4 hours ago", then I open it up and it does not skip the old
posts becaus
e I have not read them through Google. Believe it or not I may have read
or
even be in some of these old posts. But that doesn't matter, most of my
wo
rk was TVs so therefore it is all useless knowledge. Audio equipment is
a d
ifferent story. People are repairing and restoring old stuff every day,
to
the tune of mucho dinero I might add. One guy I did a job for in PA
wound u
p with $600 into the repair. Half of that was the round trip on UPS, and
th
ey broke it ! I actually could have charged him more but I have him some
mo
ney off because I put a scuff mark on the front panel. It is a
Mitsubishi X
-11 system with the vertical turntable. I had to fix the amp which meant
re
trofitting it to modern chips because the original is unobtanium, but
befor
e that I had to fix the power supply with a foil burnt off the board,
which
was quite worrisome at first. I had to fix a broken part in the
cassette d
eck and put belts in that. Then when it got home, UPS somehow screwed up
th
e TT tracking servo. I had to charge him another hundred for that but
that
included time and gas to meet him about halfway. We were not about to do
UP
S again. so about $700 for like a 25 watt per channel, magnetic
cartridge (
oh I replaced that also) and a pretty decent cassette deck. Although
he'll
never need outputs again, I used LM3886s.

At any rate, back to our regularly scheduled hijack, the people who
respond
to these old posts, like you said, must be finding them through a
search.
I mean a web search. for them to search SER, they would have to go to
SER f
irst, right ?

However, I just Googled for "Sherwood RX-5502" and no hits
with "groups" on
the first two pages. [

Then there is another thing, a bunch of websites archive Usenet and
pretend
they got a forum. Could they be finding these old posts that way ?

I mostly agree with you, but not with the preventing replies to posts
over
a month old. I think six months would be good. At least there's a good
chan
ce the people are still alive.

If you really care to know--I did a goggle search and found the info on
electrodepot.com. I replied through that web site. I have no idea what Usenet
is. I just know there is at least one ass that like calling people idiots

 

On Wednesday, January 13, 2016 at 11:37:04 PM UTC-5, T Wood wrote:

responding to
http://www.electrondepot.com/repair/sherwood-rx-5502-receiver-protection-shutdown-repair-thoug-134725-.htm
, T Wood wrote:
Thank you so much for the info. I found the 7812 that powered the amp to be
bad. A $2 radio shack part and a little time, and my RX-5502 is back up and
operational. Mine was shutting down exactly as you described and after
replacing the 7812, it has played music for over two hours and is still doing
great.

I have had the same problem with my RX-5502. Can you tell me what the $2 Radio Shack part is? I looked at the thread you quoted and did not see a reference to the part name or number. Thanks!

 

[John-Del]

On Sunday, March 4, 2018 at 3:02:22 PM UTC-5, jos...@cypressfilms.com wrote:

On Wednesday, January 13, 2016 at 11:37:04 PM UTC-5, T Wood wrote:
responding to
http://www.electrondepot.com/repair/sherwood-rx-5502-receiver-protection-shutdown-repair-thoug-134725-.htm
, T Wood wrote:
Thank you so much for the info. I found the 7812 that powered the amp to be
bad. A $2 radio shack part and a little time, and my RX-5502 is back up and
operational. Mine was shutting down exactly as you described and after
replacing the 7812, it has played music for over two hours and is still doing
great.

I have had the same problem with my RX-5502. Can you tell me what the $2 Radio Shack part is? I looked at the thread you quoted and did not see a reference to the part name or number. Thanks!

Honestly, if "7812" and "regulator" don't ring any bells, you probably shouldn't be screwing around with this. It could not have been any more easy unless someone dispatches a courier to your home with one.

 

On Sunday, 4 March 2018 20:02:22 UTC, jos...@cypressfilms.com wrote:

On Wednesday, January 13, 2016 at 11:37:04 PM UTC-5, T Wood wrote:
responding to
http://www.electrondepot.com/repair/sherwood-rx-5502-receiver-protection-shutdown-repair-thoug-134725-.htm
, T Wood wrote:
Thank you so much for the info. I found the 7812 that powered the amp to be
bad. A $2 radio shack part and a little time, and my RX-5502 is back up and
operational. Mine was shutting down exactly as you described and after
replacing the 7812, it has played music for over two hours and is still doing
great.

I have had the same problem with my RX-5502. Can you tell me what the $2 Radio Shack part is? I looked at the thread you quoted and did not see a reference to the part name or number. Thanks!

he told you, the 7812.

 

On Sunday, March 4, 2018 at 6:02:16 PM UTC-5, tabb...@gmail.com wrote:

On Sunday, 4 March 2018 20:02:22 UTC, jos...@cypressfilms.com wrote:
On Wednesday, January 13, 2016 at 11:37:04 PM UTC-5, T Wood wrote:
responding to
http://www.electrondepot.com/repair/sherwood-rx-5502-receiver-protection-shutdown-repair-thoug-134725-.htm
, T Wood wrote:
Thank you so much for the info. I found the 7812 that powered the amp to be
bad. A $2 radio shack part and a little time, and my RX-5502 is back up and
operational. Mine was shutting down exactly as you described and after
replacing the 7812, it has played music for over two hours and is still doing
great.

I have had the same problem with my RX-5502. Can you tell me what the $2 Radio Shack part is? I looked at the thread you quoted and did not see a reference to the part name or number. Thanks!

he told you, the 7812.

Ah, yes. Sorry, for some reason I got it into my head that he replaced it with something different (and better). And to John-Del's point, I have no intention of getting in over my head with this; I am just mad that a product I paid a fair amount of money for stopped working after 4 hours of use. If I can find someone local to fix it, I will. Otherwise I'll move on with my life.

 

What is local ? I fix these things.

 

[Fox's Mercantile]

On 3/6/18 12:16 AM, oldschool@tubes.com wrote:

In the end I was lucky to get about $2 an hour for my
time.

Not a very effective use of your time.

--
"I am a river to my people."
Jeff-1.0
WA6FWi
http:foxsmercantile.com

 

On Mon, 5 Mar 2018 09:41:00 -0800 (PST), joseph@cypressfilms.com wrote:

Thank you so much for the info. I found the 7812 that powered the amp to be
bad. A $2 radio shack part and a little time, and my RX-5502 is back up and
operational. Mine was shutting down exactly as you described and after
replacing the 7812, it has played music for over two hours and is still doing
great.

I have had the same problem with my RX-5502. Can you tell me what the $2 Radio
Shack part is? I looked at the thread you quoted and did not see a reference to
the part name or number. Thanks!

Back in the 70s, I had to repair a Sherwood solid state receiver for
someone that had the same issues. (I dont remember the model). But that
damn thing really pissed me off for days. I finally fixed it, but it
would have cost the owner more than a new stereo if I charged the going
rate per hour. In the end I was lucky to get about $2 an hour for my
time. I was not impressed by Sherwood gear by the time I finished that
one.

 

On Tuesday, 6 March 2018 06:32:03 UTC, Fox's Mercantile wrote:

On 3/6/18 12:16 AM, oldschool@tubes.com wrote:
In the end I was lucky to get about $2 an hour for my
time.

Not a very effective use of your time.

No, but we've all had jobs where that became true, more so when young.


NT