The LV transformer is good, the filaments are sourced from that transformer except for the 8393 Nuvister vert input amps.
The HV transformer supplies the +250V, +85V, +100V, +12.6V, -100V & -3000V.? It runs from a 30KHz oscillator.
ChuckA
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On 5/2/2024 5:04 PM, John Dickens via groups.io wrote:
My memory isn’t good on this, but 30 years ago I had to wire in a separate filament transformer for the CRT. I don’t recall the symptoms that led me to this fix. I used a junk box filament transformer which as I recall has the high voltage on it.
On May 2, 2024, at 2:37 PM, ChuckA via groups.io <chuck@...> wrote:
I picked up a Tek 503 scope recently and decided to get it running. Found only one bad filter cap. But it appears the
HV transformer T620 (pn# 120-199) is bad, all the voltages out of it gradually drop after running for a couple of minutes.
The +500v supply voltage is solid, I changed the 6DQ6 oscillator and the 6BL8 control tube but no change.
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