Yamaha CR-2020 in and out of protection

HyKlas

Super Member
Figured I'd give it a shot before biting the bullet and taking it in..

This only happens after it's good and warm, and only with speaker load attached. Headphones alone will not trigger the issue, or so it seems from my testing.

The unit will go in to protection for a brief period, possibly 2-4sec, then return to normal operation for a time. This will repeat at random intervals.

Checked DC offset and removed it from the case. This is as far as I've gotten. Left channel offset is 9mV and right channel is 12mV.

Is there something in particular I should be looking for? Limited on tools but I do have quite a few high quality multimeters with many types of leads so I can check multiple voltages at any given time.

I'm finding myself wanting a pair of dummy loads for this as I can't get it to happen as much at low volume. Or again, so it seems.

Any help is greatly appreciated as I'm trying to move some equipment out and need this for the would-be hole in the bedroom system. Thanks in advance all!
 
The unit will go in to protection for a brief period, possibly 2-4sec, then return to normal operation for a time.

At any volume level ? What impedance are the speakers ?

Do you know if the service bulletins for this unit been done yet?
 
I can't get it to happen as much at low volume
Possibly your just pushing it to hard and its running out of gas and clipping.
 
No service bulletins have been completed as far as I can tell. The previous owner wasn't aware of them being completed either.

Will do it at any volume. Most of the time it is below 2 and hardly breeches 3 on the dial. Now keep in mind it's a 15x15 bedroom running a pair of HPM-100 so 3 is quite loud.
 
No service bulletins have been completed as far as I can tell. The previous owner wasn't aware of them being completed either.

Will do it at any volume. Most of the time it is below 2 and hardly breeches 3 on the dial. Now keep in mind it's a 15x15 bedroom running a pair of HPM-100 so 3 is quite loud.

Humm. Could be a few different issues.Like cold solder connections on the PS board.

Put the volume control at say 1 on the dial and wiggle the relay to see if you can make it act up or... pull the board loose and have a look see at the soldered connections underneath.Specially on the TO-220 pass transistors(they have little square aluminum heatsinks fastened to them.)
 
Looks like I'm reflowing TR712, TR715, and the relay... Guess I didn't wiggle them enough when I was poking around last night. TR712 and the relay definitely cause it to act up but I'll hit TR715 as well. Thanks much! Time to bust out my bulletin sheets it seems...
 
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Looks like I'm reflowing TR712, TR715, and the relay... Guess I didn't wiggle them enough when I was poking around last night. TR712 and the relay definitely cause it to act up but I'll hit TR715 as well. Thanks much! Time to bust out my bulletin sheets it seems...

Bulletins should be done sooner rather than later.:thmbsp:
 
Good thing i pulled it apart too... Pressed on R802 to check the joint and the solder broke. Board is black in that area as well.

I'm having trouble finding a pair of 2SD525 transistors but the 33-Ohm and 22-Ohm resistors are on their way.
 
Good thing i pulled it apart too... Pressed on R802 to check the joint and the solder broke. Board is black in that area as well.

I'm having trouble finding a pair of 2SD525 transistors but the 33-Ohm and 22-Ohm resistors are on their way.

Use a TIP41C . The 2SD525 are no longer available. If you did find a 525 it is most likely counterfeit.
 
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Looks as though I should have just taken it in. Most of the trace pads have come off completely. I wouldn't have the slightest idea, let alone the hand, to fix that. Discouraging..
 
Welcome to the 2020, those boards FRY, literally. I don't think there isn't a 2020 on the planet that was used that doesn't have this issue.
 
To much iron heat for to long. To repair you can point to point wire the solder side of the PCboard.
 
To much iron heat for to long. To repair you can point to point wire the solder side of the PCboard.

Yea, I took lots of pictures of my CR2020 restoration. But I never took a picture of my point to point wiring on the back side of that toasty PS board! It was ugly! But it functions beautifully. What a nice receiver.:yes:
 
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