Salas SSLV1.3 UltraBiB shunt regulator

[gaszto]

I've replaced both of BC560C. Q2 Vbe 166mV Q3 Vbe 3.45V
M1 voltage between leg 1-3 is 11.56V (same as output voltage) M2 voltage between leg 1-3 0.585mV. Rload checked 99.6Ohm

Sorry the measured value on M2 is 585mV not 0.585mV

M1 must be wrong type or broken

I've replaced M1, but the voltage between 1-3 is 11.56 after the replacement. Not changed.


The measured M2 voltage is correct or is it too low?

 

[Salas]

Should have been 3-4V

 

[Salas]

If you don't have a component tester see: #132: How to test MOSFETs with a DMM - a few methods... - YouTube

 

[gaszto]

I desoldered M2. According to the component tester N-E-MOS C=1.5nF Vt=3.0V

 

[Salas]

That's typically alright. Weird. Some joint or something TO-92 must not be working properly. The circuit connections should also check out good with the continuity buzzer.

 

[gaszto]

I've put a new M2. I resoldered every joint. (I never had soldering problem) I measured the voltage drop on the R7 and still 0.5-1mV... and the led illuminating very low light. I measured again J1-J3 all between 85 and 100Ohm. I really don't understand. I changed the potmeter, Q2, Q3 M1, M2...


One year ago I made my own version of UltraBiB to one sided pcb, for home production. It worked first time, but a bit noisy. (I think, because of the pcb arrangement) Therefore I bought an official pcb with minikit to be sure everything will be perfect. My DAC don't want the perfect PSU
Thanks again for the patient and the help for the troubleshooting.

 

[Salas]

Is there a possibility some 270R is 2K7 or 27K by mistake?

 

[fedde]

Maybe you can make a photo gaszto?

 

[gaszto]

I attached photos from it. Maybe it's help

 

[gaszto]

Is there a possibility some 270R is 2K7 or 27K by mistake?

All of 270R and 51R are Dale RN60D from Mouser. I measured the first, when I opened the package, and all are the same. The text are visible 2700F is the 270 Ohm, and 51R0F is the 51 ohm. 470Ohm resistor is PRP

 

[fedde]

Vrr is missing...

 

[jimk04]

Is VRR populated underneath?

 

[jimk04]

Nice timing!

 

[gaszto]

Is VRR populated underneath?

yes, i replaced Vrr. and now it is located under the pcb.

 

[gaszto]

This is how the output looks like

 

[Salas]

This is raw DC with ripple. Behaves like no circuit is there after the rectification.

 

[Salas]

What type M1 is used?

 

[gaszto]

Onsemi FQP3P20
I replaced it because I measured 11.56V between leg 1-3, but after the replacement I also measured 11.56V between leg 1-3. Is it ok?


The voltage drop on R7 is only a few mV and the Leds illuminating very low light.

 

[Salas]

Do you have any other PMOS around to replace, like IRF9610 or similar? Is there normal Vbe on Q1?

*M1 in a working situation should have about 4V Vgs if IRF or 1-2V more if FQP

 

[Salas]

Does the component tester recognize the previous FQP you replaced?