wurlyman
Active Member
I'm a noobie, learning as I go. I started this project last October and just did my first 'smoke' test a couple of weeks ago. Wasn't disappointing, got the smoke. Found out that you CAN test the receiver without connecting the two amps so the only parts I was testing that were reworked were the Power Supply P800 and the Tone and Pre-Amp PE01. The problem was in the P800 power supply. Here's a tip for other beginners. We ran the dim bulb tester plugged into a variac and a DMM connected to the main caps so we could see the voltage come up. Everything looked fine with a 60 watt bulb, then switched to a 150 and at full voltage the 470 uf cap, C803 smoked and started to bulge. Here's why. I had replaced the two rectifiers at H808 and H809 with MUR1620 To220. What I hadn't learned yet was those are available in both Dual Common Anode or Dual Common Cathode and the only difference is one letter in the part number, nobody mentioned that. I didn't even know what those terms meant until last week. Of course, I ordered and installed the wrong one which made the polarity of that cap reversed. In the photo of the schematic below you see the two diodes in the rectifier connected together with their Cathode ends. If the diodes had been pointing in the opposite direction they would have been Common Anode.
This post will continue and I'll always try to keep the beginners in mind when explaining things. I'm especially grateful to Steven Tate, Catrafter, rBuckner, MBuras, John of KT, and of course Leestereo.
This post will continue and I'll always try to keep the beginners in mind when explaining things. I'm especially grateful to Steven Tate, Catrafter, rBuckner, MBuras, John of KT, and of course Leestereo.
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