this question relates to the PSU fitted in one module of my Memotech Videowall system. The original question was raised on Facebook when I could not identify the model number of the PSU and I was lookinig for a suitable replacement. I have now identified the model number (Skynet SNP-3031), there is a replacement available from Skynet, the SNP-9031. Whilst I will try to source one as replacement, I also want to see if the faulty PSU is repairable, so have raised this thread to capture the most relevant information from the Facebook page and ask for additional support from the Group here.
Input specifications: 120V-1A, 240V-0.5A, 50/60Hz.
Output specifications; V1: +5V/2A, V2: +12V/1.5A, V3: -12V/.3A
Mark (Kinsey) had identified the control IC (a UC3842) from the photo on the Facebook page, and made some suggestions, including :-
" Have you been brave enough to do any tests on the PSU with a meter? It could be as simple as some defective electrolytic capacitors (mains filter, or output filter), a faulty start-up capacitor or resistor, or a faulty opto-isolater. I assume you have checked the fuse? If the fuse is okay, it is likely that the input bridge rectifier diodes are okay (they normally take out the fuse when they die)."
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Current Status - bad choice of words - the output is of course, currently 0
- the status of the fault finding is as below
When I initially inspected the PSU, all of the components looked OK physically, apart from the mains input filter capacitor - I could not decide whether it had leaked some electrolyte, or whether it was fixed to the PCB with an adhesive of some sort. Subsequently, I removed the capacitor and found that it had actualy leaked from the vent plug at the bottom, although a close look at the top of the capacitor suggests that it is slightly "bowed" - possibly due to the lid bulging, under the plastic cover.
I have replaced the capacitor and still have the same problem, I guess that the failing capacitor has taken out some other component(s) on the board. I'd appreciate some additional pointers as to where the problem might be and whether I can do any additional checks before replacing components on a "trial & error" basis.
I am not getting any voltages on the secondary side of the transformer, so it's probably a fault on the input side of the board, rather than the output/regulation side.
I can't find a schematic on the web, but Mark indetified the control IC as a UC3842, and I have identified the input rectifier as a SN1B. The rectifier seems to be working, with ~340VDC on the output.
regards
Dave
plus the gardening, DIY/repairs and other outside related activates)...
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