[BUILD] CAPI VP2X~500 Series~Preamp Kit~Official Support Thread

[kikovazquez]

i have weird issue i have
two vp 26 and one is fine and working propertly the other one is half quieter even o. the loudest setting i dont know were to start the touble shoot i swaped in diffrent chassis same issue!!!!

 

[Ricardus]

i have weird issue i have
two vp 26 and one is fine and working propertly the other one is half quieter even o. the loudest setting i dont know were to start the touble shoot i swaped in diffrent chassis same issue!!!!

Upload some hi res pics of the top and bottom of the boards.

 

[kikovazquez]

Upload some hi res pics of the top and bottom of the boards.

here they are

 

[kikovazquez]

nobody?

 

[jsteiger]

nobody?

I cannot make out the R color bands in that pic.

If you have a good working unit, you could compare them visually. Then inject signal and trace it comparing them to see where things change.

 

[Ricardus]

nobody?

I don't see anything obviously wrong in those pics. The soldering could be better but I don't think that would be causing your issues.

 

[Harpo]

... the other one is half quieter ...

doublecheck parts value of feedback resistor R5 being 20K for real (R4 was the part ID from a previous pcb revision), not mistakenly fitted 10K instead ... There are not so many possibilities on this pcb causing a factor 2 or 0.5 error.

edit: corrected part ID

 

[kikovazquez]

double check parts value of feedback resistor R4 for 20K, not mistakenly fitted 10K ...

values on the resistors
and their position on the r7 and r8 the values as half of what is supposed!!!

 

[jsteiger]

values on the resistors
and their position on the r7 and r8 the values as half of what is supposed!!!

Resistors cannot be measured with both ends soldered in circuit. You will get misleading results. At this point reading the color bands is the best way.

Was this pre working fine at some previous point and then stopped?

 

[kikovazquez]

Resistors cannot be measured with both ends soldered in circuit. You will get misleading results. At this point reading the color bands is the best way.

Was this pre working fine at some previous point and then stopped?

no it never

i builded
and was
in storage
for a while

 

[Ricardus]

Take a very well lit pic of the top of the board so we can see resistor colors.

 

[kikovazquez]

Take a very well let pic of the top of the board so we can see resistor colors.

i will thanks

 

[kikovazquez]

i will thanks

 

[jsteiger]

OK, you've got 150k placed for R10 and that should be 160R. You basically flipped the locations for R3 and R10. That will indeed cause major level issues. R3 should be the 150k.

 

[kikovazquez]

fixed thanks

 

[wjohn]

Built my first CAPI pre (VP25) this weekend - it sounds great!
I built the very helpful extension jig also.
Thanks to Jeff and the team for a fantastic kit and documentation!
I've got a pair of VP26s, a VP28, a 312DI, and some DOA kits to keep me busy soldering over the next month or two.

 

[wjohn]

Built my pair of VP26 kits this weekend and both worked.
Going through each step on two builds at a time seemed to make it go faster.

 

[Hillie]

Please pardon my stupidity, but does the Bourns t-pad attenuator on the VP26 have a click/clunk-detent for the -inf value on the panel? I just put one together and I matched the dot of the knob with the 0 on the panel with the pot all the way open, but turning CCW makes it stop at the line before the -inf sign. I feel quite a bit of resistance and don't want to break the pot by forcing it, therefore my question.

 

[jsteiger]

Please pardon my stupidity, but does the Bourns t-pad attenuator on the VP26 have a click/clunk-detent for the -inf value on the panel? I just put one together and I matched the dot of the knob with the 0 on the panel with the pot all the way open, but turning CCW makes it stop at the line before the -inf sign. I feel quite a bit of resistance and don't want to break the pot by forcing it, therefore my question.

There is no detent. The actual rotation is just a few degrees short of the screen print.

 

[danmorse]

Hi all. I've built two VP26s and two VP312s, all with no issues, but now after maybe 2 years of working well one of my VP26 pres is very quiet and a bit distorted. Sound does pass through, but it's really quiet. I tried swapping out the opamp (Rogue Five DOA 1.3), tried a different slot in my 500 series rack (Vintage King Rack 500), but no luck so far. Any advice? Attaching a picture in case it helps. Many thanks for any ideas...