PJCCS

[Tubeman]

I added a PJCCS to an existing Quickie 1.1 and am seeing the following test voltages:

1A 4.5V
1B 3V
6A 34.7V
6B 22.7V
5A 2.8V
5B 1.5V

All of the solder joints on the PCB look good and if I swap the tubes left to right the test voltages are approximately the same.
Any troubleshooting suggestions are appreciated. 

 

[Paul Birkeland]

I don't know what your voltage numbers reference.  The PC board has IA, IB, OA, OB, BA, BB, KregA, and KregB.

If 1A and 1B are supposed to be IA and IB, those are wired directly to the 9V battery stack, so seeing 4.5V on one and 3V on the other (they are wired together!) would mean that possibly a 9V battery is missing or open, or the battery pack is not well connected to the PC board.

If 6A and 6B are supposed to be OA and OB, seeing 34 and 22V at those terminals would not make a lot of sense if there's only 3-4V at the input terminals of the PC board.

Perhaps you could post some build photos?

 

[Tubeman]

Paul

Thank you for your quick reply.
Unfortunately, I understood test points IA and IB to be tube terminals 1A and 1B designated in the quickie manual.
Below please find the test voltages I observed at the following test points:
IA 35.3V (Same voltage as 9 volt battery pack)
IB 35.3V
OA 34.6V
OB 22.1V
Kreg A 4.2V
Kreg B 3.0V 

All measurements were made with the PJCCS connected to the Quickie with the tubes installed and the heaters powered.

Thanks again for any guidance and sorry for the misunderstanding.

 

[Paul Birkeland]

One side seems to be working and one side does not.  If you can post build photos, we may be able to spot what's going on.

 

[Tubeman]

Paul,
Attached please find two photos of the PJCCS.

 

[Paul Birkeland]

From your photos I can't see the bottom of the PC board, the orientation of the UF4007 diodes, nor the rest of the Quickie build.

Since you have one working channel and one dead channel, be sure everything is consistent between sides.  Beyond that you're very likely looking at a loose connection or flaky solder joint, but do keep in mind that this could be in your original build and not the PJCCS board itself.

 

[Tubeman]

Paul,

Is there a way to troubleshoot the PJCCS without it being connected to the Quickie?
Both channels of the Quickie 1.1 amp work perfectly with the stock 4K plate resistor installed (2ma of plate current on both channels).
When I hook up the PJCCS to the Quickie OA measures 2.7ma and OB measures 1.2ma with the expected difference in gain between the channels.
Both OA and OB only conduct when the tube filaments are powered.
All the solder joints on the PJCCS look good and the diodes are oriented correctly.
Suggestions are appreciated.
 

 

[Paul Birkeland]

Is there a way to troubleshoot the PJCCS without it being connected to the Quickie?

No, but providing ample extra photos would be a good start.

 

[Tubeman]

Plese see photos of the attached PJCCS attached.
If you need any additional photos, please let me know.

 

[Paul Birkeland]

You must have bought that kit on a pretty early run of the PJCCS.  There was an error in the very original manual that we subsequently corrected.  If you PM me your e-mail address I can send you a copy of the last manual revision that's more up to date and properly shuts the circuit down when powered off.

 

[Tubeman]

My email address is ktswoope@aol.com

 

[Paul Birkeland]

YGM.

 

[Tubeman]

Got it.
Hopefully this gets it working.
Thank You.

 

[Tubeman]

Paul,

I made the changes to the PJCCS suggested in the revised manual and now see the following test voltages.
IA 34.9V
IB 34.9V
A6 34.2V
B6 23.8V
A5 2.8V
B5 1.7V

The CCS only conducts when the tube filaments are powered.
Attached please find photos of the revised build.
Any other suggestions are appreciated.

 

[Paul Birkeland]

If you flip the board  and connections 180 degrees, does the problematic voltage move to B6?

 

[Tubeman]

Yes.
Here are the test voltages with the A and B connections reversed:

IA 34.9V
IB 34.9V
A6 24V
B6 34.2V
A5 2.8V
B5 1.7V

 

[Paul Birkeland]

This tells you there's something wrong outside the PJCCS.  It could be something simple like a battery in backwards or a tube that is rather dead, so perhaps the best next step would be to swap 3S4s between sides to see if the bad voltage moves back to the A output of the PJCCS.

 

[Tubeman]

If I swap the tubes the tubes the test voltages on the A and B side stay the same and I verified that the D batteries are installed correctly.
The maddening thing is that the preamp functions perfectly with the 4K plate resistor installed.

 

[Paul Birkeland]

Can you show photos of the entire build with the PJCCS installed?

 

[Tubeman]

Paul,

I believe that the problem was probably a defective PCB.
I built another PJCCCS kit that I had and installed it on the Quickie according to the updated assembly manual that you sent me and the test voltages are correct and the preamp functions properly.
Thank you for emailing me the updated manual.