[sdiy] TX802 Power Supply failure (replacing 3W with 5W resistor)‏

Gil W. gil_we at yahoo.com
Thu Mar 13 10:14:40 CET 2014


So I replaced D5 with UF4007, Q1 with 2SC3572 (equivalent to original 2SC3559), the 7915 and 7815 with fresh ones, and the PC817 optocoupler. Also put a new 22ohm/5W instead of the dead R1. I powered up and nothing... can't get the final +15/-15/+5 volts.

The two other fast 1SS84 diodes has some marks of greenish acid on the leads. Could this have taken D5 out in the first place ? The do not short, however. These are D2 and D6.. Could Q1 take out the T1 transformer while shorting ? I also think about recapping it. Do you think there's a point insisting to fix this ? couldn't find other bad components so far (well, checked only diodes and transistors).

I think I have a Polysix powersupply board laying around. Will it do the job ? IIRC it should make +15/-15/+5/-5 volts...

Thanks again !

On Tue, 3/11/14, Colin f <colin at colinfraser.com> wrote:

 Subject: Re: [sdiy] TX802 Power Supply failure (replacing 3W with 5W resistor)‏
 To: synth-diy at dropmix.xs4all.nl
 Date: Tuesday, March 11, 2014, 4:14 PM
 > Good luck!  If it was me I think i'd consider
 retro-fitting a 
 > whole new SMPSU if you can find one that will fit.
 There is a metric shedload of room.
 My TX802 supply died.
 I replaced it with a 5V SMPS line lump and a simple linear
 supply for the 15
 volt rails.
 Much simpler than messing with that nasty looking switcher.
 By the time it had died a fair area of the PSU PCB had
 blackened, so even if
 I had identified the component(s) at fault, it might need a
 new PCB.
 Colin f
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