sci.electronics.repair@googlegroups.com

Today's topics:

* Electronic Kenmore refrigerator not working, what does this sign mean - 11
messages, 7 authors
http://groups.google.com/group/sci.electronics.repair/t/4fe72ade24c7a7db?hl=en
* Yet another bulging-capacitors replacement - 2 messages, 1 author
http://groups.google.com/group/sci.electronics.repair/t/3ec97de65fce9bb3?hl=en
* VCM driver - 1 messages, 1 author
http://groups.google.com/group/sci.electronics.repair/t/59e08ffb8304f775?hl=en
* Technics KN800 MIDI keyboard no sound - 3 messages, 3 authors
http://groups.google.com/group/sci.electronics.repair/t/f95dad92d98851fc?hl=en
* LORAN C - 1 messages, 1 author
http://groups.google.com/group/sci.electronics.repair/t/73c2d1e0342e191b?hl=en
* Technics SA-310 Receiver Fixed! - 2 messages, 2 authors
http://groups.google.com/group/sci.electronics.repair/t/266f00b3a43b6910?hl=en

==============================================================================
TOPIC: Electronic Kenmore refrigerator not working, what does this sign mean
http://groups.google.com/group/sci.electronics.repair/t/4fe72ade24c7a7db?hl=en
==============================================================================

== 1 of 11 ==
Date: Tues, Aug 31 2010 6:07 pm
From: "William R. Walsh"

Hi!

That wouldn't be an indication of a "child safety lock" would it?

If so, try holding each button down for a few seconds to see if one shuts it
off. I'd think that maybe such a thing would be in the manual, but who
knows?

William

== 2 of 11 ==
Date: Tues, Aug 31 2010 6:55 pm
From: Steve Barker

On 8/31/2010 6:24 PM, Ignoramus20906 wrote:
> I have an electronic Kenmore refrigerator 596.50013100. I bought it
> from a private party over a year ago and it has been working great
> until now. It seems very well made, overall.
>
> Yesterday it started beeping and displaying a strange trouble signal:
>
> http://igor.chudov.com/tmp/Kenmore-Trouble.jpg
>
> It is right above the word "Kenmore", is red and looks like a crossed
> lock and an exclamation.
>
> The temperature in the unit has been rising since then and clearly, it
> is not cooling anything. Right now both freezer and fridge are at 46
> degrees F.
>
> I tried calling Kenmore, but could only speak to dummies who are
> forbidden to give any diagnostics.
>
> My question is WTF does this sign mean? It is meant to tell me
> something.
>
> Thanks
>
> i

Well it may just be the picture, but it looks like the freezer is set to
45 degrees.

--
Steve Barker
remove the "not" from my address to email

== 3 of 11 ==
Date: Tues, Aug 31 2010 6:59 pm
From: Ignoramus20906

On 2010-09-01, Steve Barker <ichasetrains@notgmail.com> wrote:
> On 8/31/2010 6:24 PM, Ignoramus20906 wrote:
>> I have an electronic Kenmore refrigerator 596.50013100. I bought it
>> from a private party over a year ago and it has been working great
>> until now. It seems very well made, overall.
>>
>> Yesterday it started beeping and displaying a strange trouble signal:
>>
>> http://igor.chudov.com/tmp/Kenmore-Trouble.jpg
>>
>> It is right above the word "Kenmore", is red and looks like a crossed
>> lock and an exclamation.
>>
>> The temperature in the unit has been rising since then and clearly, it
>> is not cooling anything. Right now both freezer and fridge are at 46
>> degrees F.
>>
>> I tried calling Kenmore, but could only speak to dummies who are
>> forbidden to give any diagnostics.
>>
>> My question is WTF does this sign mean? It is meant to tell me
>> something.
>>
>> Thanks
>>
>> i
>
> Well it may just be the picture, but it looks like the freezer is set to
> 45 degrees.
>

It is not "set" to 45 degrees, what was displayed is the current
temperature.

i

== 4 of 11 ==
Date: Tues, Aug 31 2010 7:18 pm
From: Ignoramus20906

Here are my findings:

1) The condenser fan is running fine
2) The compressor motor buzzes, then overload stops it, to restart in
a few minutes
3) The compressor motor is HOT
4) Inside of the relay does not look burned.

I see four possibilities:

1) The capacitor is bad
2) Something in the relay assembly is bad (unlikely, since this seems
to be a run capacitor).
3) Somehow the compressor cannot pump, due to problems with cooling
coils or whatever other internal blockage
4) [the most dreaded possibility] the compressor is seized.

To eliminate 1-2, I have ordered a new capacitor and a new relay
assembly (since I broke some holding plastic lugs when removing
it). The cost was relatively small ($34.95 for everything with
shipping).

Hopefully, I will get that stuff around Monday (they are in CA, I am
in IL).

We can live with it, because it is our second (garage) fridge, and we
also have a upright freezer.

If that does not help, I would expect this to become an expensive
repair, and I would have to call a tech to replace the compressor, or
even junk the fridge.

i

== 5 of 11 ==
Date: Tues, Aug 31 2010 7:33 pm
From: ignator

On Aug 31, 5:24 pm, Ignoramus20906 <ignoramus20...@NOSPAM.
20906.invalid> wrote:
> I have an electronic Kenmore refrigerator 596.50013100. I bought it
> from a private party over a year ago and it has been working great
> until now. It seems very well made, overall.
>
> Yesterday it started beeping and displaying a strange trouble signal:
>
>          http://igor.chudov.com/tmp/Kenmore-Trouble.jpg
>
> It is right above the word "Kenmore", is red and looks like a crossed
> lock and an exclamation.
>
> The temperature in the unit has been rising since then and clearly, it
> is not cooling anything. Right now both freezer and fridge are at 46
> degrees F.
>
> I tried calling Kenmore, but could only speak to dummies who are
> forbidden to give any diagnostics.
>
> My question is WTF does this sign mean? It is meant to tell me
> something.
>
> Thanks
>
> i

I'm confused, if its electronic then it would be thermo-electric, and
not have a condenser, evaporator, or compressor. But as you have
indicated it has these. So I'm guessing the electronic, is the
electronic thermostat only. You indicated the compressor is hot.
Sounds like the start relay is fubar, and some current limit does not
trip a clicks-on switch. And start relay is now a misnomer as these
have been replaced with thermistors. Most likely this is the faulted
device. There should be a wiring diagram on the back side of this
refrigerator, hope it does. If it's a defrost problem the diagram
would show this circuit.
ignator

== 6 of 11 ==
Date: Tues, Aug 31 2010 7:33 pm
From: ignator

On Aug 31, 5:24 pm, Ignoramus20906 <ignoramus20...@NOSPAM.
20906.invalid> wrote:
> I have an electronic Kenmore refrigerator 596.50013100. I bought it
> from a private party over a year ago and it has been working great
> until now. It seems very well made, overall.
>
> Yesterday it started beeping and displaying a strange trouble signal:
>
>          http://igor.chudov.com/tmp/Kenmore-Trouble.jpg
>
> It is right above the word "Kenmore", is red and looks like a crossed
> lock and an exclamation.
>
> The temperature in the unit has been rising since then and clearly, it
> is not cooling anything. Right now both freezer and fridge are at 46
> degrees F.
>
> I tried calling Kenmore, but could only speak to dummies who are
> forbidden to give any diagnostics.
>
> My question is WTF does this sign mean? It is meant to tell me
> something.
>
> Thanks
>
> i

I'm confused, if its electronic then it would be thermo-electric, and
not have a condenser, evaporator, or compressor. But as you have
indicated it has these. So I'm guessing the electronic, is the
electronic thermostat only. You indicated the compressor is hot.
Sounds like the start relay is fubar, and some current limit does not
trip a clicks-on switch. And start relay is now a misnomer as these
have been replaced with thermistors. Most likely this is the faulted
device. There should be a wiring diagram on the back side of this
refrigerator, hope it does. If it's a defrost problem the diagram
would show this circuit.
ignator

== 7 of 11 ==
Date: Tues, Aug 31 2010 7:37 pm
From: gpsman

On Aug 31, 7:24 pm, Ignoramus20906 <ignoramus20...@NOSPAM.
20906.invalid> wrote:
> I have an electronic Kenmore refrigerator 596.50013100. I
>
> Yesterday it started beeping and displaying a strange trouble signal:
>
>          http://igor.chudov.com/tmp/Kenmore-Trouble.jpg

Reboot and call me in the morning.
-----

- gpsman

== 8 of 11 ==
Date: Tues, Aug 31 2010 7:47 pm
From: Ignoramus20906

On 2010-09-01, ignator <fredhababorbitz@hotmail.com> wrote:
> On Aug 31, 5:24?pm, Ignoramus20906 <ignoramus20...@NOSPAM.
> 20906.invalid> wrote:
>> I have an electronic Kenmore refrigerator 596.50013100. I bought it
>> from a private party over a year ago and it has been working great
>> until now. It seems very well made, overall.
>>
>> Yesterday it started beeping and displaying a strange trouble signal:
>>
>> ? ? ? ? ?http://igor.chudov.com/tmp/Kenmore-Trouble.jpg
>>
>> It is right above the word "Kenmore", is red and looks like a crossed
>> lock and an exclamation.
>>
>> The temperature in the unit has been rising since then and clearly, it
>> is not cooling anything. Right now both freezer and fridge are at 46
>> degrees F.
>>
>> I tried calling Kenmore, but could only speak to dummies who are
>> forbidden to give any diagnostics.
>>
>> My question is WTF does this sign mean? It is meant to tell me
>> something.
>>
>> Thanks
>>
>> i
>
> I'm confused, if its electronic then it would be thermo-electric, and
> not have a condenser, evaporator, or compressor. But as you have
> indicated it has these. So I'm guessing the electronic, is the
> electronic thermostat only.

Electronic control panel with pretty buttons.

> You indicated the compressor is hot.

Yes.

> Sounds like the start relay is fubar, and some current limit does not
> trip a clicks-on switch. And start relay is now a misnomer as these
> have been replaced with thermistors.

Yes, there is a thermistor puck inside the relay assembly.

> Most likely this is the faulted device. There should be a wiring
> diagram on the back side of this refrigerator, hope it does. If
> it's a defrost problem the diagram would show this circuit. ignator

== 9 of 11 ==
Date: Tues, Aug 31 2010 7:59 pm
From: Archon

On 8/31/2010 10:47 PM, Ignoramus20906 wrote:

>
>> Sounds like the start relay is fubar, and some current limit does not
>> trip a clicks-on switch. And start relay is now a misnomer as these
>> have been replaced with thermistors.
>
> Yes, there is a thermistor puck inside the relay assembly.
>

I had the same problem recently, its the overload relay, actually
thermistors as previously noted.

This thread is for a different model but will help

http://www.applianceblog.com/mainforums/sears-kenmore/742-kenmore-sxs-fridge-bad-relay-compressor.html

Your part would seem to be:-

http://www.partselect.com/PartDetail.aspx?Inventory=2007740&imgID=3&Page=1&SourceCode=7

replacement fixed mine , still running 12 months later.

JC

== 10 of 11 ==
Date: Tues, Aug 31 2010 8:43 pm
From: Ignoramus20906

On 2010-09-01, Archon <Chipbee40_SpamNo@yahoo.com> wrote:
> On 8/31/2010 10:47 PM, Ignoramus20906 wrote:
>
>>
>>> Sounds like the start relay is fubar, and some current limit does not
>>> trip a clicks-on switch. And start relay is now a misnomer as these
>>> have been replaced with thermistors.
>>
>> Yes, there is a thermistor puck inside the relay assembly.
>>
>
> I had the same problem recently, its the overload relay, actually
> thermistors as previously noted.
>
> This thread is for a different model but will help
>
> http://www.applianceblog.com/mainforums/sears-kenmore/742-kenmore-sxs-fridge-bad-relay-compressor.html
>
> Your part would seem to be:-
>
> http://www.partselect.com/PartDetail.aspx?Inventory=2007740&imgID=3&Page=1&SourceCode=7
>
> replacement fixed mine , still running 12 months later.
>
> JC

Archon,

I hope fervently that you are right. I bought those parts:

http://www.appliancepartspros.com/part_details.aspx?part_id=4013414 Part Number: AP4074064
http://www.appliancepartspros.com/part_details.aspx?part_id=4074064 Part Number: AP4013414

Shipped from CA to IL, I will probably get them on Monday. I am very
anxious.

i

== 11 of 11 ==
Date: Tues, Aug 31 2010 11:31 pm
From: "Michael Kennedy"

"Bill" <billnomailnospamx@yahoo.com> wrote in message
news:8e5m4nF5jjU1@mid.individual.net...
> Sometimes there are hidden coils in the freezer. An electric heater on a
> timer will defrost these. If that is not working, it will be a solid block
> of ice.
>
> Try putting all your food in ice chests and let it defrost for 24 hours
> with doors open (unplug it). Then plug it back in and see if it works.
>
> If it works for a few weeks, then same problem again, then suspect the
> defrost heater/timer.
>
> As to fixing, if it is an old refrigerator, get a new one as those save
> electricity and will pay for themselves in 5 years or so.
>

If they last 5 years....

==============================================================================
TOPIC: Yet another bulging-capacitors replacement
http://groups.google.com/group/sci.electronics.repair/t/3ec97de65fce9bb3?hl=en
==============================================================================

== 1 of 2 ==
Date: Tues, Aug 31 2010 6:18 pm
From: "Arfa Daily"

"Jim Yanik" <jyanik@abuse.gov> wrote in message
news:Xns9DE5620083A92jyaniklocalnetcom@216.168.3.44...
> "Arfa Daily" <arfa.daily@ntlworld.com> wrote in
> news:Q_Xeo.1360$c_6.370@newsfe30.ams2:
>
>>
>>
>> "Jeff Liebermann" <jeffl@cruzio.com> wrote in message
>> news:phnn76d5fjpcls7lfscj6t40hehqnc9db4@4ax.com...
>>> On Mon, 30 Aug 2010 05:35:00 -0400, JW <none@dev.null> wrote:
>>>
>>>>On Fri, 27 Aug 2010 20:19:44 -0700 Jeff Liebermann <jeffl@cruzio.com>
>>>>wrote in Message id: <ebug76lk13plippid57h6q6vacu8ve4om9@4ax.com>:
>>>>
>>>>>I don't believe it. The winner of the power hogging consumer CPU
>>>>>contest was the DEC/Intel Alpha 21364 (EV79):
>>>>><http://en.wikipedia.org/wiki/Alpha_21364>
>>>>>which burned 155 watts. Itanium II came close with 130 watts (per
>>>>>core).
>>>
>>>>Check again.
>>>>http://ark.intel.com/Product.aspx?id=43410&processor=9350&spec-codes=S
>>>>LBMX 185W! Gotta love that price as well.
>>>
>>> I stand corrected.
>>> <http://techreport.com/discussions.x/18445>
>>> Some of the reader comments are rather interesting. Still, with any
>>> of these "powerful" processors, a conventional air cooled machine is
>>> going to have a very hot breath and a rather large power supply. I
>>> just don't see this kind of power dissipation in a "dedicated game
>>> machine". Measuring the AC mains power consumption should settle the
>>> matter.
>>>
>>> --
>>> Jeff Liebermann jeffl@cruzio.com
>>
>>
>> Have you any idea just how much processing power it takes to run a
>> user-interactive story in real time, and then to 3D render the
>> graphics in real time ? Do you think that they rate the 12v PSU for
>> 23.5 amps in one version, and 32 amps in the other, for fun ? Those
>> are not real questions, because I know full well when you stop and
>> think about it, you know the answers, Jeff.
>>
>> I've just looked at the rating plate on the bottom of one of the
>> cases, and it is 240v (nominal UK line voltage) at 1.8 amps. I make
>> that a maximum input power of around 430 watts. It's a switching PSU,
>> so I reckon that we can rate that as being at the very worst 80%
>> efficient, so that's still 345 watts potentially going somewhere. I'm
>> prepared to go with 45 watts into ancillary circuitry on the board,
>> which still leaves around 300 watts going somewhere.
>
> that assumes that all the power of the supply is actually used.
> I'm sure there is some reserve capacity there.
>
> "max input power" is not "actual used power".

Well Jim, that was why I used the word "potentially", but judging by the
size of the pins used to couple the power supply's output into the board -
if you've been following the thread, you will recall that I previously
described them as being of the size you would find on the line cord for a
kettle - then I wouldn't say that there was too much in the way of reserve.
Anyway, just think about that premise for a moment. When have you ever known
a manufacturer of a piece of domestic grade electronics, to over-rate any
aspect of it, let alone the power supply, by more than the few percent
required to just about let it scrape by? It's all about cost, and they are
not going to rate the rectifiers and magnetics and filter caps and output
connectors and so on, for any more than they have to, to keep the
manufacturing costs as low as possible ...

Arfa

== 2 of 2 ==
Date: Tues, Aug 31 2010 6:40 pm
From: "Arfa Daily"

"Jeff Liebermann" <jeffl@cruzio.com> wrote in message
news:60aq76t79k66vhdrm6bl3c85js9u20k70s@4ax.com...
> On Tue, 31 Aug 2010 01:26:23 +0100, "Arfa Daily"
> <arfa.daily@ntlworld.com> wrote:
>
>>Have you any idea just how much processing power it takes to run a
>>user-interactive story in real time, and then to 3D render the graphics in
>>real time ?
>
> Well, no. I'm not a power user. What little rendering I do is with
> bacon fat.
>
>>Do you think that they rate the 12v PSU for 23.5 amps in one
>>version, and 32 amps in the other, for fun ? Those are not real questions,
>>because I know full well when you stop and think about it, you know the
>>answers, Jeff.
>
> Actually, I don't know. I don't have any customers with such machines
> and have had zero experience with high power graphic workstations
> (other than early 1980's Applicon CAD stations) or game machines. I
> have worked on various network servers, which do burn such power
> levels. I have looked at a 3D MRI image processor, which had some
> manner of dedicated processor inside, but it certainly wasn't belching
> 400 watts of heat (my estimate by the amount of fan noise).
>
>>I've just looked at the rating plate on the bottom of one of the cases,
>>and
>>it is 240v (nominal UK line voltage) at 1.8 amps. I make that a maximum
>>input power of around 430 watts. It's a switching PSU, so I reckon that we
>>can rate that as being at the very worst 80% efficient, so that's still
>>345
>>watts potentially going somewhere. I'm prepared to go with 45 watts into
>>ancillary circuitry on the board, which still leaves around 300 watts
>>going
>>somewhere. Perhaps I'm being naive, but my best guess is that it's
>>disappearing into the two bloody great BGAs which the manufacturers are
>>trying their utmost to heatsink. If you try to run one of these machines
>>with the heatsinking not in place, it goes into thermal protect in about 5
>>seconds - and all it's doing then is booting. The heatplates on the BGAs
>>are
>>at this point hot enough to take your fingerprints off ...
>>
>>Nope, I'm pretty sure that these two puppies are good for 150 watts
>>apiece,
>>when the machine is doing some real work.
>
> Ok, I stand corrected. I've been assuming that the CPU's are doing
> most of the power dissipation. I didn't think of a dedicated graphics
> processor or whatever the BGA chips are doing. Do you have a gun
> style IR thermometer? I use that to determine if anything is running
> hot. I use a black (non-reflective) cardboard tube attached to the
> lens to prevent it from picking up adjacent components. Incidentally,
> I have yet to find one where the laser dot actually points to where
> the device is measuring when in close proximity. You can also get a
> rough idea of how much effort is going into cooling. If the BGA's
> burn more power than the CPU's, then they're going to need more
> massive heat sinks and better air cooling. At 400 watts, I would
> think they would have gone to heat pipes and external radiators or
> maybe liquid cooling.
>
> Incidentally, I repaired a P4 motherboard yesterday which used Artic
> Silver. My guess is that there was about 5 times as much Artic Silver
> smeared over the CPU (and down the sides where it does nothing) as
> necessary. The stuff down the sides was still fluid, so at $10 for
> 3.5 grams, I saved the excess.
>
>
> --
> Jeff Liebermann jeffl@cruzio.com
> Skype: JeffLiebermann AE6KS 831-336-2558

All of the processing power is in those two BGAs Jeff. They *are* the
processors. One is a dedicated engine that runs the game (or plays a BluRay
disc), as well as handling all the disc I/O - optical and hard - and
internet / network access. On top of this, it manages all of the
housekeeping tasks, so it's doing a lot of work, especially when it's
actually running a game. Modern games have come a long way since the days of
Doom. Most maintain a highly complex 3D 'reality' in which the game is set,
and the gameplay takes place. Just consider for a moment, the highly complex
calculations that have to go on, to work out how potentially many actions
all at once, interact with the 3D model, and the knock-on effects that these
might have on both the gameplay and the graphical environment. And remember
that this is taking place in real time. The second BGA is a dedicated
graphics engine. Again, consider how these games now look. Most are quite
close to reality, and some scenes would have you hard pressed to tell if you
were looking at a photo, or a piece of virtual reality. Given all that, just
imagine the billions of calculations that are going on, again in real time,
to work out the texturisation and surface rendering of all the visible
objects, and how the light and shadows interact with those objects as they
move within the scene. It really is mind-boggling just how sophisticated all
of this is now. I can recall 25 years ago when I worked on high-end graphics
systems, rendering the famous 3D conch shell image took a dedicated graphics
terminal, hosted by a VAX mainframe, around 20 minutes. That's one image,
not moving. Now think about a moving HD image in an HD background in real
time. That's a LOT of processing power, needing a lot of amps to perform ...

The fan on these things *is* large, as is the heatsinking assembly, and when
the processor finally decides to ramp the fan up, it sounds like a vacuum
cleaner. For this reason, at idle they tend to run it at below what I would
consider a 'sensible' minimum, exacerbating the thermal stresses on the
chips, their (lead-free) soldering, and the board to which they are
attached.

Arfa

==============================================================================
TOPIC: VCM driver
http://groups.google.com/group/sci.electronics.repair/t/59e08ffb8304f775?hl=en
==============================================================================

== 1 of 1 ==
Date: Tues, Aug 31 2010 7:28 pm
From: "stickyfox@gmail.com"

More info.. No takers so I took it apart. It looks like there's a high-
power op amp chip connected to a voice coil, but the mirror does not
seem to move easily in the mount. Maybe just rock back and forth by
the tiniest bit.

Anybody know what purpose it serves in a tv?

==============================================================================
TOPIC: Technics KN800 MIDI keyboard no sound
http://groups.google.com/group/sci.electronics.repair/t/f95dad92d98851fc?hl=en
==============================================================================

== 1 of 3 ==
Date: Tues, Aug 31 2010 7:34 pm
From: "stickyfox@gmail.com"

I've never seen the inside of a technics board, but I do frequently
see synths with a "protect relay" that keeps the amplifier isolated
until the digital circuitry has stabilized. They will click, but their
contacts get oxidized and don't transmit audio.

You can temporarily rejuvenate them by cycling them a few hundred
times (try connecting a function generator to the transistor that
drives it for a few seconds/minutes), but for the amount of work
involved I just replace them.

I've also seen volume controls open up. My usual approach is to strip
an RCA cord going to an amp, ground the shield, and connect a resistor
to the center pin, then poke around on the board listening for the
audio. Then I follow it until the sound goes away. If that doesn't get
me anywhere in 20 minutes or so I'll start looking in earnest for a
schematic.

On Aug 31, 7:06 pm, Geoff C <n...@mail.com> wrote:
> I was given a Technics SX-KN800 keyboard and am trying to repair it. I have
> opened it up and the six or so PCB's are easy to get at. The symptom is no
> audio. The PA thumps through the speakers on turn off and the PA has power
> supply OK so it is not a concern at the moment. The line out has no audio
> either. Of course it is possible that a crash has occured but I cannot find
> a reset so far. No audio is getting to the PA. I could not find any signal
> at the master volume either, though it may not have real signal at it.
>
> I believe it was made early to mid 90's. There are a lot of Technics
> proprietery chips in it. I have an op manual for a KN1000 which is similar,
> but no schematics appear anywhere I have seen.
>
> What I would like to know is a general question about how the audio signal
> is generated from the PCM pulse stream. It may be a simple LPF from a
> digital chip which regenerates the audio, or there may be a specialised
> audio chip to look for? If I can't go much further I will have to junk it.

== 2 of 3 ==
Date: Tues, Aug 31 2010 8:06 pm
From: Geoff C

"stickyfox@gmail.com" <stickyfox@gmail.com> wrote in
news:d3b060ed-09e5-4166-bf29-d6ee48becb4c@x25g2000yqj.googlegroups.com:

> I've never seen the inside of a technics board, but I do frequently
> see synths with a "protect relay" that keeps the amplifier isolated
> until the digital circuitry has stabilized. They will click, but their
> contacts get oxidized and don't transmit audio.
>
> You can temporarily rejuvenate them by cycling them a few hundred
> times (try connecting a function generator to the transistor that
> drives it for a few seconds/minutes), but for the amount of work
> involved I just replace them.
>
> I've also seen volume controls open up. My usual approach is to strip
> an RCA cord going to an amp, ground the shield, and connect a resistor
> to the center pin, then poke around on the board listening for the
> audio. Then I follow it until the sound goes away. If that doesn't get
> me anywhere in 20 minutes or so I'll start looking in earnest for a
> schematic.
>

I suppose the isolating relay would be on the power amp baord if it
existed, but I can't see it. I'll have another look for it though. I have
been using a scope for signal tracing, but your tracer idea has its
merits too, since it will be very quick.

Also, I have read the manual for the next model up which mentions a
method of resetting to factory defaults, and also a MIDI out only mode.
I'll try these too.

== 3 of 3 ==
Date: Tues, Aug 31 2010 9:33 pm
From: "William R. Walsh"

Hi!

> I suppose the isolating relay would be on the power amp baord if it
> existed, but I can't see it. I'll have another look for it though. I have
> been using a scope for signal tracing, but your tracer idea has its
> merits too, since it will be very quick.

Such a relay may not exist. If this thing's amplifier is anything like the
Technics stereo receivers from the same time frame, it may turn the output
on and off electronically. (An interesting aside: this electronic protection
method won't save your speakers if the amplifier itself fails!)

If you do find a relay, I'll practically guarantee it has burned contacts.
It seems that people didn't think about turning these off with a signal
still being amplified, which probably resulted in arcing at the relay
contact points. In all of my receivers that have one (an SA-929 and 560) the
protection relay can be opened without too much violence and the contacts
cleaned. I did break the magnet wire on the SA-560's relay, but that's
another story.

William

==============================================================================
TOPIC: LORAN C
http://groups.google.com/group/sci.electronics.repair/t/73c2d1e0342e191b?hl=en
==============================================================================

== 1 of 1 ==
Date: Tues, Aug 31 2010 11:13 pm
From: "Michael Kennedy"

This started out as a repair issue, my LORAN unit wasn't getting a signal. I
thought it was broken. I have been gone from the USA for 2 years and but
after some research I have found out that in my time gone that the
government has decided that we no longer need LORAN or any form of backup
for GPS.

I can only hope that we will see the LORAN system come back in some form in
the future. Is it just me or does it seem stupid to do away with out only
backup system for GPS?

LORAN is robust where as GPS seems qite frail in comparison. I have lost GPS
signals in bad weather but never LORAN, but maybe this is just my
observations and not a true representation of the facts.

==============================================================================
TOPIC: Technics SA-310 Receiver Fixed!
http://groups.google.com/group/sci.electronics.repair/t/266f00b3a43b6910?hl=en
==============================================================================

== 1 of 2 ==
Date: Wed, Sep 1 2010 12:27 am
From: "William R. Walsh"

Hello all...

Just thought I'd drop in and provide a quick status update. I learned a few
things along the way:

1. STK-2038 and 2038 II modules are not at all the same. Someone (not here)
told me they were electrically compatible with each other, and this is not
so. The STK-2038II has more pins and seems to be less commonly available.

A few people pointed me in various directions, and one pointed me to a new
old stock STK-2048 II module, still sealed in the factory wrapping. I opted
for that one; it's used in the next model up (the SA-410).

2. Nothing more than installing the new module was required. Everything is
playing great now.

3. I'll never push the unit *that* hard again (turned it up about halfway
and that was when it started to fold).

4. The internal protection circuit absolutely will NOT save your speakers if
anything goes wrong with the power amplifier. I was using an outboard
speaker protection device and it did the job when the hybrid module went the
rest of the way.

5. Computer Drive and its method of forcing the transistors in the hybrid to
remain turned on to some degree at all times seems to make them run really
HOT. Every SA-310 and 410 I've ever seen gets very hot, especially when
idling. I'm going to install a fan. The heatsink becomes ridiculously hot
within ten minutes of operation, so hot that it can't be touched. I don't
think this can be good for the hybrid.

I learned a lot and I appreciate everyone's help and commentary from this
group. I have no intention of finding out, but I do wonder what Computer
Drive actually *does* when the 60C temperature sensor attached to it
trips...? Honestly I'm surprised it hasn't--a 50C device is at least
touchable. This really isn't. And all the service manual says is that the
"Thermal" LED on the Computer Drive Monitor goes out when this happens.

William

== 2 of 2 ==
Date: Wed, Sep 1 2010 12:47 am
From: "N_Cook"

William R. Walsh <newsgroups1@idontwantjunqueemail.walshcomptech.com> wrote
in message news:yJGdnVZO5tv6nePRnZ2dnUVZ_sednZ2d@mchsi.com...
> Hello all...
>
> Just thought I'd drop in and provide a quick status update. I learned a
few
> things along the way:
>
> 1. STK-2038 and 2038 II modules are not at all the same. Someone (not
here)
> told me they were electrically compatible with each other, and this is not
> so. The STK-2038II has more pins and seems to be less commonly available.
>
> A few people pointed me in various directions, and one pointed me to a new
> old stock STK-2048 II module, still sealed in the factory wrapping. I
opted
> for that one; it's used in the next model up (the SA-410).
>
> 2. Nothing more than installing the new module was required. Everything is
> playing great now.
>
> 3. I'll never push the unit *that* hard again (turned it up about halfway
> and that was when it started to fold).
>
> 4. The internal protection circuit absolutely will NOT save your speakers
if
> anything goes wrong with the power amplifier. I was using an outboard
> speaker protection device and it did the job when the hybrid module went
the
> rest of the way.
>
> 5. Computer Drive and its method of forcing the transistors in the hybrid
to
> remain turned on to some degree at all times seems to make them run really
> HOT. Every SA-310 and 410 I've ever seen gets very hot, especially when
> idling. I'm going to install a fan. The heatsink becomes ridiculously hot
> within ten minutes of operation, so hot that it can't be touched. I don't
> think this can be good for the hybrid.
>
> I learned a lot and I appreciate everyone's help and commentary from this
> group. I have no intention of finding out, but I do wonder what Computer
> Drive actually *does* when the 60C temperature sensor attached to it
> trips...? Honestly I'm surprised it hasn't--a 50C device is at least
> touchable. This really isn't. And all the service manual says is that the
> "Thermal" LED on the Computer Drive Monitor goes out when this happens.
>
> William
>
>

If the "outboard speaker protection device " is a "crowbar" how do you know
it was not a failure in that which knocked out the amp ?

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