[Build] CAPI VP312~500/51x Series~Preamp Kit~Official Support Thread

[Potato Cakes]

The Out Lo is still connected (see schematic) so there will be something, but it should be very low output and possibly sounding very thin.

Take your meter and one at a time measure resistance for the wiper and CW for all three sections of the T-Pad while turning it. Then do the same for the wiper and CCW. If the resistance changes for each one then it should be good and there is a soldering issue.

Thanks!

Paul

 

[the new frenchy]

Ok Thanks Paul!
It's wright it's a very little sound very thiny...
I must soldering again RV1, if I understand! Cause it is a little bit damage, I prefer get a knew one! Can I buy it in France do you know?
And my family arrive I must welcome them.... so sorry.... But very thanks about all this advice! I give you some news when I have a new RV1!
Very thanks!
read you

 

[Potato Cakes]

In the meantime you can swap it with one that is working to verify.

Thanks!

Paul

 

[Winetree]

Is there any known way to replace or repair the 51X (24 volt) tab that has be removed from the P.S.B.?

 

[the new frenchy]

Hi Paul! With a new output pot, the problem is gone! All my preamp is Ok! thx a lot for your help!

 

[Potato Cakes]

Hi Paul! With a new output pot, the problem is gone! All my preamp is Ok! thx a lot for your help!

You are welcome! Enjoy that sweet preamp.

Thanks!

Paul

 

[haselnusse]

Hi all,

i just finished builing 4 VP312s and by accident noticed a small amount of microphonics on all 4 units when tapping at the knobs with no mic connected and max gain, anybody experienced that before? all components are mounted tight to the PCBs...

cheers

 

[jsteiger]

Hi all,

i just finished builing 4 VP312s and by accident noticed a small amount of microphonics on all 4 units when tapping at the knobs with no mic connected and max gain, anybody experienced that before? all components are mounted tight to the PCBs...

cheers

I have never checked this way but not sure its relevant since the input should be terminated in some way. What rack is this BTW?

 

[haselnusse]

A Lindell 510 (the old rev without the D-sub connectors on the back). Never noticed any microphonics before with the two VP28 and some homebuilt modules... i will do some more testing today.

thanks for the fast reply!

 

[haselnusse]

Hi,

i recently encountered a problem with one of my VP312s, it started making weird wind-like noises and crackled from time to time. When i engage the pad or switch the polarity there is a loud pop which almost clips my AD - way louder than on any of the other VP312. Also there is some microphonics when i lightly hit the frontplate with my finger. What could the problem be?

Here is what i did:

- carefully reflowed all solder joints, especially around the switches, trying not to overheat them
- checked all traces for continuity
- measured DCR as mentioned in the VPXX build assembly guide

The opamp checks out fine, works like a charm in any other of my Pres.

Any help would be much appreciated!

 

[jsteiger]

Hi,

i recently encountered a problem with one of my VP312s, it started making weird wind-like noises and crackled from time to time. When i engage the pad or switch the polarity there is a loud pop which almost clips my AD - way louder than on any of the other VP312. Also there is some microphonics when i lightly hit the frontplate with my finger. What could the problem be?

Sounds like a bad solder joint to me.

Could also be a rack issue. What rack is it?

 

[haselnusse]

Thanks for the fast answer!
It is a Lindell 510 (the first version without the sub25 connnectors).
Could it be that i overheated the Pad switch when soldering it in or reflowing the solder joints?

 

[jsteiger]

Thanks for the fast answer!
It is a Lindell 510 (the first version without the sub25 connnectors).
Could it be that i overheated the Pad switch when soldering it in or reflowing the solder joints?

Unlikely. I would honestly try another rack especially if you have an early version. Many reports of similar behavior with those racks and a few other Asian models.

 

[haselnusse]

Thanks, i tried the Pre in different slots of that same rack but will try to get my hands on another rack to try them in. Cheers for all the help!

 

[Mole-man]

Hello,

I recently purchased an unused vp312 rev a kit second hand and it's missing resistor R9. Can any resistors with the same spec (160r, 1%tolerance, 0.25watt,metal film) be used?

Thanks.

 

[[silent:arts]]

Yes  8)

 

[Potato Cakes]

Thanks for the fast answer!
It is a Lindell 510 (the first version without the sub25 connnectors).
Could it be that i overheated the Pad switch when soldering it in or reflowing the solder joints?

I had a Lindell 510 (first version) and it would power some pres but not others and had trouble with most compressors. I contacted my gear dealer and sent mine back and they sent me a new one with an external power supply. My recommendation would be to get it swapped out. I think they will just do it since that first design is plagued by a bad power scheme.

Thanks!

Paul

 

[Mole-man]

Hello,

I accidentally soldered the bourns t-pad too close to the board. I have managed to re-soldered and get it into the correct position but am wondering whether all the soldering may have overheated it and caused some damage..
Should I complete the rest of the build and test it or could a faulty t-pad cause damage to other components?

Thanks in advance

 

[[silent:arts]]

A broken T-Pad won't damage anything.

 

[Mrosso]

I have just finished one of two VP312DI pres for 24V 51X. The pre seems to be functioning  as expected; however, the phantom LED is not working. The first time I fired up the pre and flipped the switch for +48V, the LED flashed for a second then went dark. The phantom power is working, but the LED is dark. Double-checked polarity. Is there anything special about the LED contained in the kit? I used a generic old red LED I had laying around instead. Shouldn't all  3mmred LED be same specs?