Looking at those reminds me of the superb replicas Brian made for his GEC rebuild as shown here mid way in his thread.
Slowly but surely your mapping the PSU excellent. ? By reverse engineering, you are going to end up providing the long lost circuit, should anyone else be lucky to find one of these sets they will be mighty happy.
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Looking at those reminds me of the superb replicas Brian made for his GEC rebuild as shown here mid way in his thread.
Slowly but surely your mapping the PSU excellent. ? By reverse engineering, you are going to end up providing the long lost circuit, should anyone else be lucky to find one of these sets they will be mighty happy.
Hi Chris,
Unless I have missed something, the PSU circuit is now complete. If you would like to add it to the library then feel free.
Just had a look at Brian's capacitors, they are a work of art!
Jon
BVWS Member
The smaller (C3) capacitor also has 4812 stamped on it, would this be DEC 1948??
If it was a date code, more likely week 12 of 1948.
Yes of course!
Jon
BVWS Member
Hi.
I have never had one of those oil filled caps fail. I do have a goodly few though in the loft if on the off chance you do have a failure. The PSU is basically bullet proof and should re-awaken with no trouble. Just treat it like an old car engine that's been dormant for years, never hit it with full mains or a full throttle, slowly ease it into life.
One little trick with a set with a valve rectifier is to pull the rectifier and run up the rest of the valves with no HT this can confirm you don't have any valve or the the tube being down to air and also if you refit the rectifier there will be some initial load and stop the HT zooming up, with a valve HT rectifier I usually start the variac at 100v.
Cheers,
Trevor.
MM0KJJ. RSGB, GQRP, WACRAL, K&LARC. Member
So I have managed to get a bit of workshop time to continue with the Dynatron. Can't believe how long it is since I last worked on the set!
My variac is out of commision at the moment due to another project I'm working on (more on this when it's finished) so I am unable to wake up / test the PSU at the moment.
I have found a replacement on/off switch and some 2 core cable to replace the origial wiring to the mains switch. I have reinstated the PSU to the chassis in readiness for testing.
Unfortunately I have now discovered that the wiring from the PSU to the main TV chassis is also rotten and will need to be replaced before I can go any further. It is gone very hard and the insulation is very brittle and has started to fall off in places.
Here are a couple of examples of the state of the wiring.
Here are the old and new switches.
The switch is not exactly the same, but a very close match. I might even take the old switch apart and see if it can be repaired, this type of switch is quite easy to take apart and rebuild once all parts have been cleaned and then a couple of small nuts & bolts to replace the original rivets.
Jon
BVWS Member
Hi Peter,
I got that one off eBay. I think that was the only one he though. I will see I can find out who the seller was.
Jon
BVWS Member
Hi Peter,
Can't find the seller as it was too long ago. However a quick search on eBay for 'ball ended toggle switch' gives you the same thing. Hope that helps you.
Jon
BVWS Member
I had trouble with one of those style of switches on a table lamp a couple of years back, and couldn’t find a replacement that looked the same, I ended up making a few modifications to the switch so that operating the toggle would push a pin out of one end of the switch, which in turn pushed a 250v rated microswitch! A lot of messing about, but at least there wasn’t any leakage to the toggle any more! There was a thread on here about it somewhere too.
Regards,
Lloyd
