B&W TV Rainy Sunday entertainment, Bush TV22 corpse
Some of you may have seen the very manky TV22 chassis I picked up from RetroTech, very dirty, very rusty! Well, after the epic saga of the GEC, I thought I’d turn my attention to this, just because I wanted to know if the tube was any good.
The base on the tube is knackered, it’s one of the ones with the metal tubular bit between the glass and the Bakelite base with the pins, and it’s the metal bit that’s split and fallen off, leaving the base dangling on its lead out wires. I was mostly worried about the evacuation pip, as you can’t see it, so I had no idea if it was intact or not. Luckily it’s all in good order, vacuum is intact, heater is also, and all the connections to the electrodes!
To begin with I wanted to try the good old ‘cathode imaging’ with a Megger on 1KV, the results were promising!
A bit of an interesting pattern, which can be varied and moved about the screen with the ion trap, and the focus assembly. It’s nice and bright too, even on 500V, so I’m hopeful this tube is going to be awesome!
The chassis looks untouched, every waxy in place, I guess it was just retired working many years ago, sadly it was stored in a very damp place, probably a leaky shed, so I didn’t expect much from it. The Lopty is present, and covered in cracked up pitch, and I have another set that the lopty packed up on ages ago, which I would like to get going again, so I thought it’d be an idea to see if I could get any life from this set. Rather than plug it into 240V AC, even through a lamp or variac, I decided to try a different approach, give it some DC from the bench power supplies! I set the dropper to its lowest DC settings, and connected them up, I can just about manage 135V with them all.
As the heaters began to light and the HT started to climb there were clouds of smoke coming from the RF deck, caused by a shored cap on one of the IF transformers, so it got the snip, it had cooked up a resistor downstream, next power up, more smoke! Another resistor toasted in the RF deck… At this point I said stuff it, and ditched the RF deck! A link on the socket restored heater continuity. Now I was able to get more heater volts, and things were starting to come alive, the line whistle could be heard, and crackles from the speaker, also a nice buzz when touching the input to the audio amp, which surprised me, the speaker is in an awful state! There was no EHT present on the anode cap, but sparks could be drawn from the input to the rectifier, turned out the EY51 had lost its legs, totally rusted off! I guess the heater end had filled with water during storage, and just sat there like that for some time. I haven’t got another, well, not one that’s easily accessible, so time for terrible bodge no.1, fit a DY86! That done, I could now just about manage 1KV, and nothing on screen. First cap to get the chop was the grid coupling cap to the line output valve, replacing this livened things up a bit and got me all of 2.5KV EHT, still nothing on screen. The A1 volts were all of 1.2V, so the cap after the metrosil got snipped and a new one tacked in on croc clips. Now things were happening on screen! A fuzzy line could be seen, but only with the brightness on full, the control seemed more like a switch, only working near the top end, a dab of conductive paint restored proper operation, and now the control needs to be on zero to stop the EHT dropping.
With the line stage mostly working I turned attention to the frame stage, wiggling the controls would make the line jiggle up and down, so there was life there! I just went for a blanket snipping of the caps on the tag strip down the side, tacked in some new ones and that got the frame stage running, I now have a nice raster on screen, albeit out of focus and small, almost certainly because of the low HT volts.
So it looks like a viable set! I now have to decide what to do with it, I was going to rob it for spares, but I have another option, I have a cabinet with a Thorn solid state portable stuffed in it, which was the very first Bush TV22 I bought about a million years ago (2002..) and it’s been lying around getting filthy looks, hidden in cupboards, just because I was ashamed of it (bloody thing cost me a fortune, and wasn’t a proper set!!) so I could bung this chassis in that and make it a proper set! Might make it worth something closer to what I paid for it too.. I also have another chassis tucked away, missing it’s Lopty and a few other bits, so I could even use that as a base to refit all the good bits onto. I also have another RF deck, complete with band 3 tuner, which could replace ‘Smoky mcsmokeface’.. the possibilities are endless, almost!
Excellent approach getting life into the old gal, Lloyd. 👍 It certainly was worth the punt, just goes to show, even when something looks hideous, there are always possibilities.
Citric acid can be used for cleaning the chassis, but it leaves it very clean which sounds odd but after you see all the pitting very clearly. Tried this method on a scrap chassis using a fibre pen to assist in very crusty areas.
I’ll have to give that a try, I’ve got some somewhere!
since things were going so well, I thought it’d be an idea to dig a working RF chassis out of another set and see if I could get a signal through it. The bench power supplies weren’t enough for it any more, so I had to bring the variac and isolating transformer into play, and also set the dropper taps for AC operation (230V setting, as that’s what it was last used on). Wound it up slowly, and at 130V smoke came from one of the 2 green resistors on the tag board, not sure which one, but I guessed that the big fat waxy on top of the chassis was to blame, so snipped it, no more smoke! Line stage running, no picture, EHT was up, 5KV! Undoing the video lead made the screen light up, turned out the Aurora had gone into standby.. with that sorted out, and a quick tune of the RF, the screen lit up, and there was a rough looking test card, fair bit of cogging, and struggling to sync. The line sync then went off completely, and the control was right up one end. I changed the sync coupling cap, and another nearby that looked iffy, no change. Then I ran out of time, so that’s as far as I’ve got! It’s looking pretty good now though!
I'm impressed, I recall seeing and looking over that chassis at Retrotech and thinking that it would be a brave soul who took that on! Glad someone did, and that the tube looks like a good 'un with good prospects for the rest of the set too.
I walked past the poor thing on several occasions, and dismissed it as a dud, just by looking at the tube base, I actually only went back to the stall the final time to see if the 40” Panasonic LCD set was still there, it wasn’t, so then I asked about this.
Well, some progress! One more cap change C14 on the manufacturers data, and now we have sync! We’re now on full mains too, 6KV EHT (checked with brightness down, but still slightly visible pic) focus looks ok, bit blurry at the edges, it’s very difficult to set the focus and the ion trap, I think this is an early chassis that should have had an MW22-18, as the focus assembly gets in the way of the trap.
I’m using the Hedghog today, so I can play something with sound through the set, at first I could get sound, but it was a bit hummy, and quiet, sounded like duff smoothers, but I’ve since found it to be a dodgy valve base on the RF deck for one of the sound IF valves, giving it a damn good wiggle bought back sound, and very loud too! The speaker rattles a bit, and the voice coil is rubbing, but otherwise it’s ok. I’m watching a bit of ‘Insomnium’ playing a live set from during lockdown on it!
Looks like this little telly is going to live, so I’ll have to find spares for the other one elsewhere… I think a lopt rewind will be in order for the one that died, and a new CRT for the PYE LV30 will need to be sourced.
Buying that was certainly well worth a gamble, Lloyd. Having survived this length of time, and now you’ve brought some life back to it, it has to deserve its own restoration. When I was browsing through the forum finding my way around, I thought you had plugged it in, but having read your post properly I can see that your approach is far more scientific than that!
You have an impressive collection of test equipment. What do you use the microscope for?
it’s the first time I’ve used bench power supplies on a valve TV, I just wanted to see if it’d work! It also gets around the possibility of open circuit smoothers causing loads of hum, the smoothers seem ok so far in this set, they run cool, and there hasn’t been any noticeable hum. You can also get more control over current limiting, saves on fuses! I could have probably just used the variac, or lamp limiter. It can be tempting to just plug it in, I have done so in the past! The problem with the TV22 chassis, as I found out with my first one, is the heater decoupling capacitors like to go short at the drop of a hat, suddenly half the heaters go out, and the remainder light up like light bulbs! On sets that use Hunts mouldseals, or those nasty little caps that look like resistors, they tend to blow themselves out of circuit, while the waxy ones in the bush just sit there quietly oozing wax, whilst burning out some of the valve heaters! I found a few were shorted in the RF deck already.
The test equipment pile keeps growing! Those in the photo are my main ones that see most use, the Thurlby power supply normally lives in a cupboard, most of it in the photo was free too, the top power supply came from a place I used to work when it shut down, it was still in its box! The Hameg scope was given to me years ago by a guy who had hoarded loads of stuff, and was trying to clear up, and the Weir power supply was given to me in a large pile of old stuff. Alongside the multimeter I’d say the power supplies are the most useful bits of test gear in the workshop, I must fire them up for something every time I go in there. The microscope is really useful too, particularly for surface mount components, I built my 2 Hedghog standards converters under that. There is more test gear dotted about, mostly hidden in the drawers and cupboards under the bench!
Done a little more, I might have saved the EY51, there was just enough wire left to blob some solder onto, along with some new wire, the heater lights up now, so I’m hopefull! I also fixed them in place with some 5 minute epoxy, as the original lead outs are quite fragile, just need to reinstall it and see if it’s got any emission left. 1st picture was taken down the microscope!
The tube has been removed for cleaning, I have also removed the base to try and repair it, the metal part has 3 splits in it, which I’ve soldered, I did try putting some hefty heat shrink on it, but then discovered the scan coils won’t fit over it! Think I might have to put out a wanted ad for a new base…
Does anyone have any recommendations for what glue to reattach a CRT base? I know super glue is out, what about 5 minute epoxy? Another option could be RTV silicone, unless it has a habit of coming off easily.
Does anyone have any recommendations for what glue to reattach a CRT base? I know super glue is out, what about 5 minute epoxy?
Recommended to me by a TV engineer, I've always used standard Araldite on loose CRT bases and valve top caps, never had a problem.
Yup, that's what I'd use too.
I'll get some ordered 🙂
Got some! Harry’s home hardware in Woodhall spa have it 🙂 better than waiting a week for it to arrive from eBay!
I have managed to stick the base back together, I borrowed a capacitor clamp from the scrap Ekco A22 chassis, it was just the right size for a CRT base! I used mitre bond (superglue) to stick the Bakelite bit to the metal sleeve, and stuck the metal sleeve back together with bits of large solder braid and lots of solder. It took several attempts, as it wouldn’t fit through the scan coils, or would spring apart again… Maybe I’ll wrap something round it once it’s fitted into the set, I was thinking of using heat shrink again, but the thought of using a hot air gun on a CRT base scares me.
All the valves with Bakelite bases need gluing as well, they are all loose!
When I was 15 or 16 I got hold of a TV22. I was so excited and wanted to see it working so I plugged it in. I was rewarded by a flash and a loud bang! The set would only have been about 30 years old then so I think it could have shown a bit more willing 😀 . There was still some traditional TV repair shops around at that time but I couldn’t find anyone who would take a look at it for me, they said they were finished with valves and weren’t interested.
I know you’re sorted now, but in the past they used to fix valve bases and CRT bases on with shellac. I’ve tried using french polish but that was far too runny. I think they must have used something almost the consistency of nail varnish, presumably they mixed it up themselves.
Haha! I’ve done that with stuff before! Sometimes it comes to life and seems to work, then a few minutes go by and BANG! Normally the mains filter cap going off! Shame no one wanted to have a look at it for you 🙁 my first TV22 was subjected to the ‘plug it in and hide behind a chair’ approach, amazingly it did come to life, no raster, but the whistle was there. I have also heard that shellac was used, along with sawdust? I have tried to melt the old material in the past by leaving it in some IPA, but nothing happened.
tonight I have re-attached the base, using some Araldite, and lengthening the lead out wires with some copper wire from old scrap telephone wire. So far so good! I’ll let it set, then tomorrow I’ll check the wires to make sure none are shorted together. There was some glue left over, so I also stuck the top cap back on the PL38.
Incredible work Lloyd! I saw the chassis at retrotech and passed it by thinking it was far too gone even to yield any useful spares! Then later when I spoke to you when you were carrying it out I thought "brave man" ! I am stunned that you have got a picture on it so quickly...
I am following this thread with great interest.
Cheers Rich 🙂
surprisingly it’s not that bad under all the dirt! Looks mostly like condensation damage, the laminations look only lightly rusted on the top of the lopty, I can see bright clean metal in there!
I finished the CRT base last night, soldered the lead out wires, and trimmed them. Gave the tube another quick Megger test, just to make sure all the electrodes were connected to the pins, and it all looks good. One minor snag, looks like this tube has an intermittent partially shorted heater, it was drawing 400ma on 6.3V, and giving the neck a gentle rattle (fingers only this time, no rubber handled screwdriver this time!) made it go away.
I have started stripping the chassis for cleaning now, and so far it’s coming up well.
I had another TV22 with a more severely shorted heater once, lit up like a lightbulb on 6.3V, didn’t last long before it popped, shame because the picture on it was really good! Another set I have with a partially shorted heater is the Stella ST2049a, a 19” 110 degree tube, I have to run that one from a transformer to get a decent picture, otherwise it’s very dim and naff looking.
I’ve been slowly dismantling this TV over the last few days, cleaning and derusting as I go, most bits are coming up well, using vinegar, I was going to try citric acid, but forgot to look for some yesterday!
Anyway, here’s some before and after shots of the focus assembly:
I turned the CRT clamp round too so the ion trap can sit in the correct place (a tip I was pointed to by Helder Crespo over on UKVRR!)
the scan coils cleaned up nicely too, used a paintbrush with some white spirit followed by foam cleaner, and yes, that’s the original rubber wiring! It’s still flexible and the colours came out really well!
also the photos of the tube after repair.
I gave it a good clean and stuck the labels back on. Last photo shows the blob produced by the Megger test, needs a bit of fiddling with the ion trap to get it on the screen!