• 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-620 Protection Relay Fun

JB8 said:
My first reporting on FR801 is a mystery, not sure how I could have possibly gotten any reading since I honestly can't confirm where the part lives on the circuit board... apologies. Sounds like only the E and G versions have these (?), but it may be right in front of my face, perhaps you can direct me to where this FR should be?
Click to expand...
TR802 voltages
E -- .14 vdc
C -- ?
B -- ?
 
JB8 said:
My first reporting on FR801 is a mystery, not sure how I could have possibly gotten any reading since I honestly can't confirm where the part lives on the circuit board... apologies. Sounds like only the E and G versions have these (?), but it may be right in front of my face, perhaps you can direct me to where this FR should be?
Click to expand...
US model has a jumper wire... So disreguard..
 
Wow! Such great detective work, I knew you'd sniff out the culprit! Check out this pic...

IMG_1303.jpg

When I first did a cursory inspection of the caps, etc, this was not only hidden in a shadow, but there was also that mass of adhesive around the base of C802, partially obscuring what looks like my first exploded zener. I've never seen this before, should have looked with more light and better magnification.

I need to order a grip of the 30 volt 500ma (?) zener diodes and I'll update this thread once this guy has been replaced. If anyone has a favorite here, or a part number, or the wattage, I'll take it! (Ha, Avionic beat me to it, thank you!)

After the new zener is installed is there anything else I should check before firing up the unit or do these just occasionally blow and need to be replaced? Would hate to install a new one only to have it blow as well.

Thank you all, as always, for the assistance, much appreciated!
 
Last edited:
I've already removed both, C803 was fine, 1113 uF, intact at the base with no leakage, ESR was .38. The zener, in contrast, came out in two pieces and there was a burnt area beneath it. Zener has been ordered based on your recommendation.

Thanks again, have a great evening! :thumbsup:
 
1000uF for C802, 100uF for C803. C802 was the part I was referring to, my mistake.

Both have been pulled and checked. C802 tested at 1113uF and C803 at 122uF. I'll likely just replace both even though they're not wildly out of spec. I'm always surprised at how the capacitors in Yamaha's from this era are consistently less out of spec than most other brands from the same timeframe.
 
Update and Questions:
  • D802 replaced along with C802 and C803 - I went with the Zener you suggested, Avionic, went with factory values for C802, bumped the voltage value only on C803, to 63V
  • Relay still kicks in quicker than all other CR units I've worked on - it kicks in right after the power button has been pushed, most others I have kick in after roughly 2-3 seconds - Is this normal?
  • Fired it up through DBT, lights up (flashes) quickly, relay clicks in, DBT goes dark, but with speaker A engaged I can see a tiny bit of light and if I crank up the volume the bulb (60 watt) brightness increases - Is this normal?
Btw, R801 checked out fine, thanks, @ecluser for the heads-up.
 
JB8 said:
it kicks in right after the power button has been pushed, most others I have kick in after roughly 2-3 seconds - Is this normal?
Click to expand...
No..
JB8 said:
Fired it up through DBT, lights up (flashes) quickly, relay clicks in, DBT goes dark, but with speaker A engaged I can see a tiny bit of light and if I crank up the volume the bulb (60 watt) brightness increases - Is this normal?
Click to expand...
Remove the DBT.. Set the idle current.. Check the DC offset.
 
  • Like
Reactions: JB8
JB8 said:
- it kicks in right after the power button has been pushed, most others I have kick in after roughly 2-3 seconds - Is this normal?
Click to expand...
Replace C816 33µf/16vdc ...Little violet colored one right next to TR808.. If you haven't already..
 
Thank you. I'd already replaced C816, so it should be fine.

Idle current was just under 8 mV on left channel, around 14 mV on the right, so I adjusted it to 8 mV.

DC at the speaker terminals started at around 260 mV then steadily retreated, this was on both channels. I didn't wait it out to see either channel bottom out, both slowed considerably but continued to drop in voltage very slowly once they were lower than 50 mV. If there's a preferred way to check the DC offset please let me know, eager to learn the proper procedure.
 
TR809 could be shorted E to C.. TR808 could be shorted...Or you have bridged solder connections..
 
Upon further inspection I installed the incorrect transistor at TR808 (thought I'd installed an KSC1845 but it was a KSA922 o_O), and since the problem was never TR808 or 809 and instead D802, I reinstalled the original transistors and all is working as it should. Getting that 3-4 second delay for the relay, I think I'm in good shape now. Also getting roughly 30 mV on the left speaker terminal, 12 mV on the right.

Thanks again for always keeping me honest and on task. I'm learning more and more with every unit. You don't mess around and I respect your approach, much appreciated!
 
You must log in or register to reply here.
Back
Top Bottom