B&W TV Rediffusion "Guildford" RT 194/19 Dual Standard
So as I'm typing this I've just got home from a 300 mile round trip to pick this up along with a Pye and of course Chris Crustytv's Granada. When I first saw pictures of this I knew I wanted it! However, I couldn't find ANYTHING online about it. It was only when I forwarded the pics to Chris that we managed to find out that this was Rediffusion's version of the Bush TV 161 with the A640 chassis. As far as I can tell this appears to be from 1964 judging by some of the codes but at the moment I know so little about this particular set.
The channel selector isn't what I was expecting. Bush TV 161s and the related sets usually have the first four channels set to VHF 405 line and the remaining two as UHF 625 line. However, this alternates! First channel is 405 line, second channel is 625 line, third channel is 405 line and fourth channel is 625 line.
It's almost as if someone set it up as BBC 1 (405 line) BBC 2 (625 line) ITV (405 line) and Channel 4 (625 line). I don't know if this is a later modification or what? 🤔
Inside it's clearly a Bush A640 chassis, nice to see the LOPT cover is still intact:
I'm not familiar with LOPTs for this but is this the dreaded tar-coated LOPT?
PY88 has gone to air, but I have a couple of spares in stock.
I can't quite get the camera in and I'm a bit too tired to start hinging down the chassis but the CRT is definitely a Mullard.
So overall this is a very unusual set that I wasn't even aware existed. The "Guildford" name on the front seems to hint that it was manufactured in the Chessington factory (later a distribution and development centre) as I've seen later sets with a similar styled cabinet with "Durham" which would hint that it was manufactured in the Bishop Auckland factory.
The previous owner seemed to be struggling to find information on this as it has "Murphy V1914?" scribbled inside the back cover.
Any information on this is welcome!
@wayned RBM produced the A640 set for a at least two rental companies. I used to have a Granada version which was badged as "Top Rank" I also have a set which is Defiant branded with the CO-OP logo. The A640 is one of my favourite sets probably one of the best dual standard chassis produced.
The LOPT is a weak point. I rescued one before Christmas that had been dumped by a skip and showed signs of being damp. I saw it had one of the old style pitch LOPTs so I expected it to be duff. I left it on a central heating radiator about 3 months and so far it has been OK surprisingly! I think maybe I was just lucky!
The tuner is a mechanical wonder! when you look at the other dual standard sets of the day they usually had two separate tuners and a system switch, as you say on this set the tuner switches standards automatically and without the complication and cost of a solenoid that Pye used on the 368 "Olympic" chassis.
Each button can be programmed to switch Band and system with keys fitted into the front of the tuner these keys are pushed in by the lip on each of the buttons a very clever design.
I see your set is fitted with Mullard capacitors which should save you a bit of work!
Hi Wayne, if it were my set, I'd be inclined to whip the LOPT out and perform this following procedure. Many have followed this with great success, better to be safe than sorry.
@slidertogrid Yeah, the first thing I want to do is get the LOPT dried out as I've no idea how this has been stored. The method of running a current through it to warm it seems to be the most reliable.
I originally thought that Rediffusion TVs were all made/designed in-house but every day's a school day it seems!
We have a date! This is on the bottom. It's a lot later than I was expecting. I was lead to believe that rounder tubes like this has were more of a pre-1965 thing but it shows how much I know...
Also, my friend who very kindly kept this for me until I was able to pick it up informs me that this has been stored in a dry place for at least the past 20 years so that's filling me with confidence! Although I'm still going to make sure that any moisture is out of the LOPT just in case. It would also explain why the 405/625 switching mechanism works very well.
@wayned My sister-in-law's third birthday.
For a Bush to have been dual-standard in 1964 you would have been looking at something like the TV125 family of sets - as you've discovered, the A640 family is considerably later.
I'm sure I've seen these sets with straightforward "Co-op" branding - not even Defiant.
@cathovisor I have very little experience with black and white valve sets so I'm still learning!
It's nice to just be able to look up information on a particular set rather than try to diagnose faults the hard way like I did back in my youth. I remember buying Eugine Trundle's TV and VCR Repair Handbook and finding that it was pretty useless for a complete beginner like I was at the time.
When I was in my teens and first started out repairing this sort of stuff the first point of call was often a letter to the Readers Enquiry Service section of "Television" magazine; I think (hope) I still have the letter I got from them in response to a problem I had on my Pye 368 chassis set.
Later (aged about 18), I inherited a set of the McCourt fault listings books. Those were very helpful indeed, and later still (when I started work) I learned that then, Television Centre had a library which included popular magazines such as "Television" and "Wireless World" - and what it didn't have could be got from the bigger library at Broadcasting House. Of course, I was learning on the job as well at the same time.
Of course, whilst the above helped you fix a set quickly, it didn't necessarily teach you why the fault occurred or why it manifested itself in the way it did.
I'm still firmly of the view that the original two volumes of Spreadbury were probably the best introduction ever to valve TV principles and with those, you learned quickly what could be wrong.
@cathovisor This is my CO-OP Defiant A640 It is easy to miss the Defiant name as it is tiny and right at the bottom of the trim in fact I owned the set for some time before I spotted it. Maybe mine was a retail set and the ones badged just Co-op were the (ex)
Wayne, not sure if you've located the service data for this yet, but if you look in the data library, I believe the file you want is
Do the i/f panel, tuner module and Timebase panel prefixes, match yours?
Ah, I see the A583 sticker just above the frame-TX.
PY88 has gone to air, but I have a couple of spares in stock.
A word of possible caution. I had the same thing on my A640 when I started repairs. It turned out to have a faulty/shorted overwind on the LOPT. It crossed my mind at the time whether this was the cause of the PY88 overheating and causing the glass to crack and let in air. Mine was cracked on the base of the valve.
Just for fun, here is my adventure....
Yeah, I'll definitely do that. Been again watching YouTube videos on ring tests.
I certainly have an oscilloscope!
Ooo, someone's been tidying, looks brilliant Wayne, hope you've planned for more racking, I'm sure we can tempt you with more TVs. 😎