I'm about to restore a TU56H Dectape drive. So far I have been cleaned it up a bit, replaced the motor capacitors. I have slowly reformed the big capacitors in the power supply and yesterday I tried it for the first time. I got really hot!
Looking at the schematics there are a 100 Ohms resistor in parallel with the big bulk capacitors on both power rails. The one on the 38V rail got really hot! Is this normal?
Schematic: http://www.bitsavers.org/pdf/dec/dec...nual_Jan73.pdf on page 71 (pdf-number).
I measured the voltage on the rail to 43 Volts, this gives a power dissipation of 18W! I'm not surprised that it gets hot! I guess that the voltage will drop a bit when the supply is loaded, but with the nominal 38 Volts it will generate almost 15W of heat...
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