• Please note that Audiokarma will be offline briefly for updates early on Monday morning, September 28th.

New to me 610II - Distortion

Post a good clear photo of the two pair of test points 1,2,3 and 4... on the circuit board.
 
yes, thin film on both sides.
The 2 resistors that go with the 2 transistors that were missing when I got it were shot...they ceramic was actually cracked. I removed and replaced those. Ill check the other two.
Incorrectly marked?
 
ok...cant seem to upload from my phone...Ill try once I can get to my computer.
I can provide a video however...
 
I have to be able to read whats printed on the circuit board..Clear up close photo of the test points. I need to see how they are labeled.
 
Last edited:
Kapco said:
Incorrectly marked?
Click to expand...
Yes. Test points may be incorrectly marked. Yamaha has a lot of misprints and errors in the service manual and circuit board silkscreening.

Possibly why you couldn't adjust the bias. Service manual was guiding you to the wrong test points.
 
Last edited:
Use TP1 and TP3 for one channel --->adjust VR481
Use TP2 and TP4 for the other channel ---> adjust VR482

Like I said earlier. With a digital multimeter. The probe polarity is not important.

If the neg (-) sign bugs you. Swap the test probes around.
 
Last edited:
What voltages are you reading on the output transistors collectors ? ( metal case)

Should be + and - 42 vdc ballpark.
 
That's what I assumed...but didn't want to release any smoke.
So..TR 502 & TR501( the MJ21196) are 43v
I got 0.3 on the TR503&TR504 (MJ21195)

Appreciate the help. I'm wondering if one of these white resistor fuses??? May be no good. Do these "blow" if overdrawn on the amperage they have written on them?
 
Last edited:
avionic said:
Your missing the negative rail. Those two large caps are back by the transformer aren't they ? One could have vented.

Yes....I thought they were good...when I tested them the best I could the reacted like a cap should....started "charging up" from the meter. The rail outputs of the transformer both have ac voltage coming off relative to ground.


Which one and what did you replace it with ?
Click to expand...
Replaced it with a NTE 5329 which is a 200v/6A bridge rectifier.

I'll see if I can trace back what's going on...I was just thinking of checking voltage at the caps to ground when you responded. I assumed if a cap was toast would have blown the fuse....I guess maybe it could go open.
 
OK....checked the bridge in operation...I got both +&- 44v on the outputs . checked the big caps in operation....the negative rail has 0v at the cap
 
OK...strange....on the negative post of one cap I got the 44v. On the positive post of the other I got 44v. Just need to figure out which cap is which
 
Also look over the solder side of the board in the vacinity of the power supply caps,rectifier for burnt open copper traces or poor solder connections.
 
Turned it off. Checked caps again. The one with voltage at the negative post to ground holds 44v. Tgr cap with 44v at the positive post lost its charge quick
 
Kapco said:
OK...strange....on the negative post of one cap I got the 44v. On the positive post of the other I got 44v. Just need to figure out which cap is which
Click to expand...
Look at the schematic. Note the polarity marks on the large caps. Pos ---------- Neg,Pos ---------- Neg
 
You must log in or register to reply here.
Back
Top Bottom