42-PT92 - Printable Version
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42-PT92 - dal61 - 02-25-2017
Howdy. Well, I'm getting around to re-capping this thing...and need to order some caps. This is the first thing I have worked on that has been worked on, and maybe goofed up, by somebody else. There are a few replaced filter capacitors that seem to be what the schematic calls for. It specified 2 - 20 mfd electrolytic caps, but the schematic did not mention voltage. At some point, they have apparently been replaced with a 50mfd and an 80mfd (multi-cap, can't see a voltage on it, either). First of all, would there be any reason to do this (replace with 50 & 80mfd)?...and second, I was going to order new 20mfd, 450volt electros. Any reason to think these won't be ok (voltage wise)? Thanks in advance for the advice.
RE: 42-PT92 - morzh - 02-25-2017
Well, in transitones the value of caps if higher wouldn't matter much but you have to find out the datasheet for 45z5 or whatever it uses for rectifier and look up the max capacitance of the load.
RE: 42-PT92 - Ron Ramirez - 02-26-2017
As the 42-PT92 is a transformerless AC/DC set, there is no need for 450 volt electrolytics. Two 20 uF electrolytics. rated at around 200 VDC are sufficient.
While you certainly could use 450 VDC electrolytics, in this case it would be overkill as these will not be seeing more than around 170-176 volts, maximum. Probably not that much, actually; more like 130 to 150 VDC.
Now, as to your first question...why...maybe that's what the previous owner had, and just used them for the sake of convenience? We do not have the ability to read the minds of others...and that is probably a good thing.
RE: 42-PT92 - dal61 - 02-26-2017
Thanks very much, fellas. I thought I'd be overkilling with the voltage, but thought I'd rather be safe. I'll adjust my order and get it coming.
Thanks, again, it's good thing to be able to pick your brains.
RE: 42-PT92 - dal61 - 03-12-2017
Hello again- I've got another question for you all....I seem to have a break in my loop antenna. It is still present and attached, but no continuity. I've not had a chance to investigate further...just a quick test today. After having trouble tuning stations after recap. I contacted a long time friend and 84 yr old, retired tv/radio guy to help me do alignment...and he suggested I check the antenna (never crossed my mind....duh). So sitting here this evening, I'm wondering what my options might be. Repair?...replace?...fabricate another?...I'll have time tomorrow to see if I can figure where it is broken...and if its broken only in one spot. Anybody have thoughts on this??
RE: 42-PT92 - morzh - 03-12-2017
See if you could visually locate the broken wire. If you can then try to repair it by pulling the broken segment and splicing it.
Loop antennas are not critical towards the repair.
RE: 42-PT92 - dal61 - 03-12-2017
Honestly, this is what I thought...but wasn't sure. That is some small wire to repair.....
Thanks, morzh.
Dean L.