[BUILD] CAPI VP312DI~500/51x Series~Preamp + Direct Inject~Official Support Thread

jsteiger said:

Well, I guess I was also asking you if you for sure identified the 4V3 zener diodes and made positive they went in the right location. If you say no, then you have a 33.33% chance they are right.  :-\

I am pretty certain PK2 is done wrong. I can't really see the part label for CR2 in the pics. The angle is not good. Maybe you can figure this out. Go back and verify what the label should be by viewing 'Chunger's build thread. Your pics are clear enough when I zoom in but the angle is not the best.

Click to expand...

Yeah, it was wrong and i corrected it, its weird, now the DI sounds more natural and without distortion, but when i connect a mic nothing happens... i thought it was the stepped attenuator but despite some knob issues, it does what it's supposed to when i connect a di guitar... could it be i didnt use tape between the 2622's and the pcb? :O

Pliplo said:

... could it be i didnt use tape between the 2622's and the pcb? :O

Click to expand...

No that won't be it. Did you still have a 1/4" plug in the 1/4" jack when trying the mic? The 1/4" jack controls the PK2 relay so when a plug is inserted, it switches to DI mode. With no plug it is in mic mode.

jsteiger said:

Pliplo said:

... could it be i didnt use tape between the 2622's and the pcb? :O

Click to expand...

No that won't be it. Did you still have a 1/4" plug in the 1/4" jack when trying the mic? The 1/4" jack controls the PK2 relay so when a plug is inserted, it switches to DI mode. With no plug it is in mic mode.

Click to expand...

Yeah i just noticed it cause i assembled my 2nd VP312DI and im proud to say everything seems to be working fine (minus the re led, i dont know wth is up with it hehe)... Tho i only get DI guitar tone when i engage the post2622 switch... that isnt normal is it?

still was a triumph hehe...

Pliplo said:

.....everything seems to be working fine (minus the re led, i dont know wth is up with it hehe)... Tho i only get DI guitar tone when i engage the post2622 switch... that isnt normal is it?

Click to expand...

If the phantom LED doesn't work, it is most likely backwards. Forgot to mention before that it is normal for the LED to fade over a few seconds when turning off the phantom. That is just the draining of the 120uF cap.

If the "pre 2622" setting does not work, that will probably be the HiZ Plug-In circuit. Swap in a different Plug-In and see if it helps. I don't recall if you have any of the Pikatron passive versions but they are easiest to test with since build errors with them are virtually nonexistent.

jsteiger said:

Pliplo said:

.....everything seems to be working fine (minus the re led, i dont know wth is up with it hehe)... Tho i only get DI guitar tone when i engage the post2622 switch... that isnt normal is it?

Click to expand...

If the phantom LED doesn't work, it is most likely backwards. Forgot to mention before that it is normal for the LED to fade over a few seconds when turning off the phantom. That is just the draining of the 120uF cap.

If the "pre 2622" setting does not work, that will probably be the HiZ Plug-In circuit. Swap in a different Plug-In and see if it helps. I don't recall if you have any of the Pikatron passive versions but they are easiest to test with since build errors with them are virtually nonexistent.

Click to expand...

It was backwards... And you were right about the HiZ, there was some sloppy soldering apparently, i re-flowed and now everything's working, i got my first 100% working VP312DI (tho the front-plate assembly is mediocre, hope this doesnt brake it in the long run)

Now im off to find the mistake in my first vp312di, mic signal isnt there...

I would look at the 4V3 zener diode on PK2.

Glad you are up an running with at least one! 

jsteiger said:

I would look at the 4V3 zener diode on PK2.

Glad you are up an running with at least one! 

Click to expand...

im pretty sure the zeners are ok now, i did correct one that was wrong... i've been reflowing some questionable joints but still no mic signal through... i did notice some things that i hope can help the diagnosis... DI works just fine... when i unplugged the guitar and went for mic signal, i notice i get a lot of noise in when i activate the DI's -10db pad, and also noticed a lot of noise when i turned the lunchbox off... The crappy thing is a have a good DMM but i dont know where to probe or what the obtained results would mean =P

Do you have a way to power your modules without being in a rack? A bench supply of sorts?

jsteiger said:

Do you have a way to power your modules without being in a rack? A bench supply of sorts?

Click to expand...

nope, that would be cool, i already am into that, but apart from the blue 30 pin card edge connector i dont know what else is needed  hehe

well, since i already assembled the other 9 modules, ive been checking the malfunctioning VP312DI... i had a couple diodes of the rilays mixed up, and i mixed up C12 and C13 too... Its all been fixed but i still cant get mic signal, could i have harmed something with stuff in the wrong position? DI still works fine (and did with the diodes and c12/c13 mixup)

You need to see if that PK2 relay is functioning right. The relay should flip when you insert a 1/4" plug in the DI jack. If it is not being activated, I would most likely think it is something on the PK2 board.

jsteiger said:

You need to see if that PK2 relay is functioning right. The relay should flip when you insert a 1/4" plug in the DI jack. If it is not being activated, I would most likely think it is something on the PK2 board.

Click to expand...

Flip would mean "emmit a small contact noise"? ... Is there a way to check if the PK2 relay is functioning right with a DMM? I have a Fluke 115

You can beep for continuity between the A+ pin and the O+ pin (mic mode). Next would be the B+ pin to the O+ pin (DI mode). This info is on the skiz. There is just enough room where the 90 degree header comes out of the relay PCB to get your probe tips in. If this relay is not flipping with the plug going in/out of the DI jack, it's either a problem on the PK2 relay build or the control signal which can also be followed on the schematic. You must have DC applied to the main board for this to work.

jsteiger said:

You can beep for continuity between the A+ pin and the O+ pin (mic mode). Next would be the B+ pin to the O+ pin (DI mode). This info is on the skiz. There is just enough room where the 90 degree header comes out of the relay PCB to get your probe tips in. If this relay is not flipping with the plug going in/out of the DI jack, it's either a problem on the PK2 relay build or the control signal which can also be followed on the schematic. You must have DC applied to the main board for this to work.

Click to expand...

I just tested that and everything beeps exept B+ to O+ (di mode) in the relay that's next to the neutrik connector. It was impossible to get there so i "assembled" the module just with the faceplate (no L bracket) and tested from the back in my empty lunchbox. Any ideas?

The relay in question that selects what input goes to the 2622 (mic or HiZ Plug-In) is PK2 that is situated more in the center of the PCB just behind the input transformer.

PK1 routes the DI input signal to the HiZ Plug-in or to the post 2622 position. You need to flip the mini toggle on the front to get this relay to active/deactivate. This can only happen with a plug in the DI jack.

jsteiger said:

The relay in question that selects what input goes to the 2622 (mic or HiZ Plug-In) is PK2 that is situated more in the center of the PCB just behind the input transformer.

PK1 routes the DI input signal to the HiZ Plug-in or to the post 2622 position. You need to flip the mini toggle on the front to get this relay to active/deactivate. This can only happen with a plug in the DI jack.

Click to expand...

Ok, so the relay in question is working... But still no mic signal, any other idea Jeff? I bought a hakko desoldering station recently, i think we're approaching the point where i buy another pcb and some parts and redo it...

Do you get a DI signal thru the HiZ Plug-In?

jsteiger said:

Do you get a DI signal thru the HiZ Plug-In?

Click to expand...

yes i do

Well, I can't think of any reason why the mic in won't work then. If the relay PK2 board is fine, then the only difference between the output of that relay card from DI mode to mic mode, are a few inches of PCB traces and the gold fingers #8 and #10. Is this maybe an issue that lies between the card and the mic? Meaning rack or outside cabling?

What i just noticed is that the POST 2622 switch doesnt appear to do anything, just a minor noise when i flip it but no change in sound. And the -10 pad next to it engages regardless of the post2622 switch's position. the LPF doesnt seem to be doing anything either.