PL 3300 Series II rebuild/upgrade
- Thread starter scottonnob
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Wow! I just received a pair of boards from Perry. I guess I wasn't paying attention, because I thought I was just buying the empty PCBs. However, I opened the box and found fully populated boards ready to be installed. Great bargain. A hell of a contribution to the PL community. Many, many thanks to Perry for all the time and energy it required to have these boards produced.
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- Fondler errrr... fan of all Nav's avatars
The purpose of the regulators is to keep the +/- outputs at 15 volts over a wide range of input voltage. The spec (P.3 of the manual) says the range is 90-132 vac. 132 is 10% high from a nominal voltage of 120 volts. 90 volts is 25% low from a nominal 120. Typical power supply design is +/- 10% from nominal. I would suggest using a variac to drop the line voltage to 108 VAC and make sure the input voltage is still above the minimum input for the XX15's. If it's borderline use XX12's.
It wouldn't hurt to put a reverse clamp diode (1n4004) from input to output of the regulators to make sure the output cap of the regulators discharges properly at turn off. To do this on the 7815 the anode of the diode connects to the output, the cathode (band) connects to the input. The polarity of the diode reverses for the 7915. If a scope is available look at the output of the regulator with the variac set at 108 VAC and make sure it doesn't oscillate or show other signs of instability.
I just noticed that the schematic Perry posted has reverse clamp diodes from output to ground. Although it won't hurt anything they probably won't do much either.
It wouldn't hurt to put a reverse clamp diode (1n4004) from input to output of the regulators to make sure the output cap of the regulators discharges properly at turn off. To do this on the 7815 the anode of the diode connects to the output, the cathode (band) connects to the input. The polarity of the diode reverses for the 7915. If a scope is available look at the output of the regulator with the variac set at 108 VAC and make sure it doesn't oscillate or show other signs of instability.
I just noticed that the schematic Perry posted has reverse clamp diodes from output to ground. Although it won't hurt anything they probably won't do much either.
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Spent the day mounting the board Perry got to me. I'd already installed the wiring when I was soldering in other parts on the board. I had some threaded 1" nylon stand-offs laying around, but there really isn't enough meat on the PL board in that area to allow for drilling without risking hitting a trace. So I just hot glued the stand-off, then drilled Perry's board and ran a #6 screw in there. Many thanks again to Perry. I still can't believe he only charged me around $10 for the board, and he tells me he has a couple more left, if any of you guys are interested.
Also, it was really nice to plug in the OPA 2134's Dennis was generous enough to sell me. He's a great asset for parts.
Also, it was really nice to plug in the OPA 2134's Dennis was generous enough to sell me. He's a great asset for parts.
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