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Commodore PET help!

Hello,

Thank you both for your advice. I still unsure with checking the voltage readings on these pin out connectors, how exactly do I do it using a multimeter sorry if it sounds stupid but I just need to confirm what I think I should do it what I am meant to do.

I am near Bristol so looks as if your traveling in the wrong direction to visit me unfortunately. It's a shame as I could really use the help!

I'll try and have a look at it soon.

Thanks

Edit: don't worry about replying to my question about measuring pin out voltage - your post before the last answers it all.
 
but I have noticed some difference between both PET's, for example, the 4032 humming noises from the transformers is a lot louder, and humming comes from the back of the CRT, this isn't present in the 8096 which makes me think that the CRT isn't even switching on??

Don't worry about the CRT until we find that the 6545 CRTC is being initialized by the CPU and a proper 20 KHz Horizontal drive is being generated. The video board needs this signal in order to generate the 10 KV high voltage. In fact it might be better to disconnect the J7 connector from the main board to the video board until we know the video vertical and horizontal signals are good.

The hum in the big power supply transformer in the Model 4032 chassis may be caused by slightly loose bolts holding down the transformer allowing the iron laminations to vibrate at 60 Hz. Torque down the four bolts. Also felt washers under the standoffs may be used as vibration dampers. If however, the hum is super intense, you may have a faulty transformer.
-Dave
 
Hello Dave,

The louder humming is coming from the flyback transformer whereas the flyback transformer in the other pet makes no sound at all.

I will disconnect the j7 connector and the power connector to prevent further damage.

Haven't had the time to check the voltage readings yet. I'm going to check the disk drive first, was it +5 and -12 volts, can't remember what you said?

Thanks,
 
On the PET itself the (DC) voltages are +5V, +12V and -5V DC.

On the 8050 disk drive it is +5V and +12V DC (but note that there are two separate voltage regulators for the +12V supply - so you have +12VA and +12VB).

Dave
 
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