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SST03 troubleshooting

Started by Maarten Stevens, April 13, 2012, 05:18:55 PM

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peranders

I'l loosing track here. Can you measure once again please.

R10 and all transistors.
/Per-Anders Sjöström, owner of this forum

Homepage with my DIY hifi stuff

Maarten Stevens

I will post the schematic with all the voltages later... this should help I hope to identify the problem...

Maarten Stevens

Hi Peranders.
I have written down all voltages, and identified the fault. Voltage between D2 and D3 was 32V (good), voltage between D3 and Q1 was -0.4V. Hence I guessed there was something wrong with the caps. So I removed C4 and C5 and it worked.

Unfortunately, I am not sure if I am where I want to be.... I get a blown fuse now upon startup with transformer and PSU....  :?

peranders

Do you get a delay now? Have you replaced the caps which must be made of polyester?
/Per-Anders Sjöström, owner of this forum

Homepage with my DIY hifi stuff

Maarten Stevens

I think it is delayed (I hear c-click I think). The caps I had in were 1uF 63V WIMA....

peranders

Quote from: Maarten Stevens on April 16, 2012, 10:09:38 PM
I get a blown fuse now upon startup with transformer and PSU....  :?
What kind of fuse, rating? Fast, slow?
Transformer size?
/Per-Anders Sjöström, owner of this forum

Homepage with my DIY hifi stuff

Maarten Stevens

Hei Per Anders,
I was using a 1.25 slowblow, which blew all the time. I have now replaced for a 2A and it works now. The transformer is 400VA.

I am still running without C4 and C5 positions filled, what is the impact of that? How can I insert a suitable cap here?

Also I see sometimes a little spark around the relays... this doesnt seem to affect it though, as no fuse is blown, and the psu starts up normally. What can this be?

Thanks,
Maarten

peranders

The 1 uF caps are there for creating a delay - a soft start.
/Per-Anders Sjöström, owner of this forum

Homepage with my DIY hifi stuff

Maarten Stevens

I have replaced with another 1uF 63V WIMA... then K2 doesn't activate again!

So: it only works with C4 and C5 empty, but I do see a spark then inside K2 relay (and of course there is no softstart then...)

Maarten Stevens

what is the required rating of the caps in C4 and C5?

peranders

63 V, polyester is enough. I must say you have a mysterious error.
/Per-Anders Sjöström, owner of this forum

Homepage with my DIY hifi stuff

Maarten Stevens

I haven now also tried a 250V MKT in that position... still doesnt work. As the designer of the circuit... what could be the culprit?

peranders

When the cap is inserted how many volts across it do you get? When you test this do you have a 24 volts power supply or do you use the mains voltage?
/Per-Anders Sjöström, owner of this forum

Homepage with my DIY hifi stuff