Short circuit?

[BladeSG]

How does one go about finding the source of a short (without physically changing all componenets one by one) when:

1. You know that 30V AC is coming into the rectifier (w04) but +6VDC and -25VDC coming out.
2. You've replaced the rectifier and regulators and there is no change.
3. There is +6VDC after a 7815 and -14.8VDC after a 7915.
4. There is not visually any shorts on component side and trace side of PCB.
5. You have already re-soldered virtually every point.

If this is a stupid question, feel free to flame me.

Thanks,

Steve.

 

[gyraf]

Cut the pcb traces at various stratetic places, and resolder with a piece of wire afterwards..

 

[PRR]

Sounds like you are missing the center-tap and also the capacitors.

 

[Svart]

if you remove everything after the bridge does it stay the same? usually if a Vreg has lost it's ground sense the output will float to whatever the input is.

 

[BladeSG]

Thank you all.

I tried the light trick and it revealed nothing (good idea though). The caps are in correctly too.

@PRR- In regards to 'Center-Tap' I'm not 100% sure what you mean. On toroid (jaycar MT2086 15+15 20VA):

There is Yellow(0V)/Red(+V) and White(0V)/Purple(+V), so I tied the Red and White together then used the Purple and Yellow directly to the PCB. Earth is wired directly to the IEC power connector. There is approx. 30-32VAC coming in the rectifier.

Cutting PCB traces will have to be a last resort.

Thanks again guys. it's much appreciated.

 

[gyraf]

[quote author="BladeSG"] There is Yellow(0V)/Red(+V) and White(0V)/Purple(+V), so I tied the Red and White together then used the Purple and Yellow directly to the PCB. Earth is wired directly to the IEC power connector. There is approx. 30-32VAC coming in the rectifier.[/quote]

So what you're saying is that your red+white does not go to the PCB?

They should - they are our 0V transformer reference.

This is why there is three points for the transformer connection: 15-0-15V AC.

Jakob E.

 

[Guest]

[quote author="gyraf"][quote author="BladeSG"] There is Yellow(0V)/Red(+V) and White(0V)/Purple(+V), so I tied the Red and White together then used the Purple and Yellow directly to the PCB. Earth is wired directly to the IEC power connector. There is approx. 30-32VAC coming in the rectifier.[/quote]

So what you're saying is that your red+white does not go to the PCB?

They should - they are our 0V transformer reference.

This is why there is three points for the transformer connection: 15-0-15V AC.

Jakob E.[/quote]
Yep - it seems from my very limited experience that you need the following into the three headers on the pcb
Assuming we are talking about the secondary and not the primary....

red
white and yellow
purple

BTW I am building this right at the moment....
(self etch with etch resistant pen) - with 4 sets of outputs

 

[BladeSG]

[quote author="gyraf"]

So what you're saying is that your red+white does not go to the PCB?

They should - they are our 0V transformer reference.

This is why there is three points for the transformer connection: 15-0-15V AC.

Jakob E.[/quote]

Oh My God! I'm so unashamedly embarressed at this point, but at the same time I'm so delighted to finally have my GSSL Clone work, and work it does beautifully without any apparent problem.

Thank you Jakob especially for your patience with a noob like me, and PRR for leading me to this 'centre tap' thing. All you guys rock!

I admit that I would have never known it was necessary to connect these tied wires to the middle input. A friend helped me with this part (toroid wiring) and I asumed what he told me was correct as he's very qualified in a closely related profession, although I remember him questioning something about the ground trace on the GSSL PCB's.

Thanks again all of you who took the time to help, I appreciate it and hope that one day I'll be in a position to be able to do the same for you.

Steve.

 

[PRR]

> unashamedly embarrassed at this point... I would have never known it was necessary to connect these tied wires to the middle input. A friend helped me with this part (toroid wiring) and I assumed what he told me was correct as he's very qualified in a closely related profession

Do not be embarrassed! This stuff is not obvious. Even to someone who has wired other types of power supplies before.