[Alex Harmer]

Hi JP,

I initially successfully passed step 5 with this unit, and everything worked until step 11… when pressing down the BYPASS switch to get 0.98VAC produced no change.

After much trying, I decided to try from the beginning.

Now I can’t get past step 5.

I am getting +16vDC and -16vDC no problem.

But I only see 0.064vDC across TP2 and TP3. TR2 takes a lot of turns, and it only changes a little.

I have reflowed all solder on PCB1 and checked orientation.

Thank you!

[Alex Harmer]

Here are my results from your first aid test:

Threshold switch position		TP4 & TP5 AC voltage		JMP1 between pin1 DC voltage and +input on PCB 2 (I didn't know where else to put the probe)
+6dB		0.00 (supposed to be 0.11V)		1.8 VDC (supposed to be 0.14V)
0dB		0.00 (supposed to be 0.22V)		1.9 VDC (supposed to be 3V)
-6dB		0.00 (supposed to be 0.45V)		1.9VDC (supposed to be 10.8V)
-21dB		0.00 (supposed to be 2.4V)		2.03VDC (supposed to be 15V)

[JPK]

But I only see 0.064vDC across TP2 and TP3.

(Without left PCB installed)
Check the connections to the output transformer.
What DC voltage do you get on the yellow wire, against 0V ?
What DC voltage do you get on TP3, against 0V ?
Check the solder joints on Q7, trimmer TR2 and R31.

[Alex Harmer]

Thanks for your reply JPK! By the way - the first unit is sounding wonderful thank you!

(Without left PCB installed)
Check the connections to the output transformer.
What DC voltage do you get on the yellow wire, against 0V ? = 15.42
What DC voltage do you get on TP3, against 0V ? = 14.35
Check the solder joints on Q7, trimmer TR2 and R31. = completed! No issues. I de-soldered and reflowed just in case.

Step 5 result of VDC across TP2 & TP3 is 0.046 VDC with TR2 turned all the way clockwise.

[JPK]

TP3 should be around -11VDC.
Check Zener D20. It could be dead.

[Alex Harmer]

Check Zener D20. It could be dead.

I think you're right! I removed Z4V7 1W3 in D20 and my meter said OL in both directions on the diode test. I then put the diode back in circuit and tested it with normal power. Same result.

Is this the correct Mouser part?

https://nz.mouser.com/ProductDetail/Vishay-Semiconductors/BZX85C4V7-TAP?qs=yIvl1B2wDi7Hji4YUWzsdQ%3D%3D

I'm having trouble finding the right replacement part in my city. No local suppliers have 1W3.

Would it be okay to replace it with a 3W?

[JPK]

Is this the correct Mouser part?
Yes, correct.

Would it be okay to replace it with a 3W?
Yes, no problem.

[Alex Harmer]

All sorted JPK!

Both units working perfectly, and sounding amazing.

I'll do a demonstration for YouTube if you would like to look out for it

[JPK]

Can't wait!