(Dave Platt) wrote in
:

snip

Thank for replying.

Well, I'd say that one of the two standard approaches would
work. Which one you would use, depends on what sort of test
equipment you have available.

Two gator clips with a flashlight bulb and 1.5 V battery, and a
$5 voltmeter.

Probably the easiest approach is "work backwards". You'd

snip

Please see the huge update for details, including a CRUCIAL one!

Take all of the appropriate safety precautions, of course!

snip

if I recall correctly, some
turntables have anti-thump muting switches which short
the signal from the cartridge until the stylus is
playing the groove),

I do not believe this unit has this. It worked before - as you
will read (if you dare enter!) in the update below...

or

- Dried out and "open" electrolytic capacitors, coupling
one stage

Everything works, and looks clean and almost new. I can not id
WHERE the phono preamp parts actually are, but IT WORKED BEFORE
(see update below).

-- Update (very long, I apologize!) --

First of all, many thanks to all who replied. It is very much
appreciated.

Now for the /bad/ part.

Something one person mentioned in his reply made me remember a
rather *crucial* detail which I had forgotten (I am not
completely senile yet, but I have been /incredibly/ busy for the
last few weeks, and my brain is running out of RAM).

It is this: BEFORE I removed the BSR turntable, I DID check to
see whether there was AUDIO SIGNAL coming from it. There was,
loud and clear - when I touched the stylus, it sounded like an
earthquake. Very little "system noise", too.

The turntable itself was "seized" - after I have (with some
violence) managed to take it apart, I saw that the 2 main cog
wheels of the belt-less motor were practically frozen together
at a bizarre angle and would NOT budge. I have NO idea how that
happened - and the 4" screwdriver shaft, 2 children's plastic
letters with magnets, and assorted bits of 30+ year old food I
found inside the receiver could NOT have had anything to do with
it, either, since the BSR motor was fairly well enclosed within
the /incredibly/ complicated mechanical design (a changer).

Now that I have remembered this, it is obvious I screwed
something up. I have never seen a ceramic cartridge, but I am
99.99% positive that BOTH the BSR and the Sony (ca. 1990)
turntable carts are magnetic. So, since I have no signal but
weird pink noise, I must have screwed up the cables. Or do you
think I may have destroyed the preamp?

(This may be a good moment to mention that I am using the term
"phono preamp" in a generic sense. I always thought a phono
preamp might be/would be a small enclosed piece of electronics,
but in this receiver, it appears to be a part of the main
circuit board - the two original (and now extended) cables from
the BSR turntable stylus/arm are soldered right onto the circuit
board, and go who-knows-where - presumably, into components
which make up this receiver's "phone preamp" section.)

(THIS may /also/ be a good moment to mention that while I have
had some disastrous luck with simple things and astoundingly
good luck with complicated things, I am NOT a technician, and do
not own an oscilloscope - I check connections with two gator
clips connected to a 1.5V battery with a flashlight bulb, and
after over 30 years of "considering it", I finally bought a five
dollar "voltmeter" which /appears/ to work - I found out a cheap
110V/22V AC/DC adapter outputs 25VDC when set to 12V output
[when the input voltage is set to 110V] and 12.5VDC from its 9V
setting [when the input voltage is set to 110V (it is 110V
here)]. The Sony turntable (originally a component of a system,
with a tiny power connector which plugs into the back of the
main system unit and where I found out 12VDC is output) is
running on a supposedly "regulated" fancy Radio Shack AC/DC
adapter which puts out 11.8V DC. (When I reverse the polarity,
the turntable spins backwards.)

If anyone has read this far, please accept my deep thanks for
your patience. I can't write more concisely - I realize it's an
illness.

Anyway - the question now is WHAT did I do to mess things up?
Since I consider the receiver largely indestructible, I do not
think I have *destroyed* anything, not to mention the voltages
involved are totally minuscule and it being a solid state unit -
as the front panel proudly states ;-) - there is little danger
of blowing it up. Plus everything else works.

My plan is as follows:

1. Cut the original "BSR cartridge/turntable to the main circuit
board" cables, strip ends.
2. Attach gator clips to them and connect to the Sony turntable
output cable.
3. Hopefully, hear sound. Extend cables again, making SURE I
don't screw up this time.

If I hear no sound, I will connect the 4 very thin cables from
the original BSR cartridge (I saved the cart assembly and cables
before I saw the turntable was connected to the circuit board
with 2 standard cables with RCA plugs) to the cut cables leading
to the circuit board and see if I hear anything. If I do, I will
post for more advice.

But for now, my question is:

If after doing all this, I still get the /same/ pink noise (NOT
hum - strange, huh?) and get NO audio, WHAT do I do?

Thank you /very much/ for your patience, and my apologies for
having forgotten a crucial part of the puzzle. Further help will
be greatly appreciated. If anyone wants to see pix of the 2
cartridges or the circuit board where the phono audio cables are
soldered into it, I can post them to photobucket or something,
OR a binary group if you have binaries access.

The replies are different in every one of the 5 groups, so I
will post this followup to each group separately. I don't really
understand how crossposting works, since I never do it, and
eternal september /may/ be "funny" about crossposting to boot.



--
Any mental activity is easy if it need not be subjected to
reality.