575 restoration


John
 

My 575 mod 122C arrived at the weekend. It did basically work when brought up gently on a variac. I've been through most of the valves and replaced a few which were well down on emmision, including the 6AQ5 /V810.
Similarly, most of the paper caps have been replaced with polyester 600V. I've just been through the cal. procedure and everything seems fine, but there is now a slight dot-pattern on the trace which I don't recall noticing when it had the "old" caps and "old" valves in place. As there doesn't appear to be any Z-mod capability, I'm wondering what might cause this? Or is it normal? I've checked the -1700V with a P6015 probe, and it looks clean. There's small amount of ripple on the +2300V anode, but only c 20V p-p.
Photo album uploaded under "575 dot-pattern trace"
John

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