27-07-2020, 04:10 PM
I did check the winding resistances first. But 350 on the HT might have been k, holding tips hard against tag to get a reading instead of OL?
No HT due to tight transformer wire and snapped right at the tag. Fixed that.
The 33 Ohms is too high due to the different characteristic of the 2 x 1N5408 compared to the selenium. The original 21 Ohms which I doubt is original is maybe a shade over 22 Ohms and will be more as it self heats. I put 100 Ohms across it, not having an 18 Ohm of sufficient wattage. The voltage was then closer to target. With no load at all, the 1N5408 pair limit the voltage to just about 1.48.
The HT is a little high with 12K load (maybe 111V?) and OK with 7.5K load. I left the log book in the WS. The LT is still just below 1.4V on the 200-210 range with 12 Ohms load. It's about 1.32V on the 240-250V setting and close to 1.36 on 220-230 (we have about 230V). I added a 33K "bleed" on the HT out, not in original, though it's a fairly standard thing. That puts the HT at about 126V with no load.
Next is screwing it back into the case. The pea lamp lights :D
I fitted a mains lead with an inline on/off switch. I'm tempted to buy about 20 such things for mains stuff that has no actual off switch and does nothing at all useful except light a red or blue LED when off. Most of it doesn't even "boot" faster compared with plugging it in. Though oddly a satellite set box bought last month has a real on/off that actually disconnects the mains on the rear panel. The Sky boxes long ago only powered of the modulator and muted the AV out, even ones with no HDD. Later they introduced speculative downloads to a reserved part of the HDD which you couldn't disable. No idea what they do now.
No HT due to tight transformer wire and snapped right at the tag. Fixed that.
The 33 Ohms is too high due to the different characteristic of the 2 x 1N5408 compared to the selenium. The original 21 Ohms which I doubt is original is maybe a shade over 22 Ohms and will be more as it self heats. I put 100 Ohms across it, not having an 18 Ohm of sufficient wattage. The voltage was then closer to target. With no load at all, the 1N5408 pair limit the voltage to just about 1.48.
The HT is a little high with 12K load (maybe 111V?) and OK with 7.5K load. I left the log book in the WS. The LT is still just below 1.4V on the 200-210 range with 12 Ohms load. It's about 1.32V on the 240-250V setting and close to 1.36 on 220-230 (we have about 230V). I added a 33K "bleed" on the HT out, not in original, though it's a fairly standard thing. That puts the HT at about 126V with no load.
Next is screwing it back into the case. The pea lamp lights :D
I fitted a mains lead with an inline on/off switch. I'm tempted to buy about 20 such things for mains stuff that has no actual off switch and does nothing at all useful except light a red or blue LED when off. Most of it doesn't even "boot" faster compared with plugging it in. Though oddly a satellite set box bought last month has a real on/off that actually disconnects the mains on the rear panel. The Sky boxes long ago only powered of the modulator and muted the AV out, even ones with no HDD. Later they introduced speculative downloads to a reserved part of the HDD which you couldn't disable. No idea what they do now.
