Gainclone building contest details (from BrianGT group order)

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ble0t said:
This thing still going on or no? Can we extend it? I just need 2 or 3 more days till I get mine pretty much done 🙂

Yes, it is.

For those who have sent me pictures, which are in my gallery, and haven't received their free pcb set, drop me an e-mail to: brian-orders@darg.net with the subject "Contest PCB" along with your address. I have a hard time associating the user names with the address information in my database.

I have a stack of pcbs waiting to go out.

--
Brian
 
Rail E at output

Sorry for the delay, I have been busy. Here's a pic of my first attempt at a non-inverted gain clone(NIGC). Since it shows only negative supply rail at the outputs, it's a non-working, non-inverted gain clone (NWNIGC) :xeye: Any suggestions appreciated.

Thanks in Advance

Jimbo
 

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- supply at both outputs or just one? i had a resistor that lost some paint and became conductive between pin 3 and 4....speaker out and - rail. 🙁 did you check power from the power supply to make sure the + and - rails were there?

-Matthew K. Olson
 
Re: Rail E at output

jimbo149 said:
Sorry for the delay, I have been busy. Here's a pic of my first attempt at a non-inverted gain clone(NIGC). Since it shows only negative supply rail at the outputs, it's a non-working, non-inverted gain clone (NWNIGC) :xeye: Any suggestions appreciated.

Thanks in Advance

Jimbo

Since you are using a normal bridge rectifier, and not the dual bridge setup, you should only have 1 gnd wire going to the pcb from your transformer center-tap/chassis gnd.

Here is an alternate setup for you to try:
----------------------------------------
IN/SGND - to rca
OUT/OG - to binding posts
+V/-V - to power supply rails
CHG - chassis gnd, tie this to your central ground

That should be all that you need to use, with the rest of your grounds from your transformer, and AC GND going to a central ground in your case.

Give that a try. I suspect that you might have a gnd loop now, or something strange going on.

--
Brian
 
bit of an overkill with those heatsinks

Agreed, but the price was right ~ FREE. Cut in half they were two small, i.e., not tall enough. Anyway, I have a little honey pot of heatsinks in a stash. You'll be seeing those again.

sleeving over those exposed mains connections for safety's sake!

The only exposed items are the bottom of the fuse connector and the solder joints on the DPDT switch. Otherwise, all covered.

The pot arrived without the requisite unobtainium 9MM x .7??? nut. So thus and so, find an alternative. I will be attaching a knob/rod/silastic tube to the pot shaft that will pass through the oilite bush on the front panel.
 
Everything checks out perfectly; no bridges, cold joints, all component values correct and in the correct holes, PS voltages correct. Still -22V at outputs. I tired of the project and scrapped the boards this afternoon. I'll try again with no boards next time, the transformers and bridges work just fine.

Jimbo
 
Re: Re: Rail E at output

BrianGT said:


Here is an alternate setup for you to try:
----------------------------------------

CHG - chassis gnd, tie this to your central ground

That should be all that you need to use, with the rest of your grounds from your transformer, and AC GND going to a central ground in your case.

Give that a try. I suspect that you might have a gnd loop now, or something strange going on.

--
Brian


Jimbo, sorry to hear about your problem.
Did you try Brain's suggestions? From you picture you have the CHG to your RCA input ground that may cause you problems..

Chris

Or have you try doing one channel only first? Try one transformer, one bridge rectifier and one BrainGT board to see if you have problems?
 
I made a bit pof a marathon of it on Sunday, trying every possible way to ground the boards, starting with Brian's suggestions; even RCA grounds lifted. The result was unwavering -22V at output. Each channel is(was) powered by its own seperate xformer and bridge.

Jimbo
 
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