Salas hotrodded blue DCB1 build

[Erlend Sæterdal]

Power supply voltage

My B 1 with Salas Shunt have only 10 V out with 21 V in is this ok ? As well I thought it will be hot added big heatsinks. I can not feel any temperature rise at all !

 

[schubert]

What kind of thermometer should be used to measure the temperature of the mosfet tabs? I tried a digital lab thermometer, but I guess they really don't work unless they're immersed in liquid.

 

[Renron]

Infra-Red gun.
Like this one. You'll find lots of other uses for one too.
Ron

 

[schubert]

Thanks - ordered one.

 

[suburra]

Hi Salas
I have a problem on my DCB1

I have just swap the output capacitors, before Elna Cerafine and now Nichicon ES

But now don't work: relè click, all led light up but the quintuplet, negative and positive

Could you help me?

Thank you

Marco

p.s. I'm on the way for shunt SIT

 

[Salas]

Meaning the 100uF output capacitors? I would fit the others back to check if the bipolars created some obscure issue.

 

[suburra]

Salas

Yes, are two 100uF output caps

Ok.. return to cerafine and report

Thanks for reply.

 

[suburra]

Salas

No good news...

I tried to return to Cerafine but, like before, the 2 strigs of 5leds don't light up...

Before swapping the capacitors, my DCB1 was perfect.

Maybe for desolder the Capacitors, can too much hot have damage some transistors?


Thanks in advance to everyone can help me.

Marco

 

[AndrewT]

broken trace or shorted traces.

 

[suburra]

AndrewT,

I have looked many times the PCB

No shorted or broken traces

Thanks for reply

Marco

 

[Salas]

There is no reason losing the Vref for just tasting termination capacitors. Some mishap must have occurred during ''operations''. See if the JFETs at the 5 LEDS tails are intact also. Is your iron showing ~0 Ohm from tip to its mains earth prong? Is it static safe in other words? Check for live Vbe, Vgs, everything semi.

 

[suburra]

Salas

My solder station it's "static safe"
I'll check all the semiconductors and report

many thanks

Marco

ps

the 2 mosfets near 100uF capacitors, remain cool by turning on the unit...

 

[Salas]

See if they show Vgs.

 

[jeff517]

OK folks, I'm ready to put some power to this thing. I have an ANTEK 50Va by 12v x 2 torroidal transformer. 2 red, 2 black and 1 purple wires on 120v side. And 2 green and 2 blue wires on 12v side. Do I wire mains(120 side) in parallel, and same on 12v side?
Too many wires and I would really like to not toast this board up.Suggestions?

 

[jeff517]

http://www.antekinc.com/pdf/AS-0512.pdf

This is what the manufacturer s site has as far as help.

 

[Salas]

Secondaries to DCB1's transformer connector marked AC IN as shown. Primaries in parallel for USA mains. Purple magnetic shield wire bolts with the mains ground wire to chassis.

 

[AndrewT]

and use a bulb tester for the power up.

 

[jeff517]

Thank you all for your patience and help.

 

[atupi]

I want to install my DCB1 buffer into a metal case. It's ok to connect the case to the GND of pcb ? I'm using isolated RCA connectors.

 

[boywonder]

A couple more newbie DCB1 questions.......

My DCB1 is working fine, but I have a few questions.....

I'm running 10 ohm R's (200ma config) with two separate 60VA 12V single secondary transformers (so 120VA total). My DC output voltages are +10.04 and -10.11 and the unloaded transformer voltages are about 13.2VDC. I understand that for most of the various hot rod configs at least 15VDC/50VA is recommended. How do I test/verify that I have enough voltage headroom with my transformers? Should I measure the DC output voltage stability with a 5K or 10K load on the outputs at full input signal?

I'm also measuring 2V across the 10R on the IRFP240 side and 1.75V across the 10R on the 9240 side, so 200ma and 175ma. I understand this is the quiescent current for the shunt part of the PS.

Is it normal to have 25ma different between the + and - sides? I am assuming that it is, and is probably no big deal.