Potato Cakes

Re: [BUILD] CAPI VP28~500 Series~2-Stage Preamp~Official Support Thread
« Reply #1040 on: April 15, 2019, 11:12:35 PM »
I have been combing through the thread to see if anyone had similar issues but I can't seem to find anything.  My VP28 build does not seem to be passing any signal.

I'm pretty sure that on this thread and most all the other build threads here on the GDIY forum there are several posts about builds not passing signal. Also, just saying it is not passing signal is not going to be useful in diagnosing the problem. Unfortunately you will have to go back through this thread a little more closely and read all the posts on this thread regarding op amps, solder joints, transformers, etc. There are also voltages posted for the test points on VP28 Support page on the CAPI website to aid in troubleshooting. I know it doesn't sound like fun, but trying to find errors in one's build rarely is.

Thanks!

Paul


jsteiger

Re: [BUILD] CAPI VP28~500 Series~2-Stage Preamp~Official Support Thread
« Reply #1041 on: April 16, 2019, 12:13:56 AM »
Hello All,

I have been combing through the thread to see if anyone had similar issues but I can't seem to find anything.  My VP28 build does not seem to be passing any signal. The green LED does not light up and there seems to be nothing passing through. The other LEDs are working and everything seems to look fine but not sure where to start. Does anyone have any suggestions on where to look first? Thanks!
As always, please tell us first about the opamps. What are they and who built them?

Also, have you tried the Test Points doc? Where does your module stop showing the same results as what is posted in the TP doc?

As Paul mentioned, read back thru this thread and you will find a plethora of excellent info for you to at least start with.
« Last Edit: April 16, 2019, 12:17:11 AM by jsteiger »
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resilient

Re: [BUILD] CAPI VP28~500 Series~2-Stage Preamp~Official Support Thread
« Reply #1042 on: April 16, 2019, 09:13:24 AM »
Did you also build your opamps?

You will want to get known working on amps to start with.

Brandon

Re: [BUILD] CAPI VP28~500 Series~2-Stage Preamp~Official Support Thread
« Reply #1043 on: April 19, 2019, 01:57:01 PM »
Did I said that already CAPI freakin' ROCK 8) 8) 8) 8) 8) 8) 8) . Building new one today and yes having working op-amp to test with is a must, but also if you start building lots, it may be worthed to have the FiveFish test JIG or even better check this thread
https://groupdiy.com/index.php?topic=60558.0
« Last Edit: April 19, 2019, 02:03:33 PM by noiro »

Leon

burnt PR1&PR3 after putting in a newly built DOA
« Reply #1044 on: May 29, 2019, 12:40:28 PM »
My VP28 has been working great. Today I used it to test a newly built GAR2520. It did not passing signals, and I smelled something. Well looks like PR1 and PR3 got burnt (see pictures). Any idea what  could be wrong with the GAR2520? I did check the critical points mentioned in the guide botg virtually and using multi meter. There is no short.  Any help will be greatly appreciated!

Leon

Re: [BUILD] CAPI VP28~500 Series~2-Stage Preamp~Official Support Thread
« Reply #1045 on: May 29, 2019, 12:42:09 PM »
Here is a photo of the DOA

Leon

Re: [BUILD] CAPI VP28~500 Series~2-Stage Preamp~Official Support Thread
« Reply #1046 on: May 29, 2019, 12:43:23 PM »
bottom side of the DOA:

Leon

Re: [BUILD] CAPI VP28~500 Series~2-Stage Preamp~Official Support Thread
« Reply #1047 on: May 29, 2019, 01:14:10 PM »
Just saw it in the GAR2520 thread, I switched BD138, BD140, thinking they are the same. Making mistakes at the very end has become a habit to me . Too bad    :(

TillM

Re: [BUILD] CAPI VP28~500 Series~2-Stage Preamp~Official Support Thread
« Reply #1048 on: May 29, 2019, 01:36:21 PM »
No worries,
This can happen.
Just change the burned resistors and swap the BD139 with the BD140 and everything will work.

Leon

Re: [BUILD] CAPI VP28~500 Series~2-Stage Preamp~Official Support Thread
« Reply #1049 on: May 29, 2019, 07:10:29 PM »
No worries,
This can happen.
Just change the burned resistors and swap the BD139 with the BD140 and everything will work.
Yeah, just did that and now it works again. Thanks!


 

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