[BUILD] CAPI VP28~500 Series~2-Stage Preamp~Official Support Thread

[Commander Fluffypants]

Sorry for spamming with these questions. Looking at what I had tried to do, perhaps I don't know how to count gold fingers... Do we count only the ones on the card or do we count the spaces where there *could* have been more? I did the latter. It's not making sense to me now. Also, when Jeff says I can get ground at the gold pad next to gold finger five, I have no idea what gold pad he's talking about. I don't even remember where I stuck the ground lead when I tested this thing back in May.

 

[jsteiger]

The VPR protocol has 15 gold fingers. They are number 1 thru 15 with 1 being at the top edge of the card. It makes no difference if some of the pads are left off. They are still numbered 1 thru 15 from the top to the bottom so if they are missing you need to count the spaces. There is a small thru hole via adjacent to gold finger #5 that makes for an easy spot to get a ground reference.

 

[Commander Fluffypants]

Thank you! I actually understand what you're saying. I will retest this thing tomorrow night.

Another question:

Do the DOA's need to be in it when I test it?

 

[Commander Fluffypants]

OK. I tested it again and got no reading either pad. I did notice that the green signal present LED blinked on every time I touched gold finger 5. Even if I held the probe in place, it would just blink at first contact and then go out. No blinding when testing gold finger 10. Not sure if this information is relevant, but it's the only thing that I noticed happening.

What's next?

 

[jsteiger]

Not sure if I asked you for this before but measure DCR between the following gold fingers:
5 to 8
5 to 10
8 to 10

If you have a manual DMM be careful of the range setting. We are looking for a close to direct short.

 

[Commander Fluffypants]

Thank you again for the help!

I just want to clarify in terms that a drummer can understand...

I did the tests with one probe on pad 5 and then moved the other probe to both 8 and 10. You want me to also put one probe on 8 with the other on 10? Does it matter which probe goes where? What range should y DMM be set to? When I tested last night, I moved through all the ranges. I first tested it  with black on ground and red on the 8 and 10, and then tried it the other way. No readings at all either way.

Oops, correction:  When I tested last night, the signal present light blinked when I touched pad 8 while also touching pad 5. Touching pad 8 alone did nothing. Touching pads 5 and 10 did nothing.

 

[jsteiger]

We are looking for a direct short here so the module should not be racked and not under power. Your DMM needs to be set to read DCR. Same as if you were measuring resistors.

 

[Commander Fluffypants]

DOH!

Got it.

 

[Commander Fluffypants]

Not sure if I asked you for this before but measure DCR between the following gold fingers:
5 to 8
5 to 10
8 to 10

If you have a manual DMM be careful of the range setting. We are looking for a close to direct short.

I get 8.58k between 5 and 8 and also between 5and 10.

I get 9.97k between 8 and 10.

What does that tell us?

 

[jsteiger]

That tells me its in Line mode. I should have specified to put 'er in Mic mode.

 

[Commander Fluffypants]

That tells me its in Line mode. I should have specified to put 'er in Mic mode.

I'm glad I refreshed the screen before shutting down for the night! Thanks for the quick reply!

5 to 8 and 5 to 10 are both now 3.61

8 to 10 is now 27.5

 

[jsteiger]

With the Mic button in and all others out, you should have 3k6Ω from 5 to 8 and 5 to 10. Between 8 and 10 will be around 29Ω.

 

[Commander Fluffypants]

With the Mic button in and all others out, you should have 3k6Ω from 5 to 8 and 5 to 10. Between 8 and 10 will be around 29Ω.

This is what I have (almost.)  3.61k for 5 to 8 and 5 to 10 and 27.5 for 8 to 10.

 

[Commander Fluffypants]

Bumping. Should be able to work on this more tonight. What's the next thing for me to do or check?

Thanks

 

[Commander Fluffypants]

With the Mic button in and all others out, you should have 3k6Ω from 5 to 8 and 5 to 10. Between 8 and 10 will be around 29Ω.

This is what I have (almost.)  3.61k for 5 to 8 and 5 to 10 and 27.5 for 8 to 10.

Quoting and bumping again.  I may have some time to work on this tonight. What's my next step? What should I try?

Thanks again.

 

[AudioHak]

Hi guys! I too have the green light problem happening. When I power up the unit, it passes signal perfectly with good tone, however the green light stays lit until the gain knob is turned to the center position. It then turns off and functions normally. Is there any way to remedy this? Thank you.

Hey Jeff and everyone else,

I too am experiencing a similar problem on a new build. I searched, but was not able to find any responses to this problem.  The green signal led stays lit when I first power up the module, but strangely, when I turn on phantom power, the signal led functions as normal. Turn phantom back off, the signal led goes back to constantly lit. Another odd behavior I have noticed is that around 30 minutes of use, the signal led begins to function as normal, regardless of the 48v phantom switch position. Kinda stumped on this one. Everything looks like its correct. Signal passes fine and the preamp sounds fantastic.

Things I have tried:
    Changing the op-amps for known working op-amps.
    Reheating connections that are in the path.
    = Same behavior.

Could this be a faulty chip? What would cause it to function normally once heated and running for 30ish minutes?
Any help is appreciated.

 

[AudioHak]

Over the holiday I finished my second vp28. Looks like it's having the same problem. Signal led stays lit unless I push the 48v button. Then functions as normal. Yes this is with any type of mic.

Any ideas?

 

[jsteiger]

Over the holiday I finished my second vp28. Looks like it's having the same problem. Signal led stays lit unless I push the 48v button. Then functions as normal. Yes this is with any type of mic.

Any ideas?

What board Rev are these? Black Rev A or green Rev B?

 

[AudioHak]

What board Rev are these? Black Rev A or green Rev B?

Both are green Rev B.

 

[jsteiger]

Both are green Rev B.

Hmm, OK this is the first issue I have heard of with the signal present on the new PCB. If both are acting the same, it is likely the same build error on both or possibly a rack situation? What rack are you using?