#SPECCY PSU PC#
(That doesn't mean that it may not need service, fx degraded capacitors could lead to excessive ripple and noise/stability issues, but in general that it is not a condition that will damage the connected device.Hello there people, I recently build a new gaming PC and I now experience DPC Latency issues. TL DR - If there is no active regulation in the PSU, the voltage coming from it is likely fine. (Of course, the higher the voltage it has to dissipate the hotter it will get and the more strain is put on it and the shorter its lifespan may ultimately be.) But if you loaded it with say around 1A, 12V sounds a little on the high side - but the Spectrum's regulator should be able to deal with it. 12-15V for a 9V supply sounds quite normal. It is normal that a voltage measurement without the anticipated load is higher than the nominal voltage. If it contains active regulation, that's a failure point that could fail with over voltage - but as I recall, the regulation is ultimately done with a 7805 inside the Spectrum itself (that regulator can still fail with age, but that's another story as long as the focus is the PSU itself). In that case an over voltage failure mode of the PSU is unlikely. I have not serviced this particular version of the Sinclair PSUs, but if they are like the ones I have they only contain the transformer, rectifier diodes and a smoothing capacitor. Posting an image of the insides could assist people commenting on the issue as well. Try to power it up outside its case (being careful not to touch anything on the primary side or to put it on something conductive) - it may help to locate the origin of the noise. The sound probably wont be as regular and you might be able to smell ozone in that case. Maybe a mounting can be tightened, maybe there is nothing to do about it.īuzzing can also be caused by arcing due to fx a loose connection on the primary side, which is worse (from a safety standpoint). You can maybe feel the vibrations if you put your hand on it.
First of all, if you have any reason at all to suspect the PSU, it's not advisable to connect it to the machine until further tests.īuzzing could be just due to 50hz vibrations corresponding to the line frequency in the mounting or inside the transformer itself and is not necessarily critical, albeit annoying. Welcome to the Retrocomputing Stack Exchange. If you do bother, however, you can replace the voltage regulator by a switching one, like a Traco No reason to bother, it will simply transform the rest into heat.
The linear regulator in the ZX Spectrum can easily "eat" the 12.5Volts. Make sure you get a product that is certified as an isolating lacquer spray for electric components - don't use any old paint you might have! This is not quaranteed to help, but might (glues the single components of the transformer together and stops the vibrations). If that doesn't help either, you can try a generous spraying of the sheet packet and windings of the transformer with special isolating lacquer It's normally held together with long screws you might need to tighten. If this doesn't help, check the transformer. In this case, check for loose parts (espcially the PCB on top of the transformer) and try and fasten them. The other (more likely one) is just a mechanical annoyance: The metal sheets or the copper windings (or some other parts) in the transformer have losened over time and start vibrating with the AC frequency. This case is dangerous and a fire and electrical hazard! It's unlikely you could have measured a stable output voltage in this case, but it's still worth checking carefully. One (luckily the unlikely one) is electrical current jumping an air gap in the PSU causing intermittent shorts through an arc.
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