• The move to the new server is done. There are some software and database maintenance updates in process. This has us passing the hat around to help out. We appreciate any donations. Seriously, even a dollar helps. The payment page may be found here - https://www.audiokarma.org/support.html

Yamaha CR-600 restoration advice

Have you already replaced the electrolytic caps? C814 - 816?
 
avionic said:
Have you already replaced the electrolytic caps? C814 - 816?
Click to expand...
Yes. Correct orientation on all of them, resistance looks fine between terminals. Is it safe to take it off the dim bulb for that zener? The highest voltage I’m seeing at the main board pots is -12V for VR702 so I’m worried something’s gonna give way
I just checked the cathode of D806 on the dim bulb, reading 15.7V
 
Last edited:
Without speakers attached. Disconnect the pre-amp from the power amps with the rear panel coupler switch. Power up with the dim bulb. How does the dim bulb react?
 
avionic said:
Without speakers attached. Disconnect the pre-amp from the power amps with the rear panel coupler switch. Power up with the dim bulb. How does the dim bulb react?
Click to expand...
Coupler switch flipped to on position, no difference in the dim bulb. Just to be clear, that 15.7V from the zener while on the dim bulb doesn't bode well?
 
Joolian said:
Coupler switch flipped to on position, no difference in the dim bulb. Just to be clear, that 15.7V from the zener while on the dim bulb doesn't bode well?
Click to expand...
No it doesn't. I'd measure it without the dim bulb. With mini-grabber test probes. Or.. You can just replace the diode with a new one.
 
Joolian said:
Without dim bulb, I'm getting 32.9V. I'll get that new zener ordered
Click to expand...
You don't need it. That zener is working. I think the dim bulb has been forking with you the whole time. What voltage do you have at the emitter of TR802 without the bulb?
 
Time for and audio test. After resetting the bias/idle current while on the straight mains voltage. No bulb.
 
avionic said:
Time for and audio test. After resetting the bias/idle current while on the straight mains voltage. No bulb.
Click to expand...
About that.. transformer voltages look good, +12, +12M, +12R, +30 all look good, +/- BR sitting at their respective 39V, but +/- BL giving me 400mV on the positive side and nothing on the negative. Right channel offset stuck at rail voltage. Left channel offset stuck at 78mV. 0V on either channel’s bias.
Edit: voltage is normal on the inside end of left channel fuses (circled), but both fuses are blown. I don't know if this is something that happened today but I've checked them a handful of times prior and they were intact. Will grab some more from the store tomorrow.
1777685754784.png
 
Last edited:
Joolian said:
but both fuses are blown
Click to expand...
Left channel amplifier rails.

What all has been done to the left channel power amplifier?

Measure the resistance between the output transistor (case) collectors and chassis ground. Without power of course.
 
avionic said:
Left channel amplifier rails.

What all has been done to the left channel power amplifier?

Measure the resistance between the output transistor (case) collectors and chassis ground. Without power of course.
Click to expand...
Both channels have been recapped. Left channel on continuity mode between collectors and chassis are reading in the hundreds of mV range while right channel is sitting cleanly 0L
 
Joolian said:
Both channels have been recapped. Left channel on continuity mode between collectors and chassis are reading in the hundreds of mV range while right channel is sitting cleanly 0L
Click to expand...

He asked for resistance, not voltage . With power off . ;)
 
You must log in or register to reply here.
Back
Top Bottom