Oh boy! Check out T2's 153 VAC secondary in the power supply schematic. The schematic gives a DC test point voltage after rectification of -205 volts. This is directly across a 4.7uf filter cap that is rated at only 150 volts! How do you know the rectified voltage is going to rise to 1.414 times the AC, and under load it drops to -205 volts DC, and yet you still manage to use a cap with a working voltage of just 150 VDC?
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Golden Eagle 1k
- Thread starter Raider
- Start date
There's one on OfferUp. See https://offerup.com/item/detail/919614251/ See also https://offerup.com/item/detail/847836769/
I recently acquired one of these bad boys, I was going to use a transformer to step down from 240v to 117 ac butt hen I saw the schematic i realised it runs two seperate transformers wired in parallel on the primaries. Was thinking of rewiring botht he primary windings of the transformers in series doubling their impedence and resistance and theoretically then allowing me to run both transformers off 240v mains. I have some concerns about the current draw difference of each transformer as one drives the plate current, the other the filament and grid current and the differential current draw characteristics in potential voltage division over the primary transformers. Has anyone attempted this mod ?
I have the schematic attached for reference:
I have the schematic attached for reference:
Attachments
Won't work that way. If both the 120-Volt primaries draw the same current, they will divide the voltage equally. In this case, the HV transformer will draw more current than the smaller filament/bias transformer. Won't be a proper 50-50 split between them.
We classified this model as suicidal back in the day. Seems to me we worked out a fix for stability issues with the negative control-grid and positive screen-grid bias. Using a neon bulb as a voltage regulator only works until the tiny neon pilot lamp wears out. Feeding 95 Volts to the screen grids is like strapping on a nitrous tank.
That setup may predate the computerized records here. Got spoiled by keeping tech data on disk, and our old paper library has deteriorated. If I can find it I'll post the suicide-intervention we used back in the day.
73
We classified this model as suicidal back in the day. Seems to me we worked out a fix for stability issues with the negative control-grid and positive screen-grid bias. Using a neon bulb as a voltage regulator only works until the tiny neon pilot lamp wears out. Feeding 95 Volts to the screen grids is like strapping on a nitrous tank.
That setup may predate the computerized records here. Got spoiled by keeping tech data on disk, and our old paper library has deteriorated. If I can find it I'll post the suicide-intervention we used back in the day.
73
