Building a symmetrical PSU B1 buffer

[woodturner-fran]

Was there not a checklist posted back up a bit that told you what to check at power up? Things like the voltage across the 68//68 and so on?

Merlin: yes, all the LEDs should be lit, and you should be able to notice the power fets getting warm. The relay should click. Did you solder in the jumpers?

Oh, and post some pics, it might really help. Topside and bottomside and a pic in its case if you have got that far.

Visit this post for a pretty clear view of the board, helpful in checking orientation:

http://www.diyaudio.com/forums/pass...symmetrical-psu-b1-buffer-82.html#post2043290


Fran

 

[merlin2069er]

Ok, I put some leds in my other board and got a bit better results.

I'm getting 8.77v and -6.17v @ the center position.

I got half the leds lit up on this board. I guess I got some in backwards.

The short leg on the led is the cathod right and it should face that way |) ?

Where is that checklist, that would be helpful.

 

[merlin2069er]

Oh, one other thing , should I be using 1 pair of transformer outputs for 12vac or combine them for 24vac into the dbc1?

 

[Salas]

The short lead on the flat rim side is the cathode. There is a [) symbol on the boards for each row's orientation. Just put the dark ones the same way you put the lit ones in their respective rows. Have you got lit ones in all rows?

You need 3 AC leads. 12-0-12. What exactly you have there now? Can you take a picture?

 

[merlin2069er]

I got 50% lit. Should I just flip the unlit ones around?

 

[Salas]

Check the flat rim sides first. Are they opposite to the neighboring lit ones? If yes, turn the dark ones around. But I am mainly afraid you did something wrong with the Tx wiring.

 

[merlin2069er]

Great, I got one working. I get ~10v at the center points, and I heard the relay click over.

 

[Salas]

Good. What was the problem?

 

[merlin2069er]

Hmm, maybe a cold solder joint. I just reset the 3 leds that were off.

Also, I'm using 24vac into the dcb1.

The other unit is a bit odd. The bottom leds light up then fade off after 30 seconds. I've check the orientation of the leds and transistors they all look correct.

 

[Salas]

Are your diodes in the same way as on the one that lights up? You need a center tap. 12-0-12.

 

[merlin2069er]

Ok, maybe I should wire up the centre tap.

 

[merlin2069er]

Connecting the center tap fixed the leds from fading.

But the top 8 leds are still off. What else could it be?

 

[Salas]

Either are all wrong way, check cathodes, or something had failed in your tests before. Start from the bridge diodes. Also see if you miss a jumper.

 

[merlin2069er]

Ok, thanks for your help. I'll give that a try tomorrow.

Where is the latest schematic. I've got the original (from post#1).

 

[sutantoroy]

Mine was also dying once after several periode changing 68//68 into 10 R. The problem was one of the IRFP9240 is gone unnormal AKA died

 

[merlin2069er]

I got all 4 of my dcb1 powered up and working.

I'm now shopping for 4x cases.

Any suggestions?

 

[merlin2069er]

Mine was also dying once after several periode changing 68//68 into 10 R. The problem was one of the IRFP9240 is gone unnormal AKA died

The top leds died on me again. How did you figure out that the IRFP9240 died on you?

 

[AndrewT]

Hi,
measure the Drain to Source voltage when powered.
Measure the Drain to Source resistance, in both directions, when fully discharged after power off.

 

[merlin2069er]

Ok, I figured it out. One side of the 3 leds pads lifted off the board, and wasn't making contact with the ground pin of the k170. I wired in a jumper.

All ok now!

 

[udailey]

Good trouble shooting Joe. So when do you listen!?