Yamaha CA 600 Repair 2026

[avionic]

What I am understanding here is I need to set Bias before mid point voltage or is it visa versa?

Doesn't really matter.

 

[PioneerPro]

MBZ - In regards to your requests. Check orientation of TR601 and TR603 YES, both Emitters are touching on the same track, so they are installed correct.

Resistance at both fuse bottom clips with no fuses in. I am guessing the amp needs to be ON the DBT and ON. Both readings start low them stabilize at about 5.40 ohms.

I 100% did not damage the mica insulators. I removed these transistor only to test them with a MM.

Resistance of FR601 - Starts low and goes up, stabilizes at about 17.5 ohms. If I reverse the MM probes it goes to OL. This is in the board and not desoldered.

Measure to One Decimal Place. Now sure what that means and my MM does not have a setting for that but I have other MM's.
VDC at TR605 Blue = 7.6
VDC at R617 Yellow = 9.17
VDC at Ceramic Cap = 21.0

 

[PioneerPro]

Doesn't really matter.

Are you sure, because in my 12th message I said, I can manipulate VR601 by Changing VR602

 

[Nashou66]

MBZ - In regards to your requests. Check orientation of TR601 and TR603 YES, both Emitters are touching on the same track, so they are installed correct.

Resistance at both fuse bottom clips with no fuses in. I am guessing the amp needs to be ON the DBT and ON. Both readings start low them stabilize at about 5.40 ohms.

I 100% did not damage the mica insulators. I removed these transistor only to test them with a MM.

Resistance of FR601 - Starts low and goes up, stabilizes at about 17.5 ohms. If I reverse the MM probes it goes to OL. This is in the board and not desoldered.

Measure to One Decimal Place. Now sure what that means and my MM does not have a setting for that but I have other MM's.
VDC at TR605 Blue = 7.6
VDC at R617 Yellow = 9.17
VDC at Ceramic Cap = 21.0

Never take ohm reading with power on.

Redo with power off.

Hopefully your meter wasn't damaged

Athanasios

 

[avionic]

I can manipulate VR601 by Changing VR602

There is another issue then.

Yamaha service manual adjusts the DC offset(mid-point) prior to adjusting the idle current(bias). If DC offset adjustment is available.

 

[PioneerPro]

Never take ohm reading with power on.

Redid with the power off and got the same 5.3 to 5.4 ohm readings at the bottom of the fuse holders.

Redid the ceramic resistor with the power off and got 17.5 ohm then I reversed the probes and got 11.1 ohms.

There is another issue then.

Yamaha service manual adjusts the DC offset(mid-point) prior to adjusting the idle current(bias). If DC offset adjustment is available.

Yes, as I stated in post #12 I tried to do the DC offset and turning the VR601 trimmer did nothing on the meter at all.




Have We Decided If The Can Transistors I Replaced Was A Good Move Or Not?

Again - Thanks for all the help guys.