This is a very recent resurrection/restoration from part of my collection. An AWA/Murphy 20 inch V50 chassis made towards the end of 1960's. This was a later version from around 1970/71.
A hybrid model using a solid state tuner/IF strip/Sound IF up till the PFL200 video output and the rest of set is valve. From a comment left on a YouTube video I did on this apparently has a very similar layout to the UK Bush/Murphy TV161 chassis and upon looking up that chassis it certainly does bear a striking resemblance.
I got this about 15 years ago from a recycling/e-waste drop off centre as the bloke who ran the place knew I collected old TV's. It was full of leaves and flower petals when I first took the back off so must've had pot plants near it.
It did require a bit of work to get the thing up and running properly, a number of those dog-bone resistors had gone way up in value and there were the usual leaky capacitors in the vertical stage. Suprisingly the main filter capacitor/s formed up perfectly so have been left in place. Someone had been fiddling around with the AGC control so when I first got a picture on the CRT it was very washed out but didn't take long to figure out what was going on. I don't think this had been running for decades prior to me firing it up on the variac.
Another issue it did have was after about 5-10 mins of running the boost voltage would start to rise on its own - this turned out to be the PL504, my guess is the valve was a bit gassy and started producing a bit of postive grid current. Didn't help that the 2.2M stablizer/set eht trimpot had gone down to about 1500 ohms and the other associated resistors were a mile out.
So it was just a case of going through and replacing the out of spec components and a dud PFL200/tired DY87 and then setting up picture geometry etc. Maybe went a little overboard in the resistor replacement, but there were quite a number that were 'way' out.
Needless to say it now performs great and gives a nice picture. I've been using it for a few hours over the past couple of days and seems to be very stable..until the back goes on!
Something a little different from across the pond in Kiwi-Land!
Very nice, no doubts about it’s RBM A640 chassis heritage although I would never have guessed RBM without seeing the back cover removed. Judging by the British valves and components I wonder if the main chassis was supplied prebuilt from the UK and the rest of the set sourced down under?
Absolutely fascinating on several levels, thanks for posting it Glen!
A few points of interest:
1. The AWA 50 series chassis in Oz was a VERY different beast. Point to point wired and a real dinosaur that continued in production much longer than it should have.
2. AWA / MSP / AWV - sourced CRT, tuner, speaker, line transformer and yoke. Slider pots are Alps, also used by AWA at the time. CRT label is interesting, it's quite different to the one used here. AWV never labelled any of their CRTs "Deep Image".
3. The PCB attached to the top of the tuner looks like it would contain the handful of components that are normally hand-wired to the feedthru caps on that tuner. Never saw a PCB like that done here but it looks like a good idea. PCB would need to have plated-thru holes which will make it very difficult to remove.
4.The channel knob looks like the same one that AWA used here on some mid-sized TVs.
5. PCB panels are definitely British. Could easily have been supplied pre-built. A large haul of passives replaced for the relatively recent build date. Are all those caps paper?
6. The only hybrid AWA ever made was the iconic 17" P4 portable "tribrid" (valves, transistors and an IC)
In case you or anyone else finds it useful, I've attached the native resolution PM5544 card that I use, played on a media player. The stretch is intentional, it's so the media player's slide output will display correctly on a 4:3 TV.
Thanks for the replies everyone 🙂 Ian, I did wonder if this set carried any parts/cosmetic parts that may have been similar to the Australian counterparts. In regards to the circuit boards being pre-made/built up, its hard to say but looking at the UK RBM640, it does look almost identical. Those caps I don't think are paper but they were faulty causing vertical linearty issues and so forth. The others were changed really for preventative maitenance. Also the width wasn't right and this turned out to be a 0.15uf coming of one side of the horizontal deflection coils and numerous resistors were way out.
Just had a closer look, that's not a PCB on top of the tuner, it's a mounting bracket.
A close look at the AWV CRT label - it reads "Made in New Zealand".
I didn't know AWV had any plants other than their big one at Rydalmere in Sydney.
Intriguing!
That tiny turret tuner was first seen in the AWA P4.
I'm not sure where the CRT's were made here but there were quite a few tube manufacturing plants in NZ. The service manual mentions two tuner options - The TCM 300, the tuner in this V50 (which I'm guessing is the same as your P4 sets) and the National ENT6755 EB
Makes me wonder how often NZ & Australia were consulting each other during this period of TV manufacture..very interesting!
A close look at the AWV CRT label - it reads "Made in New Zealand".
I didn't know AWV had any plants other than their big one at Rydalmere in Sydney.
Intriguing!
That tiny turret tuner was first seen in the AWA P4.
@glenz75 I'll try and find details and its designation but there was a single-standard version of the A640 chassis briefly here in the UK - not the A774, which was inferior.
I'll try and find details and its designation but there was a single-standard version of the A640 chassis briefly here in the UK
John covered the variants in a post back in 2019, I think the one you're trying to recall would be the A793?
The last dual standard version of the A640 was known as the Z146, the single standard version sans system switch and 405 line components was I believe A793. The chassis frame was slightly smaller than the original A640 and the two smoothing cans were incorporated into a single unit.
Models such as the TV191 could come in three guises depending on the suffix. TV191D used the dual standard Z146 with 6 button VHF/UHF tuner of course, The S version with the A793 and four button UHF tuner, lastly the SS with the dreadful A774 chassis.
As to the A816, it was not a favourite of lots of engineers but I rather liked them. Performance and reliability was far better than an A774
And the AWA P4 bears no resemblance.
Although the chassis has a resemblance to the A640 only the frame and audio stages have been carried over, all the rest is a complete redesign. The care taken with the sync separator, line flywheel and oscillator stages make me think that this was designed to work under weak signal/fringe conditions.
Yes that'd be right as back in the day coverage was a bit hit and miss as we didn't have that many transmitters or signal translators and with a number of remote/rural areas of NZ here the set would have needed to cope with a weak signal etc.
Although the chassis has a resemblance to the A640 only the frame and audio stages have been carried over, all the rest is a complete redesign. The care taken with the sync separator, line flywheel and oscillator stages make me think that this was designed to work under weak signal/fringe conditions.
I like that P4 its quite cool. Can see the yoke/tuner look to be indenitcal to whats in my V50.
And the AWA P4 bears no resemblance.
Putting a working TV in that shape was a challenge as you might imagine.
I believe the brief to the Tuner division went something like "take our existing tuner, reduce all the dimensions by half and put transistors in it"!
That'd be great, would be good to try and find out what variant we got here or what the V50 chassis was closely based on 🙂
@glenz75 I'll try and find details and its designation but there was a single-standard version of the A640 chassis briefly here in the UK - not the A774, which was inferior.
Did the heat warp the plastic on high hour sets by any chance? Yes haha, give me a valve tuner any day!
Putting a working TV in that shape was a challenge as you might imagine.
I believe the brief to the Tuner division went something like "take our existing tuner, reduce all the dimensions by half and put transistors in it"!
Never saw a heat warped cabinet on a P4.
There are no huge dropper resistors in Oz TVs!
They were fairly efficient and didn't get that hot. There is a metal heat shield above the line out and damper valves.
