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

[Neil Johnson]

Being serious for a moment, SMPS are one the areas where if you don't
know what you're doing then you really are putting your life in
danger.
May I ask, when you're testing are you running it from an isolation
transformer, at a lower AC voltage?  From a socket protected by an
RCCB?  With one hand in your pocket?

Follow Colin's advice.

Neil

On 13 March 2014 09:14, Gil W. <gil_we at yahoo.com> wrote:
> Hi.
>
> 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.
>
>  Cheers,
>  Colin f
>
>
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