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#1
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Hey Pooh, whats up with the Club 2000 series PSU ?
Graham ,
I get a stream of them in with PSUs that shut down, blow fuses, etc (current a pair of '142s'). They all seem to suffer from extreme temperture from the 2 x 3T regulators on that little U-shaped heatsink rod. No osciallation, and load seems normal per channel-strip (those little shorted yellow caps +17 to -17 is a different story). Is it 'normal' that the 3Ts run the heatsink almost too hot to touch, or is there something more obscure causing this, AC secondary comes out 22v as it should, so it's not that. Surely they don't all run that hot ? geoff |
#2
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Geoff Wood wrote:
Graham , I get a stream of them in with PSUs that shut down, blow fuses, etc (current a pair of '142s'). They all seem to suffer from extreme temperture from the 2 x 3T regulators on that little U-shaped heatsink rod. No osciallation, and load seems normal per channel-strip (those little shorted yellow caps +17 to -17 is a different story). Is it 'normal' that the 3Ts run the heatsink almost too hot to touch, or is there something more obscure causing this, AC secondary comes out 22v as it should, so it's not that. Surely they don't all run that hot ? Curious that you mention this so long after they went on the market. The heatsink does run fairly hot but never heard of a 'stream' of them causing trouble. Possibly might be a bad batch of voltage regulators shutting down prematurely. That wouldn't explain blown fuses normally though. Technically, the regulators will operate OK at heatsink temps of around 100C would you believe ? Ahhh - but there are insulating washers are there not ? Maybe our Indian friends skimped on the thermapath ? That would explain it ! As would poor metalwork ( burrs - flatness ), preventing a decent thermal interface. The company that made that product for us gave us endless headaches. They still make some of those models ( original Studiomaster designs ) for other companies now too. The psu caps you refer to are the 0.1uF ceramic multi layer types I guess. Turns out that some don't like their rated voltage in that application. I would suggest replacing with 100V parts when required. Cheers, Graham |
#3
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Pooh Bear wrote:
Geoff Wood wrote: Graham , I get a stream of them in with PSUs that shut down, blow fuses, etc (current a pair of '142s'). They all seem to suffer from extreme temperture from the 2 x 3T regulators on that little U-shaped Curious that you mention this so long after they went on the market. The heatsink does run fairly hot but never heard of a 'stream' of them causing trouble. 3 in 2 weeks. And intermittantly but regularly over the last few years. May be a component aging thing, or maybe they used crap thermal compound that loses something. Washers appear to be mica. geoff |
#4
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"Geoff Wood" -nospam wrote in message
Graham , I get a stream of them in with PSUs that shut down, blow fuses, etc (current a pair of '142s'). They all seem to suffer from extreme temperture from the 2 x 3T regulators on that little U-shaped heatsink rod. No osciallation, and load seems normal per channel-strip (those little shorted yellow caps +17 to -17 is a different story). Is it 'normal' that the 3Ts run the heatsink almost too hot to touch, Too hot to touch for very long is only about 125 degrees F, which is nothing at all for a 78xx or 79xx chip to handle. You can make crude but sometimes helpful measurements of the temps of electronic parts with those little dial thermometers that air conditioning technicans use. They're under $10 in car parts stores in the US, don't know about the UK. or is there something more obscure causing this, AC secondary comes out 22v as it should, so it's not that. Surely they don't all run that hot ? For reference purposes, Rane runs the power supplies in most of their signal processing gear from a 18 V transformer via a voltage doubler running into the regulator. Last time I measured the DC going into one it was over 30 volts with 120 vac line voltage going in. The chips run hot, but IME they typically last a few decades, at the least. http://www.rane.com/pdf/old/pe15sch.pdf page 2. Later production uses 317/337 chips instead of 7815/1915, but for this question, same diff. |
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