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Yamaha CR-220 sound dies after a few seconds of sound - Please Help!

I have the same issue. My one did not make any sound and I found some cracked soldering so I soldered them. Sound comes out for a few seconds and stops. This happens whenever I power on.
 
Do you get audio through headphones?
Assume both channels affected.
Do you have a multimeter/comfortable taking voltage measurements?
 
Yes, headphones make same sound with speakers. Each channel last differently. Sometimes one channel last longer than the other with noise. Yes, I do have a multimeter and oscilloscope. I will check the voltage that W.T.Holt checked tomorrow.
 
My voltage on J109 is funny. It starts from around 10V when I power on. Then it increases slowly to 27V over 10 seconds. When it goes over 25V, a little sound starts coming out with noise.

One strange thing on L1/L2/L3/L4 is that they are 42V/42V/42V/0V. 14V bulbs are connected there so this voltage is out of its spec.
 
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audiojung said:
One strange thing on L1/L2/L3/L4 is that they are 42V/42V/42V/0V. 14V bulbs are connected there so this voltage is out of its spec.
Click to expand...
Finding that odd. Measuring Vdc, black probe connected to chassis/GND? Should blow the bulbs, are they working?
Is R802(?) 270ohw/2W series resistor in spec?

With both channels affected it's wise to check out the power supply 27Vdc for J109 is ok, though a little slow to get there.
Check Voltage at J105, expect +25Vdc
Repeat for J104, expect -25Vdc

upload_2020-5-23_18-43-7.png
 
Also need to check out TR713. Measure Vdc at R761 one side. Repeat for other side.
Need TR713 emitter Vdc.
upload_2020-5-23_18-57-58.png
 
The voltage seems very wrong. I worried that some elements are burned out.
J104 -3V
J105 48V

R761 ( left -2.2V right -2.8V )
E of TR713 -1.5V
 
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I went a little upstream and I found that TR801 has wrong voltage too.
TR801
E 27.2V ( Should be 30.9V )
B 27.8V ( Should be 31.4V )
C 41.8V ( correct )

TR803
C 22V ( Should be 41.5V )

Visually nothing is wrong but I wonder if I need to replace capacitors around TR801~803.
 
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audiojung said:
I went a little upstream and I found that TR801 has wrong voltage too.
TR801
E 27.2V ( Should be 30.9V )
B 27.8V ( Should be 31.4V )
C 41.8V ( correct )
Click to expand...
Probably close enough -- not and issue..
 
Yes, both lamps are out. Okay, I wouldn't worry about them. Then this is the only one that is off too much.

TR803
C 22V ( Should be 41.5V )
 
What DC voltage are you seeing at the collectors of the 4 output transistors ? TR719,720,721 and 722 ? Looking for +/- 25 vdc ballpark.
 
R808 : I checked it when it is on the board and it is 380Ω. It seems good.
C815 : I took this out and it was 25µf instead of 47. I replaced it with a new one. Fortunately I had one.

However, it did not improve. C803 has still 22V on C.

I looked for TR719~722 but they don't show up in my manual. I assume that they are four on top of the circuit boards. I don't know which one is C but none of it has 23V. There are a couple of 46V so the input voltage must be wrong there too.
 
They will look like this...
2sc2073-pinout.jpg
Center pin and the metal tab are the collector of this style transistor.
 
Caution don't short the center pin to either of the other pins. Or you will destroy the transistor.
 
Yes they are -3V 46V -3V 46V from left to right when I look at from bottom. Ground in the chassis and measuring with red one.
 
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