Pin Out for Commodore 64 Power Supply - Pins 6,7 with no Volts??

[AAGDOS]

My Commodore 64 Power Supply shows pins 2 and 5 at +5 Volts ( 2= GND, 5 = +5V). Pins 6 and 7 are supposed to be at +9 Volts, but when the meter leads are "touched" to pins 2 and 6, and then 2 and 7, the meter shows +0 Volts. The power supply seems to work fine when connected to the computer. What gives??

 

[Chuck(G)]

I thought I replied to this one a day or two ago. The 9V is 9V AC and is not common with pin 2 or any other pin. Pins 6 and 7 are the 9VAC output right from the PSU transformer. Verify this by setting your DMM to AC volts and measure between pins 6 and 7. There is a fuse in this line, BTW, so be careful not to pop it.

 

[KC9UDX]

Also bear in mind that if it's one of the potted supplies (heavy, very solid), it may unexpectedly fry your C64 tomorrow (or at any time).

 

[AAGDOS]

Thanks to Chuck(G) and Space Commander. I did post this two day ago, but it suddenly disappeared on me, so I reposted it. Thank you again for the info. I will confirm this with the meter.

ps...I am mostly a s/w person and have recovered my C64 and V20 but get stymied by some of these issues I don't have the background for!

 

[KC9UDX]

Check this out:c https://easyeda.com/example/Commodo...tage_protection_circuit_simulations-0ht3pLJ42

 

[Hongminh95]

o I should have measured between pins 6 and 7 to get the 9VAC ... And I do have 5VDC, I must have looked away from the diagram and touched the wrong pin