CR-1000 humming from both channels

With CR powered off/unplugged, put black probe in AUX1-Left RCA, red probe at white wire, brown wrap tone board. Input selector
set to AUX-1, measure resistance.

Repeat for AUX1-Right RCA and red wire brown wrap.

The resistances should be about the same +/-20%
These go down to 0 ohms
 
I don't see this taking out the right channel...

Measure dc voltage, red probe, black? wire(earth) brown wrap on tone board, black probe on chassis, expect 0mV +/-
Measure dc voltage, red probe, red wire, white wrap (in red wrap?) on loudness board, "ri", black probe chassis. Which
is higher voltage (red wire on loudness or tone board)
I don't see this taking out the right channel...

Measure dc voltage, red probe, black? wire(earth) brown wrap on tone board, black probe on chassis, expect 0mV +/-
Measure dc voltage, red probe, red wire, white wrap (in red wrap?) on loudness board, "ri", black probe chassis. Which
is higher voltage (red wire on loudness or tone board)
 

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These go down to 0 ohms
I bet that surprised a few people, myself included.

I appreciate your work on the voltage measurements however a few mV is not going to point
to your problem of a failed right channel. It will present as either background hiss or hum which
would be improved by the replacement of the remaining 2SC1345 TR's. I did not see the 100mV
which interested me a little.

At this stage the voltages indicate nothing of interest so this line is a dead end.

For this problem, the ideal tools are an oscilloscope. Assuming you don't have one. An alternative
would be a signal generator to generate a sine wave that your multimeter will be able to detect
as an AC voltage. There is freeware on the net that uses your pc soundcard to act as a signal
generator (also as a cro for that matter). Alternatively again, you can find someone with an
oscilloscope.
 
The receiver will go to a repair shop.
I had a similar problem with my other CR-1000, no right channel. The techs then told me that the reason was dirty switches and sliders. This time I fitted in all the stuff that did not require soldering from the working unit, only loudness and balance sliders were not transplanted, I tried to clean them though with deoxit. Still no change.
 
I should clarify that the RCA-tone board resistance test covers
the function, tape monitor and mode switches and the balance
and volume.

It does not cover the loudness slider, this can be tested by
resistance measurement black probe, red wire orange wrap on
loudness board, red probe, red wire yellow wrap loudness board
(ie, measure from RI to RO with slider in middle position).
Repeat for white wires (LI, LO). Expect about the same +/-20%
No reading/open circuit indicates a problem.
 
I should clarify that the RCA-tone board resistance test covers
the function, tape monitor and mode switches and the balance
and volume.

It does not cover the loudness slider, this can be tested by
resistance measurement black probe, red wire orange wrap on
loudness board, red probe, red wire yellow wrap loudness board
(ie, measure from RI to RO with slider in middle position).
Repeat for white wires (LI, LO). Expect about the same +/-20%
No reading/open circuit indicates a problem.
thx, will test it.
 
With CR powered off/unplugged, put black probe in AUX1-Left RCA, red probe at white wire, brown wrap tone board. Input selector
set to AUX-1, measure resistance.

Repeat for AUX1-Right RCA and red wire brown wrap.

The resistances should be about the same +/-20%
I did it wrong last time, but still seems ok I guess
for left channel 2.3kOhms
for right channel 2.5kOhms

both very close to 1kOhms at max volume
 
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I should clarify that the RCA-tone board resistance test covers
the function, tape monitor and mode switches and the balance
and volume.

It does not cover the loudness slider, this can be tested by
resistance measurement black probe, red wire orange wrap on
loudness board, red probe, red wire yellow wrap loudness board
(ie, measure from RI to RO with slider in middle position).
Repeat for white wires (LI, LO). Expect about the same +/-20%
No reading/open circuit indicates a problem.
left 6.75kOhms
right 7.00kOhms
 
The resistance results don't indicate a switch contact problem as both channels are attenuated
by about the same amount. The volume/balance/sliders can have differences of upto 20 percent
between L&R channels, so results are ok.

To proceed further you need either a signal generator or an oscilloscope.

There is free software, which I've already suggested but nobody interested, see thread
http://audiokarma.org/forums/index....ight-channel-in-vintage-yamaha-ca-610.751622/

If you know a cheap reliable tech then pass it onto him, however if you want to learn a little...
 
The resistance results don't indicate a switch contact problem as both channels are attenuated
by about the same amount. The volume/balance/sliders can have differences of upto 20 percent
between L&R channels, so results are ok.

To proceed further you need either a signal generator or an oscilloscope.

There is free software, which I've already suggested but nobody interested, see thread
http://audiokarma.org/forums/index....ight-channel-in-vintage-yamaha-ca-610.751622/

If you know a cheap reliable tech then pass it onto him, however if you want to learn a little...
Yeah. I have the software but how to use it now?
 
run the install etc... once done double click the
"scope" application. Just hit continue, no license.

SIGNAL GENERATOR
top middle tab signal generator

Top left corner Aplitude CH1 100mV is plenty

Frequency 1000

Push Channel 1 green button

You will need a 3.5mm to RCA cable as you might use to
connect an ipod or other to your amp. Connect this to your
line out of your PC

However, as you've come this far, I suggest you try the
oscilloscope. Next post. Capture27.JPG
 
OSCILLOSCOPE
You will need to make up a probe, this can be just
about anything you can connect to a 3.5mm plug.
eg, old multimeter probe or just a clip...

Connects to your LINE-IN on your pc.

Do not attempt to measure high voltages (>5V???)
this will damage your soundcard.

2 Channels RED and GREEN trace

Adjust voltage range/scale (like a multimeter), stick
with 100mV but adjust as necessary

Adjust Time resolution as necessary

Plug in probe, nothing else required

Capture28.JPG
 
OSCILLOSCOPE
You will need to make up a probe, this can be just
about anything you can connect to a 3.5mm plug.
eg, old multimeter probe or just a clip...

Connects to your LINE-IN on your pc.

Do not attempt to measure high voltages (>5V???)
this will damage your soundcard.

2 Channels RED and GREEN trace

Adjust voltage range/scale (like a multimeter), stick
with 100mV but adjust as necessary

Adjust Time resolution as necessary

Plug in probe, nothing else required

View attachment 901781
I will buy a usb oscilloscope and will come back to it. Maybe using the software just for generating signal.
 
I have the right channel back. A bit crackling when I use volume pot or balance slider. So dirty controllers have been the reason I guess? I am cleaning them but no progress...
I just turned the receiver on and the channel was back. Maybe the deoxit was doing its work for some time. I was always not very lucky with cleaning pots. Once I used 2 cans, 1 D5 and 1 F5 and nothing. I sent it to techs. I later asked them, how they did it. They said, proper chemical spray, compressed air, chemicals again, air, greasing and has to work. This is exactly as I do it myself...
The rubber curtain at balance slider melts when treated with contact cleaners containing solvents :( , well at least gives out the black colour.
 
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