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Author Topic: output transformer fault finding.  (Read 11072 times)

Dmoney

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Re: output transformer fault finding.
« Reply #15 on: March 17, 2010, 10:23:18 PM »
I had a fast blow 1A in.
the power supply has two pairs of UF5408 diodes for the rectifier,
then i think its 4 filter caps at 200uf 300V and four 220K/1W resistors set up as two groups of paralleled components in series to ground. (if that makes sense),
The the Standby switch, HT fuse and choke (in that order), then two more 200uf caps.
OT centre tap is attached to the HT fuse.

the only other fuse is the mains fuse.

jpfamps

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Re: output transformer fault finding.
« Reply #16 on: March 17, 2010, 10:47:37 PM »
OK, that's where I would have had the HT fuse.

Thinking about it 1A is a bit larger than what I would have used, but not excessively, depending on the HT. I probably would have start with a 630 mA.


Dmoney

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Re: output transformer fault finding.
« Reply #17 on: March 17, 2010, 10:53:30 PM »
yeah i was think that.
maybe get a few values and see what fits?

according to my schematic, and i guess this will vary according to PT and a few other varibles,
the OT CT which is right on the HT fuse should be seeing approximately 498V.

I did think about (once i get it running again) starting with lower value fuses until I find a point where the amp settles nicely.