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

[Reverend]

Ok. Thanks Jeff. However, in the zip file I was sent, the old relay board layout was sent with R1 in the top left corner. I didn't get a layout that had Q1 in the top left like my newer version. Sorry.

No matter as the part values and numbers are the same for both versions of the PCB. The circuit did not change.

Jeff, Sorry to be such a bother. Don't kill me - you were right. Good news. I've found something wrong with the relay. I had the caps swapped. 18uF where 10uF should have been. I tried to pull them out and swap them back, but now, since it was so hard getting this relay out, I'm sure it's best to just get a new relay. Just to make sure....(I'm building the VP312DI 500 series version NOT the 51x version. So I need the 12V version of the relay - correct?

 

[jsteiger]

Yes. The 12V relay kit is used for either VPR or 51x. There must be something more than the caps. It would still work with those 2 caps swapped. Check to make sure the 4V3 zener is in the correct way and position.

 

[Reverend]

Yes. The 12V relay kit is used for either VPR or 51x. There must be something more than the caps. It would still work with those 2 caps swapped. Check to make sure the 4V3 zener is in the correct way and position.

Ok. I got the new relay and built it really, really slowly and meticulously. I bought a new JJ1731 op amp (I would have bought a GAR2520 from you, but I don't think you've got them right now). I built a BB2521 very, very slowly.
I've still got the same thing, the output attenuator brings up hiss and the preamp gain does the same thing except there's a little bit of fuzz oscillation when I twist that knob.
I keep turning the power off, unplugging the power and switching the op-amps between the tested 1731 and the BB2521 and its all the same. New relay in the main PCB position (the caps and all are right in the relay next to the DI section of the pcb.
I'm going to send a couple of pictures and make another post. Thanks for walking me through this. Please be on the lookout for the pictures.

 

[Reverend]

Is J1-1 in right?

 

[jsteiger]

Is J1-1 in right?

Yes you want the output coupling caps in the circuit to protect the 2503 from DC.

 

[Reverend]

I've ruled out the op-amp, the relay, J1-1, and checked the whole pcb upside and down. I've got a test jig so I can test it on the bench, but I don't know how to do it/where to start. Can someone help me figure this out? Thanks.

 

[jsteiger]

You will need to inject a test tone sine wave and follow the signal thru the pre using the schematic as a "road map". There are a number of helpful post around the site here describing the process.

 

[Reverend]

Jeff, You were right. It was a relay board. It was the one near the DI stage. I found two solder joints that were touching while inspecting with a magnifying headband.  I got the headband AFTER I soldered the relay boards, and I feel certain that I wouldn't have made the mistake if I had them through the whole project. I think it would sure help other newbies like me to work with the headband magnifier.
Anyway, I got it working and the use of the extension jig came in really handy and is great for testing my other 500 series units.
The 312DI sounds awesome and thick. I can't wait to use it on my next project which is going to be cranking up very soon.
Thanks so much for putting up with me. Now I've got to decide what the next project is.

 

[jsteiger]

No worries Reverend, I am glad you found it! Congrats 

 

[prh]

Just a suggestion (which works for me)...

Working with the schematic, a continuity tester can be really helpful in finding solder bridges. 

 

[Reverend]

Just a suggestion (which works for me)...

Working with the schematic, a continuity tester can be really helpful in finding solder bridges.

PRH, I found the solder bridge looking through the magnifying headband, but I had the schematic out with a test tone and my DMM, but I'm such a newbie, I really didn't know how to do it. Can you recommend a YouTube or website that may help me learn how to use the tester with the schematic? Thanks. Hope that this isn't too off topic.

 

[rainton]

I tried to find some info here on this already but had no luck and also sent a message through the capi website but
had no reply so far.

I want to build two of the VP 312DI in 1U rack with my own front panels

What is the best way to add a LED-Peakmeter like this one here :
http://sound.westhost.com/project60.htm

to the circuit to monitor the input stage?

Or maybe a clipping LED circuit that features a multi-color LED that gives me SIGNAL (green) and CLIPPING (red)

Thanks for any advice!

 

[bugbrand]

Sorry for the bump, but I wondered if anyone could quickly answer::::

Are Classic API kits (in particular the VP312DI which I just received) RoHS / Lead-free compliant?
I ask because I could use leaded solder, but do 99.9% of my work lead-free.

Sorry if I missed this info anywhere...

Thanks! Tom

 

[jsteiger]

Sorry for the bump, but I wondered if anyone could quickly answer::::

Are Classic API kits (in particular the VP312DI which I just received) RoHS / Lead-free compliant?
I ask because I could use leaded solder, but do 99.9% of my work lead-free.

Sorry if I missed this info anywhere...

Thanks! Tom

The majority of the items are RoHS compliant but not everything. You can solder them however you want.

 

[bugbrand]

Thanks Jeff - it is not that I need to comply with RoHS, more that I'd prefer to use my regular lead-free approach.

So, let's change the focus to lead-free rather than RoHS -- Leaded solder is OK on lead-free, but lead-free is not good on leaded parts. So, I'd like to try to be as sure as possible before beginning the build.

Of course, I thought some more and presumed most parts would be lead-free - checked some Mouser parts etc and of course the PCBs/DOA-pins/etc. are gold finish. Most parts these days are RoHS, anyways..

Well, I'll see how it goes - will check with BOMs and part codes.

Thanks, Tom

 

[jsteiger]

Thanks Jeff - it is not that I need to comply with RoHS, more that I'd prefer to use my regular lead-free approach.

So, let's change the focus to lead-free rather than RoHS -- Leaded solder is OK on lead-free, but lead-free is not good on leaded parts. So, I'd like to try to be as sure as possible before beginning the build.

Of course, I thought some more and presumed most parts would be lead-free - checked some Mouser parts etc and of course the PCBs/DOA-pins/etc. are gold finish. Most parts these days are RoHS, anyways..

Well, I'll see how it goes - will check with BOMs and part codes.

Thanks, Tom

Let us know how you do Tom. Since I am not shipping assembled modules, I don't worry as much about it.

 

[bugbrand]

Well, quick run through the VP312DI rev.c.1 Main BOM - all parts come back as RoHS except 3 unsearchables - the 2 EA transformers and the Bourns TPad (though the other Bourns is RoHS).
It'd be interesting to know on the transformers, but otherwise it sure is looking likely that all is fine lead-free.
Thanks Jeff!

 

[bugbrand]

Fine going on the main unit - nice kit, for sure!

But, on to the DOAs [got a GAR1731 & a GAR2520 kit] - these have PCBs without AU surface finish, so.. Jeff, I presume you get these made yourself? Can you tell me what surface finish you use for these? [HASL or HASL RoHS - I always presume 'regular' HASL would be tin/lead]. Anyway, going to stop work now until I'm back at the workshop tomorrow [where I can make them with leaded solder..]


One minor notice - CAP C10 was provided as 6.3V rather than spec'd 16V [from the BOM] - 6.3V seems perhaps low?

Also, haven't yet found a detail mention on optional R3 [sorry, didn't get through the 2nd half of this thread *yet*] - marked optional on BOM, and I see it on the schem.. . Hmm..


Thanks!

 

[jsteiger]

Fine going on the main unit - nice kit, for sure!

But, on to the DOAs [got a GAR1731 & a GAR2520 kit] - these have PCBs without AU surface finish, so.. Jeff, I presume you get these made yourself? Can you tell me what surface finish you use for these? [HASL or HASL RoHS - I always presume 'regular' HASL would be tin/lead]. Anyway, going to stop work now until I'm back at the workshop tomorrow [where I can make them with leaded solder..]


One minor notice - CAP C10 was provided as 6.3V rather than spec'd 16V [from the BOM] - 6.3V seems perhaps low?

Also, haven't yet found a detail mention on optional R3 [sorry, didn't get through the 2nd half of this thread *yet*] - marked optional on BOM, and I see it on the schem.. . Hmm..


Thanks!

Gary supplies me with the gar1731 and gar2520 kits so I can't answer that question. Maybe post on their respective build threads?

That 470µF cap should never see more than 1V DC on it and that is only if the pre is in post 2622 DI mode. Under typical conditions it will be more like 100mV or a little less. If it is more than that, there is a series problem somewhere else!

R3 is the 150k load R. This will slightly lower the  input Z of the preamp. Leaving it out tends to yield a slightly more "open" sound. I usually build 312's without it.

 

[bugbrand]

Thanks for replying so quickly Jeff. That clears up the 2 points nicely then - thanks.

Started busting through the rest of the thread & saw about the GAR build threads so, yes, will ask there.