[BUILD] CAPI VC528 ML2~500 Series~Missing Link 2~Official Support Thread

[jsteiger]

I have built six of these. Four work great, but two have low/sputtery output. Is there a good spot I should start looking at?

Opamps and/or the discrete followers.

 

[abeLovesDIY]

Thank you so much. All are healthy now except one. The green active LED is always on. The red bypass doesn't light, even when in that mode. The audio definitely does. Is this bad relay? Or a component to check in between that path? Thanks so much for the assistance!

 

[jsteiger]

Thank you so much. All are healthy now except one. The green active LED is always on. The red bypass doesn't light, even when in that mode. The audio definitely does. Is this bad relay? Or a component to check in between that path? Thanks so much for the assistance!

Backwards red LED or backwards diode right near those 2 LEDs.

 

[abeLovesDIY]

Backwards red LED or backwards diode right near those 2 LEDs.

Thanks Jeff. The Red LED was reversed. Fixed now - thanks so much!

 

[abeLovesDIY]

The tip of one of the WP13GD Green LEDs is chipped off. Not the end of the world, but was wondering if anyone knows of a reasonable source? Mouser is non-stocked, and eBay is asking $16+15 shipping for a single one.

 

[abeLovesDIY]

For anyone else - I found these: 2mm Tower Diffused Pure Green LED - Ultra Bright -

 

[abeLovesDIY]

@jsteiger hanks so much for all your help. My last unit is working great after your LED tip, but for some reason the nut stripped the grayhill Trim switch on this one. Is there any secret trick to make the threading usable when this happens? Or do I need to buy another switch, desolder, and be more careful? I usually just finger tight and then give it a rotation or two so that nothing moves, not sure how it stripped tbqh.

 

[andYz00m]

Checking the site everyday in hopes that somehow these will be available soon.

 

[Siegfried Meier]

Hey all! I have 2 of these sitting on the bench, appearing to work perfectly. The manual for the CMRR calibration seems to be rather outdated. Is there a new method, or simpler method maybe, for the current revision of boards? I'm eager to hear these!

 

[andYz00m]

Hey all! I have 2 of these sitting on the bench, appearing to work perfectly. The manual for the CMRR calibration seems to be rather outdated. Is there a new method, or simpler method maybe, for the current revision of boards? I'm eager to hear these!

Agreed. I found the ST2 instructions which add some more detail but there isn’t a description of which test point to use for the Rev B.3. The old instructions suggest the output of C3?

I’m using the extension jig.

 

[hasanova]

Agreed. I found the ST2 instructions which add some more detail but there isn’t a description of which test point to use for the Rev B.3. The old instructions suggest the output of C3?

I’m using the extension jig.

Yes, I also highly recommend the extension jig with the CMRR switch. Otherwise build your own "calibration cable" like chunger (see post #65). With the jig you can ignore the other connections in the support docs (they are for this special cable) and just make your normal audio connections (instructions are written on the jig PCB).


You'll find in the support doc's, at the very end of the VC528 ML2 assembly aid Rev_1 [Last upload 9/19/2015]:
**Final Adjustments**
3. For the CMRR adjustment of RV1, refer to the directions on the Extension Jig. Your output
monitoring connections should be made as shown in the following pic.

It's the same connections on Rev B.3 (negative side of C7 and GND) for output monitoring (VAC with DMM).



Also, search on the support docs page for "CMRR". You'll find this pdf:
VC528 CMRR Adjustment. Follow these instructions (along with the ext. jig if you have one) for the trimmer adjustment.

Cheers!

 

[andYz00m]

Yes, I also highly recommend the extension jig with the CMRR switch. Otherwise build your own "calibration cable" like chunger (see post #65). With the jig you can ignore the other connections in the support docs (they are for this special cable) and just make your normal audio connections (instructions are written on the jig PCB).
View attachment 119278

You'll find in the support doc's, at the very end of the VC528 ML2 assembly aid Rev_1 [Last upload 9/19/2015]:
**Final Adjustments**
3. For the CMRR adjustment of RV1, refer to the directions on the Extension Jig. Your output
monitoring connections should be made as shown in the following pic.

It's the same connections on Rev B.3 (negative side of C7 and GND) for output monitoring (VAC with DMM).

View attachment 119274

Also, search on the support docs page for "CMRR". You'll find this pdf:
VC528 CMRR Adjustment. Follow these instructions (along with the ext. jig if you have one) for the trimmer adjustment.

Cheers!

Yep! After much hurumphing, found these very same docs!

Thank you.

 

[andYz00m]

Got both my units built and calibrated. Sounding great!!

How does the DC link work on these? Do I set the jumper to link and then use the "Stereo" setting on my 500 rack? What elements are linked? Im trying to find in the docs where it mentions something but I think I read that it's just the bypass/active setting that is linked.

Thanks!