So I have checked the voltages across the 7-pin DIN, bridge rectifier and V1 for use with PSU option A. The output from the C64 powersupply is fine at 10v AC, and 5v. After the bridge rect. it’s about 13v DC with out load. Now when I try to read a voltage of C12 there is nothing from Pin 1 of V1 to GND there is about .001v.
Any ideas. I replaced V1 all ready.
Any ideas?
Yes.
1st idea: Mention what pcb it is. It’s your mb6582 I assume?
* Without J71 or J72 plugged in the voltage shouldn’t go anywhere - I’d leave them unplugged for testing 
The vreg needs some minimal load, so you probably should make a little LED+resistor test thingie and hook it up to J71/J72 (basically across ground and the +9V output of V1)
* Is the vreg plugged in the right way around?
* Are C1 and C11 soldered the right way around?
If all of the above is true, and you still don’t get any voltage at the output of V1 go check for shorts again. If that doesn’t solve it you have some major oddness.
Thanks nILS.
Yes the board is rev2 6582.
Caps C11 and C1 are soldered in for the correct polarity.
Voltage regulator is soldered in correctly.
What should the voltages be on the pins for J1A? I am wondering if there is an issue with my C64 powersupplies.
If you measure 13VDC across the - and + pins of the rectifier that hints towards a working psu. The error seems to be after that.
J1A should be what it says on the pcb/in the pdf: 9VAC on Pins 1 and 4 and 5VDC on Pins 2+3
Do some voltage tests directly on the pins of V1… i.e. put black lead on middle pin, red lead on pin 1 and pin 3. (btw pin 1 is the input pin which is on the right).
Between pin 1 and 2, you should measure the same as the output of the bridge rectifier, and same as across C1 and C2 (i.e. from what you said earlier, this is 13V DC).
Between pin 3 and 2, you should measure 9V.
Measure by touching the pins directly, not on other pads. Try to find out if V1 is properly connected to the tracks. Test continuity between V1 pins and pins on the same tracks.
NOTE: V1 pin 2 WILL NOT BE connected to “ground” unless you are using PSU Option A and bridge pins 2 and 3 of J73. To measure if V1 is working BEFORE you connect a bridge at J73, measure directly against pin 2 of V1 as it will only be connected to the “-” pin of the bridge and pins of C1, C2, C11, C12, NOT to ground.
Thanks Wilba and nILS, for reasons I can not explain I replaced C3 and greenwired the traces +C3 to c4 and a few others. I now get 8.92v off V1.
So i either pulled up a pad, had a broken trace, or a defective cap, or defective C64 powersupply.
I am now running off of an iOmega Jaz drive powersupply, with +5v @ 1A and +12v @ .75A.
Hmm too many things replaced to find the cause… Glad that it sorta works now though
Yer, GROT #2