It is currently Mon Dec 11, 2017 1:23 am

The Hertfordshire Rediffusion MK1s

 
Posts: 290
Joined: Fri Jul 29, 2011 8:42 pm
Location: St Albans

The Hertfordshire Rediffusion MK1s

Post by Tazman1966 » Tue Mar 01, 2016 10:17 pm

Hello everyone.

It's been a while since I posted but I had some very sad family news and had to rush off to Cyprus. We're back since Saturday now and today, in order to take my mind off things, I thought I'd take a look at the trio of Rediffusion MK1's I won on eBay that a very good friend kindly picked up for me while we were away.

The first observations are that the cabinets are very tatty indeed, one in particular has a big lump of veneer missing from the top. On opening them up it was clear that the CU2213 had been cannibalised as the timebase panel is missing and there were plugs out on the decoder board too. The other two sets though, a CU2211 and a CU2214 were complete and unmolested. All three had been fitted with re-gunned tubes although a check with the tester/rejuvenator revealed that the one in the "bitsa" was poor particularly the green gun. It is a Thorn New life although it should be called a Thorn no life!

Throwing caution to the wind and after a cursory check over I plugged them in and got some results on both of them! There are a number of faults on both of them and as time permits I will work my way through them. For now though, here are the initial pictures.

Regards,

Tas
Attachments
P3013135.JPG
P3013136.JPG
P3013137.JPG
P3013138.JPG
P3013139.JPG
P3013140.JPG
P3013141.JPG
P3013142.JPG

 
Posts: 2665
Joined: Sun Sep 01, 2013 6:19 pm
Location: Behind the sofa

Re: The Hertfordshire Rediffusion MK1s

Post by Cathovisor » Tue Mar 01, 2016 10:39 pm

To be honest Tas, scraping the cabinet and then applying some Danish Oil would make them look superb from what I can see.

 
Posts: 5844
Joined: Sat Jul 23, 2011 8:19 pm

Re: The Hertfordshire Rediffusion MK1s

Post by crustytv » Tue Mar 01, 2016 10:42 pm

Hi Tas,

Rediffusion-tastic :thumb

Looks like you're going to have a Rediffusion March/April sorting that lot out. There's been a glut of these sets turning up recently which is great. It will be interesting to see how they fair on soak, watch the tripler Gary's CU2213 let go after a few hours. Nice sets to work on, well thought out too and we have the resident Rediffusion guru here Malc. He may even be able to sort you out with a TMB board. Service data as you are aware is in the library :qq1 :thumb

My CU2213 had some bad scratches and water stains, it was easy to sort and as you can see from the main site photos, looks great now. Mikes right a good sanding and danish oil will work wonders.

Chris

 
Posts: 1141
Joined: Mon Jul 25, 2011 11:37 am
Location: Willington, Co Durham.

Re: The Hertfordshire Rediffusion MK1s

Post by malcscott » Wed Mar 02, 2016 12:59 am

Nice lot of sets you have there. Straightforward restorations. I have plenty of spares and help here, Malc.

 
Posts: 290
Joined: Fri Jul 29, 2011 8:42 pm
Location: St Albans

Re: The Hertfordshire Rediffusion MK1s

Post by Tazman1966 » Wed Mar 02, 2016 12:04 pm

Thanks for your comments guys. I get the feeling that these sets may have been stored in less than favourable conditions. The convergence controls in particular a scratchy and rusty too. That's gonna need sorting too.

One set is earmarked for Aiden Lunn who expressed an interest way back when I was bidding.

Ta for now!

 
Posts: 2665
Joined: Sun Sep 01, 2013 6:19 pm
Location: Behind the sofa

Re: The Hertfordshire Rediffusion MK1s

Post by Cathovisor » Wed Mar 02, 2016 1:10 pm

That failure of finish is definitely indicative of damp conditions, Tas.

 
Posts: 290
Joined: Fri Jul 29, 2011 8:42 pm
Location: St Albans

Re: The Hertfordshire Rediffusion MK1s

Post by Tazman1966 » Thu Mar 03, 2016 9:14 pm

Good evening!

A little bit of tinkering yesterday brought some rather better results.

First of all, the CU2214. This had appalling convergence and very bad field linearity amongst its main faults. There was no chance of setting up the convergence as two of the pots were open circuit. They were RV712 and RV710 Red/Green field amplitude and tilt. with one at one end there was a marked improvement to the lin but the convergence was still miles out. Several of the other pots were scratchy too but with none in my spares stash I robbed the panel out of the wrecked CU2213 which looked in surprisingly good nick. I wonder if it had been replaced later in it's life? This now enabled the convergence to be set up and the linearity was now almost correct. When I say almost, there is some foldover at the bottom of the raster. Any ideas on this?

The chroma was a little hesitant to arrive at switch on although could be made to appear by disabling the colour killer. A touch to the ACC preset sorted out reliable colour operation.

The width was a little lacking so I treated the set to a brand new PL509 and PY500 pair. That cured the width problem and speeded up the warm up time too.

So faults to still work through are the small amount of bottom foldover, rather weak contrast, the black level seems to float up and down with picture content and of course there the very bad cabinet to attend to.

As for the CU2211, I haven't really done too much to that other than a very rough set up. Again dodgy convergence pots, the same as above precluded decent convergence and again the lin is not right. The picture in general has a bit more "punch"on this set though. I'll certainly need some of those orange convergence pots - 20ohms centre tap I think. I don't want to do too much to this one though as it may well be passed onto Aidan.

On both sets there is not much range on the brightness controls. Is that normal?

As to the "scrapper" I'm ha;f tempted to borrow a timebase panel from one of the above two just to see what happens. It also needs a new PY500 which has gone down to air - I have a few!

Anyway, here's some pics of the progress so far.

Tas
Attachments
P3033061.JPG
CU2214
P3033062.JPG
CU2214
P3033063.JPG
CU2214
P3033064.JPG
CU2211
P3033065.JPG
CU2211
P3033069.JPG
CU2211
P3033070.JPG
CU2211

 
Posts: 1141
Joined: Mon Jul 25, 2011 11:37 am
Location: Willington, Co Durham.

Re: The Hertfordshire Rediffusion MK1s

Post by malcscott » Thu Mar 03, 2016 9:22 pm

Hi Tas, plenty of nos convergence pots for these here, Malc.

 
Posts: 437
Joined: Fri Aug 26, 2011 10:45 am
Location: Gateshead

Re: The Hertfordshire Rediffusion MK1s

Post by Focus 2 » Thu Mar 03, 2016 9:42 pm

Great results. I'm not at all familiar with this chassis. The only example I remember was a cable version a relative had. It was returned when the service closed in the early '80s.
Brian

 
Posts: 290
Joined: Fri Jul 29, 2011 8:42 pm
Location: St Albans

Re: The Hertfordshire Rediffusion MK1s

Post by Tazman1966 » Thu Mar 03, 2016 9:48 pm

malcscott wrote:Hi Tas, plenty of nos convergence pots for these here, Malc.


That's great Malc. Can I purchase some?

Tas

 
Posts: 290
Joined: Fri Jul 29, 2011 8:42 pm
Location: St Albans

Re: The Hertfordshire Rediffusion MK1s

Post by Tazman1966 » Thu Mar 03, 2016 9:51 pm

Focus 2 wrote:Great results.
There's still a way to go yet mate :)

Focus 2 wrote:I'm not at all familiar with this chassis.
Me neither other than one that my aunty and uncle rented from Rediffusion in Cardiff which replaced a Rediffusion badged Luxor Hybrid set.

Tas

 
Posts: 1141
Joined: Mon Jul 25, 2011 11:37 am
Location: Willington, Co Durham.

Re: The Hertfordshire Rediffusion MK1s

Post by malcscott » Thu Mar 03, 2016 10:28 pm

Hi Tas, let me know what values you need and a pic of the types, Malc.

 
Posts: 290
Joined: Fri Jul 29, 2011 8:42 pm
Location: St Albans

Re: The Hertfordshire Rediffusion MK1s

Post by Tazman1966 » Fri Mar 04, 2016 10:31 pm

Hi Malc.

I need four of the 20ohm ones (with the orange spindle in the photograph) and one of the 200ohm ones (with the blue spindle in the photo). Drop me a message and we'll do business :bba

Here's the photos.
Attachments
P3043061.JPG
P3043062.JPG
P3043063.JPG
P3043064.JPG

 
Posts: 1141
Joined: Mon Jul 25, 2011 11:37 am
Location: Willington, Co Durham.

Re: The Hertfordshire Rediffusion MK1s

Post by malcscott » Sat Mar 05, 2016 3:39 pm

Hi Tas, i have sorted out 4 x 15 ohm and 1 x 200 ohm nos pots. I used the 15 ohm in place of the 20 ohm pots in my Mk1 and they worked fine. PM me your address and i will pop them in the post for you on Monday, Malc.

 
Posts: 1141
Joined: Mon Jul 25, 2011 11:37 am
Location: Willington, Co Durham.

Re: The Hertfordshire Rediffusion MK1s

Post by malcscott » Sun Mar 06, 2016 3:45 pm

Tas, also check the condition of the shift pots on the eht tower sub pcb, Malc.

 
Posts: 290
Joined: Fri Jul 29, 2011 8:42 pm
Location: St Albans

Re: The Hertfordshire Rediffusion MK1s

Post by Tazman1966 » Mon Mar 07, 2016 8:21 pm

Checked Malc. The line shifts pots are fine but the frame shift ones are a bit "iffy"!

Tas

 
Posts: 1141
Joined: Mon Jul 25, 2011 11:37 am
Location: Willington, Co Durham.

Re: The Hertfordshire Rediffusion MK1s

Post by malcscott » Tue Mar 08, 2016 12:46 pm

Hi Tas, convergence pots are on their way. I have included a couple of nos 1k vert shift pots, Malc.

 
Posts: 290
Joined: Fri Jul 29, 2011 8:42 pm
Location: St Albans

Re: The Hertfordshire Rediffusion MK1s

Post by Tazman1966 » Tue Mar 15, 2016 9:58 pm

Hello again and big thanks to Malc for the convergence pots.

I had a little spare time today so set about replacing some of the duff pots in the 2211. The improvement was dramatic as the photos show. There are a few niggles but I'll let Aidan (assuming he still wants the set!) finish things off.

I couldn't resist having a look at whether the CU2213, which if you remember was the one that I reckon had been thrown together using the worst of some other sets, would produce any worthwhile results. In its "as found" condition, the timebase panel was missing and plugs were out on the decoder board. The PY500 was also down to air. I nicked the timebase board out of my CU2214, stuck a second-hand PY in and plugged the decoder back in. If you remember, I stole the convergence board from the 2213 to put into my 2214 as it was in much better nick so I first had to replace a couple of the dodgy pots on the convergence panel that now lived in the 2213. With this done and the mains filter cap snipped, it was time to apply power.

With more than a little surprise, I soon had a raster and after a bit of tuning, signals and sound. The convergence was miles out, the scan coils "on the p1ss", grey scale laughable and no colour but it was a start. I'd already tested the CRT so I knew despite it being a regun, it was very low. With nothing to lose I thought I'd give it a bop with my machine but I reckon someone had been there before me. The green was shot and would not boost, blue not much better although red was pretty good. I had a very quick go at lining it up and it converged ok - from what I could see! Overriding the colour killer produced colour with severe Hanover blinds (bistable trouble?) Anyhow, that's as far as I'm gonna go with that one (I think - although I maybe tempted to get the decoder working!)

I'll move back on to the "keeper" when I have more time and will pick your brains again.

Regards,

Tas
Attachments
Rediffusion 1.JPG
The CU2211 after having the two of the convergence pots replaced, Interestingly, this stopped the bottom cramping too!
Rediffusion 2.JPG
CU2211
Rediffusion 3.JPG
CU2211 switch off blob!
Rediffusion 4.JPG
Duff pots
Rediffusion 5.JPG
The surprise "bitsa" CU2213

 
Posts: 773
Joined: Tue May 29, 2012 1:19 am
Location: Sheffield

Re: The Hertfordshire Rediffusion MK1s

Post by AidanLunn » Wed Mar 16, 2016 8:33 pm

Glad to see it's being awoken by someone more adept at vintage colour TV than myself, and yes I do still want it Tas :)

The plan at my end is to restore all my valve B&W TVs, then go on to my few solid-state b&w sets, then move onto colour. This Rediffusion might provide a good "training ground" for colour before I do both my Thorn 8500s. That way i feel I can make progress into learning the hardware of more complex TV sets, by starting off with the easiest (B&W valve TVs).

 
Posts: 290
Joined: Fri Jul 29, 2011 8:42 pm
Location: St Albans

Re: The Hertfordshire Rediffusion MK1s

Post by Tazman1966 » Wed Mar 16, 2016 9:58 pm

Hi Aidan.

Glad to hear you're still interested. I just hope I have left enough stuff for you to do. We'll have to work out how to get the set to you.

Anyway, onto the basket case CU2213. As I knew would happen, I couldn't resist trying to sort out the decoder. If you remember, with the colour killer overridden, there was some colour albeit wrong and with severe blinds. There wasn't much scientific fault finding other than knowing from the symptoms that it was in the area of the ident/bistable and sure enough a little electrolytic capacitor (C221 12uF) decided to own up by giving off a puff of electrolyte! With this replaced, we now had colour. I then went through the process of setting everything up. This set really had been thrown together using panels from other Mk1's. In spite of the lousy CRT the set now gives quite a pleasing picture. I paid £30 for the three of them so if anyone wants this CU2213, a tenner secures it. The cabinet will require a lot of work and it really could do with a better CRT and of course it'll need a timebase panel as it has the one borrowed from my CU2214. Anyway, here's the pictures of today's work.

Tas :bba
Attachments
Rediffusion 6.JPG
Rediffusion 7.JPG
Rediffusion 8.JPG

 
Posts: 290
Joined: Fri Jul 29, 2011 8:42 pm
Location: St Albans

Re: The Hertfordshire Rediffusion MK1s

Post by Tazman1966 » Fri Apr 08, 2016 7:52 pm

Hello again.

Well Davidh1041 collected the CU2213 so that left two; the CU2211 for Aidan and the CU2214 for me!

If you remember, mine was suffering from a bit of a lack of punch, frame foldover at the bottom of the raster and a certain intermittency of the decoder to work unless you short out the colour killer over-ride briefly. Time for some voltage checks and I discovered that all the voltages derived from the LT supply lines (the 22V and the 24V lines) were down. I checked the voltage at source and the 22V was down at 15V and the 24V about 18V. The supply is derived from a mains transformer and full wave rectifier. Pretty simple eh? Nicking the power pack from the CU2211 cured the faults at a stroke with the LT lines at the correct level. What in this simple power pack could cause this voltage drop? I reckon duff smoothing electrolytics. What do you think?

Tas

 
Posts: 1141
Joined: Mon Jul 25, 2011 11:37 am
Location: Willington, Co Durham.

Re: The Hertfordshire Rediffusion MK1s

Post by malcscott » Sat Apr 09, 2016 1:31 am

Hi Tas, first check the lt supply diodes. If they are the large chunky type they are suspect. Otherwise replace the caps, Malc.

 
Posts: 290
Joined: Fri Jul 29, 2011 8:42 pm
Location: St Albans

Re: The Hertfordshire Rediffusion MK1s

Post by Tazman1966 » Sat Apr 09, 2016 7:36 pm

Thanks Malc. I'll check 'em when I get the chance

Tas

 
Posts: 290
Joined: Fri Jul 29, 2011 8:42 pm
Location: St Albans

Re: The Hertfordshire Rediffusion MK1s

Post by Tazman1966 » Mon Apr 18, 2016 9:38 pm

Hello Malc and all.

Finally had a bit of time to myself. Did some voltage checks and the AC in is correct at just over 22V which is the same as the other set but sure enough the DC side is low. The diodes read ok but I changed them just in case - I used rather beefy 1N5408 types. No change so I reckon it must be the huge (in value) electrolytics. Now to source some suitable replacements! That'll be C600, 601 and 602.

Tas
Last edited by Tazman1966 on Mon Apr 18, 2016 9:40 pm, edited 1 time in total.

 
Posts: 290
Joined: Fri Jul 29, 2011 8:42 pm
Location: St Albans

Re: The Hertfordshire Rediffusion MK1s

Post by Tazman1966 » Thu Apr 28, 2016 7:00 pm

Sure enough, it is the reservoir capacitor C602 (2500uF). I slapped a 1000uF across it which was the highest value I could find and the LT rails rose to their correct levels. This power supply slab is in the CU2211 which is heading north to Aidan so it is he who will have to replace it. With the LT rails low, I found that the decoder didn't operate very reliably, the sound was low, brightness poor and the frame small. With the temporary cap in place it performed very well indeed. There are also two further pots on the convergence panel to replace to get the blue convergence fully up to spec though Aidan - both 20 ohms with the orange adjusting spindles. (R709 and R713)

As to my CU2214, I must have the most unreliable decoder of the trio as the R-Y has vanished leaving rather nasty colour although the grey scale is still fine. My money's on the R-Y amplifier transistor TR216 a pesky BF197 Lockfit type. I'll let you know what happens.

Tas

Next

Return to Black & White Television



Who is online

Users browsing this forum: No registered users and 8 guests