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

[fucho!]

??? Oh No!!! The unit went south again for no apparent reason. It's outputting a whopping 30db quieter than the second. This is true for both condensers and dynamics, with pad & phase engaged/disengaged. I went back and retouched again but to no avail. I've retouched the whole board several times now, and really don't want to put any more stress on it. The resistance tests between V+, V-, C, & 0 all read fine. I switched out the op amps and this had no effect. Everything read correctly before I populated the board. I double checked the 750R resistors in the R10 & R11 slots and they are indeed 750Rs. Any other ideas??

 

[Brolik]

Thanks for the suggestions Jeff. I replaced the 10k R6 with a 220 ohm (didn't have a 200, close enough?) flipped the phantom switch wiring to the other side and retouched all the solder joints on the PCB. Still the same static when I flip the phantom power on. Still works, but still noisy.

Any other suggestions? Is there a chance that getting an actual 200 ohm for R6 will make a difference?

I think I'm going to replace the phantom switch and wiring next.

By the way my VP312DI is healthy as a horse and sounds great!

Thanks.

 

[jsteiger]

Thanks for the suggestions Jeff. I replaced the 10k R6 with a 220 ohm (didn't have a 200, close enough?) flipped the phantom switch wiring to the other side and retouched all the solder joints on the PCB. Still the same static when I flip the phantom power on. Still works, but still noisy.

Any other suggestions? Is there a chance that getting an actual 200 ohm for R6 will make a difference?

I think I'm going to replace the phantom switch and wiring next.

By the way my VP312DI is healthy as a horse and sounds great!

Thanks.

220R should be close enough. I don't think this will make any difference here really. It is possibly the switch. If you have ruled out all other outside possibilities (rack slot and all related cabling) You can try the switch. Not that it couldn't happen but it would be the first bad one out of a few thousand. The phantom circuit is really almost nothing so not a whole lot to go wrong.

 

[Brolik]

Thanks Jeff. That's what mystifies me, there's almost nothing there so what the hell could go wrong? I've tried it in several slots (all that work) and with cabling that is in use with working gear, so thats covered. I'm going to try the switch, but that doesn't seem that likely to me either as the phantom power itself works, just noisily. Here's some pics of the build in question.
http://www.flickr.com/photos/58015312@N04/sets/

 

[Brolik]

Just an update on my progress. I've replaced the phantom switch and wiring, retouched all pcb solder joints and replaced R6 with 220 ohm. Still got that damn crackle when the 48v is engaged. Also, it makes a pretty substantial pop when the switch is hit, louder than on the working vp312. I'm gonna work my way back and try switching out C9 next. Let me know if you have any suggestions.

 

[jsteiger]

Might be a silly question but have you 100% ruled out rack-slot and all cabling? Don't know if you are testing this on your bench or not. I have heard more of these problems get solved with cable issues over others. Pardon me if I already mentioned this. Just a thought.

 

[Brolik]

Not silly at all, stupider things have happened. Just to be sure, I popped it into the slot that the working VP312 was in with the same results. Wish it was just a bum wire, that would be easy to fix.    Guess I'll just keep pokin...  :

 

[zmgwg]

has anyone build one without the T-pad attenuator? how should I do/wire it?

 

[jsteiger]

Yes, I have had a lot of guys do this. Just jumper from Pad A to Pad C on the main PCB (near where the t-pad would go). Make sure you stay away from Pad B. That's it!

Best, Jeff

 

[sea_man]

Hi !

I bought a VP26 complete kit.. but i have a question about the transformer wiring.

i have the board rev A.2 and the transformer EA2623-1 ( whit different color order ( from right to left in this order: red, yellow, blue, gren, brown, black ) , i need make any modification whit the wires colors or can i connect whit the colors in the PCB directly ? ( ie.. black to black blue to blue .....)

Thanks !

 

[jsteiger]

( ie.. black to black blue to blue .....)

Yes, the order is different but the colors are still the same so black to black, blue to blue and so on. You will need to cut the leads to different lengths than what the Assembly Guide shows though so be careful there!!

Best, Jeff

 

[sea_man]

Thanks !

Now my two VP26 are ready !  8)

Some pics:

http://www.flickr.com/photos/mar1o_bross/sets/72157627001844167/

 

[etheory]

I haven't yet turned it on for testing, but here is a link to the build of another beautiful-looking VP26:
http://www.evolutionarytheory.com/2011/08/classicapi-vp26-build/
Thanks Jeff!

 

[etheory]

For those here who are interested, here is the first part of racking a VP26 up ( along with an MP73 ).  I will post the other 2 parts once they are done:

http://www.evolutionarytheory.com/2011/08/boxing-an-mp73-and-a-vp26-part-1/

 

[bigevil]

This is going to be my first real DIY build and I can't wait(aside from some random led kits I did to practice soldering.) Prepare for newbie stupidity coming your way or maybe surprising myself and us all and it just working first time. I'll go slow and be tedious and keep you posted if I've got questions. I'd love to show other newcomers to this hobby that its possible to build this kit if you are diligent and willing to read all the wonderful help on this forum ...... hmmm, we'll certainly find out soon enough!


in the meantime........ here's the panel I had made for it. Kinda went overboard but its a gift for my brother (he's got the lunchbox).

 

[vDo]

Hey folks,

I'm new to the thread and a very new DIYer. Thanks to Jeff for pointing out this thread (that was right beneath my nose in the documents he provided)

I've assembled a VP25 w/ a stepped gainswitch and a Gar1731 DOA (kit)
(The DOA and stepped gain definitely tested my novice soldering skills for sure)

Heres where i'm at:

Audio passes through but its super thin and nasty at higher volumes.
Gainswitch - works
Mute - works
Phase - DOES NOT WORK - cuts signal totally
Pad - works

Output - worked seemingly backwards at first, but after some retouches all over the place it was working normal - then effed the leads up by accident so i redid them - now its seems backwards again.

When testing the DOA sockets on the board I got a weak reading between C and O - then i retouched things a bit and i got a better reading.. but its doesn't seem to be consistent.

I've retouched any joints that looked shady - but surely i'm missing something.

Any and all input would be super appreciated - super newbie here - i'm all ears.

Thanks
Max

 

[jsteiger]

Max

I would suggest resoldering the pins for the 3 C&K pushbutton switches. Those are the biggest stumbling block for guys. The pins that connect to the ground plane are a little harder to get a good joint on. A few pics could help to, especially around the t-pad area.

Also, what DOA are you using? If it's a kit, then that can be another can of worms. Either way, make sure you check out my DOA install page for some tips. http://classicapi.com/catalog/DOA_Install.php

Cheers, Jeff

 

[vDo]

Max

I would suggest resoldering the pins for the 3 C&K pushbutton switches. Those are the biggest stumbling block for guys. The pins that connect to the ground plane are a little harder to get a good joint on. A few pics could help to, especially around the t-pad area.

Also, what DOA are you using? If it's a kit, then that can be another can of worms. Either way, make sure you check out my DOA install page for some tips. http://classicapi.com/catalog/DOA_Install.php

Cheers, Jeff

Hey there! Thanks for the advice. Here are some pics down below - you can see its pretty amateur hour. After reading through the whole thread - I retouched as many shoddy joints as i could before posting my questions - I might have gone too far.

When you say to resolder the pins - should i just remove all three switches, clean it all up as much as i can and start totally fresh - following the instructions in the guide?

As far as the DOA - yes i got the Gar1731 full kit bundle. I should have started with an assembled one - I'm not proficient enough yet for that build. Very likely a mistake lies within there.. though i thought the nature of DOAs was to either work or not work..? (not sure where that came from..)
Pretty sure I got the seating figured out though as I did review your 'DOA Install Guide' - Thanks!

Should I try to locate or just buy a new tested and functioning DOA? Then i'd know what works, and flush out any other mistakes from there - and then i'd also have a reference to compare my build to..

Super thanks for the help!

 

[vDo]

another pic - am i missing something bout posting multiple pics?

 

[vDo]

and one more..