This is a very rare portable TV. It was one of the very few "live chassis" TVs to be made in Australia and was only in production for a brief run in 1958.
It has a mains transformer that operates as an autotransformer for the HT bridge and a conventional transformer for the parallel-connected heaters.
I used to own a green and white one of these when I was in my teens. I fixed it and sold it to a friend at school.
I've never seen another one until this showed up in a Western Sydney antique store for AU$160.
Pete and I fixed it last Sunday.
Here's what it looked like when I picked it up:
And after a clean-up.
It came up quickly on the Dim Bulb. No activity though.
I was dismayed when there was no CRT heater, especially as this CRT was a rebuild from the 60s. I've never seen a good one from this rebuilder!
But no, it wasn't that. No heaters on half the chassis either. A bad termination join on the mains transformer. Someone had been there before. I stripped the join down and made it properly.
Now had sound, no pic, no B+boost. Replaced badly melted waxies and a 220k resistor off the boost that had gone to 5 megs.
Still no boost.
Checked Hor OP G1, -37 volts. G2, zip! OC 3k 5W dropper resistor. Replaced.
And We Have Light!
I put up an Indian Head for the guys in the US!
Focus bad in the middle, bad V Lin, Bad H Lin.
Moved focus tap from CRT G2 to GND. HUGE improvement!
Replaced V Lin pot and wrong value S correction cap. Much Better!
Apart from the vertical circuit where some poor fool has replaced EVERY SINGLE part, (including the 6BM8 / ECL82 and both transformers), and the replacement of most of the waxies some time in the late 60s, this TV still has ALL its original valves and ALL its original electros. All that was wrong with it this time was a bad soldered joint, 2 resistors, 2 caps and a pot. Here is the circuit
Anyone know of a way to make that front plastic clear again? It had become dark brown.
Anyone know of a way to make that front plastic clear again? It had become dark brown.
Have you tried one of those car headlight polishing kits? That might work but it depends on whether or not the discolouration has gone all the way through the plastic.
I always thought those combined autotransformers with isolated heater section the work of Satan: I think there were more than a few Murphy TVs that did it, and even a radio or two.
I always thought those combined autotransformers with isolated heater section the work of Satan: I think there were more than a few Murphy TVs that did it, and even a radio or two.
I recall first encountering that scheme when scrapping (sorry!) a KB radio in my early teens- can't remember the model after all this time but yes, neutral to chassis and the usual transatlantic line-up of 6.3V heater valves. Apart from the 6V6 having been replaced by a 6P25 at some point- that sort of thing must have happened pretty often with so many IO output valves having the same pin allocations. Was it the infamous HMV 1807 TV that featured an autotransformer setup with full-wave rectification, ensuring a few chassis tingles for the unwary? Memory's a bit hazy on that one, so apologies if that's a misconception.
@turretslug Not sure about the HMV, but I always thought this a particular nasty - the KB "Gavotte".
ETA: the HMV wasn't guilty of that, but the Murphy V120C was a bit naughty in its design - it appears to be an isolated chassis until you spot the efficiency diode heater is fed from the 200V and 240V taps on the mains transformer primary.
Ah yes, having looked up the 1807, it wasn't that but there was some early post-war oddity (i.e. copper shortage) that did something unorthodox that brought to mind the "always a surprise" nature of much later solid-state sets with bridge rectifier input.
Found a bit of history of Tel Leigh Tubes...
It would have been a poverty-stricken business selling rebuilt tubes at AU$11 a pop.
@irob2345 Well they seem to have done a decent job with that CRT, I was never very happy with the performance or reliability of regunned CRT’s unless they were from the original maker.
Others on the forum had a better experience.
Frank
Yes Frank, and it came straight up from hibernation like that too. Just needed to right focus tap selected.
No telling how many hours it's done, probably not many given the bad join on the transformer.
I wonder if that bad heater connection was the reason the tube was replaced?
BTW, here is that address today!
"6 Dec 2024 — This character-filled original warehouse with contemporary first floor addition and a large basement cellar offers endless opportunity with its raw and .."
It was sold in 2024 for AU$4,760,000
