goldenreference low voltage power supply

[kevin gilmore]

i don't remember ever picking elna caps, definitely did pick the wima caps

will look when i get home

[Pars]

Can't remember who posted the original BOM, don't think it was you.
The Wima are pretty much the only ones that large cap in that small of footprint.


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[Tinkerer]

Thought I would build my spare GRLV board and transformer into a 12VDC PSU for the little STAX amp. What value do I need for the R8/R9?

Edited April 1, 2017 by Tinkerer

[kevin gilmore]

I have never tried to get it to work that low, highly likely you have to use the 7V reference chip. Then it should work

[Kerry]

Just built my mini GRLV supplies.  The Negative came up just fine and works perfectly

The positive supply is giving me some issues and I'll need to debug it.

Here's some pictures...

 

This pic shows a board I made for the Blue Hawaii that has the +5V, Digital Controller (ATMega328P) and Digital attenuator board along with the GR7/9xx regulators.  I'll mount them once the positive supply is working.

[JoaMat]

Wow, very nice!

[gepardcv]

What is the heatsinking story with these mini-GRLVs?

[congo5]

1 hour ago, gepardcv said:

What is the heatsinking story with these mini-GRLVs?

For low amperage/wattage like in pic above, copper on the board is the heatsink

for higher power you can mount it to whatever size heatsink it needs.

[gepardcv]

Well, I finally got around to making a GRLV. Three of them, actually. The positive rail works fine on all three, outputs perfect voltages (one +20V, two +30V, exactly as expected). The negative rail on all three outputs 0V. What's a good place in the circuit to start digging?

[mwl168]

Can you post a close up photo of the negative side?  

[congo5]

what is voltage of collector on MJW21193?

and base?

emitter?

[gepardcv]

On MJW21193, emitter voltage is 0, collector 0.117V, base 0.012V. Picture attached. I'm using a center-tapped transformer winding, so just one bridge.

[spritzer]

I assume there is a trace to connect the second output from the rectifier so what is the raw DC on the input cap?

[congo5]

The main storage cap connects directly to bridge rectifier and collector so .1v

bad bridge or no connection to transformer?

That board is nice and clean!

What is ACV at terminal block?

the voltage is not making it through the first two inches............

[spritzer]

Hehe didn't read what was above the pic...   Yeah has to be a bad  connection...

[congo5]

just stating fact, the best I know, not to infer anything

there should be continuity between collector and pin of bridge closest to input connector

and second pin of rectifier to transformer input

a dead short like a bad cap would make the transformer unhappy, buzz and hot. I assume that isn't the case.

usually its a very simple cause, but hard enough when its in front of you to find.

I have one that is a bit noisy, like 5v of ripple at 80hz, I did the layout so you know where the problem stems from.

 

[Tinkerer]

Probably the trace on the top of the board for the bridge, that last leg closest to the AC input.

[gepardcv]

Interesting! I'm measuring no continuity between the collector of the MJW21193 and the bridge leg closest to the AC input. Would that explain it? In which case I guess I should just jumper those two points?

[cspirou]

Since it's all three I would say it's a bad PCB?

[kevin gilmore]

highly unlikely the board is bad

maybe you are connecting the transformer to the wrong place, center tap of transformer goes to the middle pin and for single bridge the other 2 wires go next to the center pin

if there is no raw dc voltage on either of the main power caps, the bridge is toast or not the correct type for this board

[congo5]

transformer input vac? blue to pink, and each to green? (center three)

brown trace connects though via on right bridge footprint?

 

7 hours ago, gepardcv said:

In which case I guess I should just jumper those two points?

Lets find out where the break is first.

is it just the via? that is easy to fix.

Edited April 8, 2017 by congo5

[congo5]

when using single bridge it seems like a good idea to solder a wire in that one hole

rather than rely on the through hole plating

[Tinkerer]

The problem with the single bridge on my boards (blue ones from the last GB) was the holes were smaller than the side ones so you had to drill it out to fit. I left the bridge lifted up a bit from the board so I could solder that top board trace from the top side to be sure it was connected right.

[kevin gilmore]

why no one tell me I got the wrong hole size...

updated goldenreference6d file.

[Pars]

It was mentioned in the group buy thread, but not here. Our bad