CA-1010 Unable to adjust Class A bias, Normal OK

[Yamaha5000]

Would be good to have the yamaha spec for the diode so can better tailor, candidates are,
View attachment 2531578

Since it's a switch function it probably doesn't need to be super accurate. Since
the NZX20C-133 worked in the CA-2010 then ok for the CA-1010. My initial choice was
Mouser 771-NZX22A,133 21.4V 2% 500mW
EDIT: Zener voltage is not super critical, the zener acts like a switch. In AB the +B rail is at about +55V and the B1 rail at about +65V so the zener doesn't conduct so TR315 remains off with TR312 off. TR311 is on so bypassing VR302. In class A +B rail is about +22V so there is >21V across the zener so current flow from TR315e turns on TR312 which disables TR311 so VR302 is "in play"

Ordered from Mouser today, should be here tomorrow.
I also found that TR315 had failed

 

[Yamaha5000]

Nashou

I have stated many times that I am very appreciative of all constructive input. I want to take a moment to thank everyone who has contributed to help me solve problems,

I have tried very hard to understand what information I have received and also reply to any request for further explanation and test results as requested. When I state something and you find it confusing please request a further explanation. I would much rather receive a request for information (RFI) than to receive silence. As I have traveled this journey on AK I have tried to learn how to ask questions properly and feel that I have made great forward strides.

Once again thank you for your assistance.

 

[Yamaha5000]

Installed WZ210, now bias on Normal and Class A are setting at 570mv and neither VR301 or VR302 have any effect.

 

[mbz]

Installed WZ210, now bias on Normal and Class A are setting at 570mv and neither VR301 or VR302 have any effect.

TR315 was faulty, replaced, correct orientation?
Possible issue with TR311,2. Would need TR311,2,5 b/c/e voltages to GND. You should reset both VR's to minimum (CCW) before attempting to set bias.

 

[Yamaha5000]

TR315 was faulty, replaced, correct orientation?
Possible issue with TR311,2. Would need TR311,2,5 b/c/e voltages to GND. You should reset both VR's to minimum (CCW) before attempting to set bias.

Thank you. I will do your recommendations in a couple hours. TR315 was faulty, replaced, oriented correctly (per Yamaha silkscreen)

 

[Yamaha5000]

TR315 was faulty, replaced, correct orientation?
Possible issue with TR311,2. Would need TR311,2,5 b/c/e voltages to GND. You should reset both VR's to minimum (CCW) before attempting to set bias.

This has become much more complex in one fell swoop.
I need to back off of this and try again tomorrow with a more clear mind.

 

[Yamaha5000]

TR311,2,5 b/c/e voltages to GND.

Just to clarify:

TR311
TR302 ?
TR305 ?

 

[mbz]

Just to clarify:

TR311
TR302 ?
TR305 ?

TR311, TR312, TR315

 

[Yamaha5000]

2SA745 Failed
After taking these in and out of the heatsink one of the MICA insulators developed a crack

I see on AK as replacements
2SA745 - MJ21193
2SC1403 MJ21194

I see on AK that the CA-610 uses these same transistors, I just so happened to buy a CA-610 yesterday as a parts unit.

https://audiokarma.org/forums/index.php?members/clinic-audio.119442/ has the originals, but getting him to quote is nearly impossible if not impossible, then shipping is a mountain that can not climbed.

 

[mbz]

The ON-SEMI MJ's are fine, higher Ic, Ib, Vce... specs than the OEM. Use the CA-610 as a learning exercise and try and repair.

 

[Yamaha5000]

Do you recognize?

 

[Yamaha5000]

View attachment 2533719

Do you recognize?

 

[mbz]

10DC common anode or cathode diode pair, used as rectifier, don't recall those being in the CA-1010.
Use MUR1620CTG/MUR1620CTRG as replacements, need to diode test to work out if it's common anode (10DC-2R) or cathode (10DC-2) or is it 10DC-1... Vaguely recall one was black and the other was red...

 

[Yamaha5000]

Labeled as a 14D

 

[Yamaha5000]

It is a common cathode
Doesn't have a complementary common anode as the 10D set

 

[mbz]

Labeled as a 14D

Possibly manufactering information (location, date,,,) Used in CA-800 and CA-1000 and ...

It is a common cathode
Doesn't have a complementary common anode as the 10D set

A complementary part will almost certainly exist however it may not be needed/used in your application, eg, half wave...

Taken from what amp?

 

[Yamaha5000]

Just messing around with a Yamaha Tuner while waiting on CA-1010 parts from Mouser

Photo shows this to be a 14D, parts list and schematic show this to be a 10DC-1

 

[mbz]

Photo shows this to be a 14D, parts list and schematic show this to be a 10DC-1

Happy to admit when I'm wrong but if you take a closer look at the item it's marked as a "10DC". Possibly the "1" on the other side is the variant, ie, "10DC-1" and the "4D" manufacturing info.


Yep, half wave rectifier, the complement/common anode (10DC-1R) is not needed

 

[Yamaha5000]

Should I replace all of these in that channel?

2SA745 - MJ21193
2SC1403 MJ21194

 

[Yamaha5000]