Bush TV22 (yes, another one)

[Stubble]

Hi folks

Found this complete wreck of an early TV22 a few months back but left it as I thought it was past restoration, as you can see from the photos the case is in socking condition I have all the broken parts.

Well while I’m waiting for parts for the TUG34 I thought I would see if I could find any life in the chassis, firstly I spent some time re-wiring, all the rubber power supply and tube loom had perished most had melted into one another and each time you moved them chucks fell off. Fitted a new mains cable directly to the power switch and isolated the old mains connecting pins.

I then connected only the heater chain snipped out C60 hum cancellation cap and powered up, all the valve heaters came up along with the tube heater, looks promising.

[Stubble]

Next I re-connected the main power HT applied power and nothing, the heaters came up, I was about to switch off when the line whistle started, adjusted the brightness control and bingo a very faint horizontal line. After a few minuets the top part of the frame opened out to some sort of raster.
The only sound was a very loud buzzing from the speaker which is ripped to shreds.

[Stubble]

So I decided to continue and restore the chassis, first test was to get the frame out put working so re-capping commenced. One at a time, testing with the Aurora connected
Very weak locked test card achieved but still no sound other than the buzzing.

[Stubble]

Continued with the re-capping of the main chassis, now who in there right mind placed C28 there under the board, and it seem to be the most important cap, the difference changing this pig of a cap was amazing in improving the raster, still no sound.

[Stubble]

After finishing off the main chassis cap changing it brought new problems, the higher HT started melting the old waxies in the receiver, dripping out of the bottom and thick smoke wafting out so this forced me to re-cap the receiver.

Now have good sound even though the speaker is mashed up, I have now address this to a degree with PVA and paper towel pasted over the rips, nothing to loos is it dosent work.

[Stubble]

Niggling faults time.
The raster is jitter at the top and bottom, it also keeps moving in the centre sort of stretching and distorting them comes back also a white diagonal line also across the raster .

I have ordered in some new electrolytic caps ready to change them I would say the C33 is most likely the cause for the jitteriness along with the resistors below.

On testing the resistors the following need changing. Trader 1003/T15
R21 180K reading 107K
R30 820K reading 0.908M
R31 470K reading 0.555M
R24 1.5M reading O/C
R57 2.2M reading 0.464M
R56 680K reading 0.727M

My first question, would any one know the power rating for the above resistors the trader dose not state them, I’m supposing all are quarter watt except R56 which must be around 6 watt?

Any suggestions for improving the tuning adjuster, the knob is missing along with the spring only the channel scale survives.

What would be the best way to go forward with the case? What glue would be suitable and what strengthen would be appropriate, it would have to be on the LOPT side where all the heat is generated, to be frank I have thought of discarding it and making something with ply to house the cassis in.

Any thoughts much appreciated.
Thanks Lee

[mark pirate]

I would clean the case thoroughly and use superglue to hold it in the correct place, then use fibreglass repair paste to strengthen the inside, if you take your time it should go together fine, once the large chunks are in place, do the smaller pieces.

If there are small bits missing you can fill these with car filler.
At worst, you could spray paint the cabinet a colour of your choice, I always fancied a black one

It is certainly a worthwhile project, good luck with it.

Mark

[HamishBoxer]

Re the reses 2W max will be fine or in most cases even 1W if good quality.

[PJL]

Superglue can be pretty tricky stuff to work with on a large join. Play safe and user traditional araldite and use string to keep the bond tight. I reckon that cabinet could be good as new as the breaks are mostly along seams.

The lines are flyback and by the looks of things that is because you are having to set the brightness high. Others can probably give better advice but I would say the tube maybe a bit tired or you may have some low voltages, HT, boost and EHT. Fix the resistors first then leave it on a while.

Regarding the 680K resistor, it is in the frame oscillator so I don't see any need for a high wattage. Keep in mind that the small modern resistors are only good for 250V so I tend to use 2W/500V types.

[Lloyd 1985]

Hi,
That's looking good

I'll add another vote for superglue! On a join as big as this, I'd get the thing to fit into place first, this might involve filing/ dremmeling (is that a word?!) the edges on the inside surfaces only to make it as tighter fit as possible, then dribble the glue in from the back of the join. You'll probably need to find some heat resistant superglue, I saw some on ebay earlier this week, but it wasn't cheap! I'd probably avoid using araldite on this, as TV22's kick out loads of heat, and I'm sure araldite goes soft when heated. Another good thing about using superglue, when its fully hardened after a couple of days, you can sand off the excess and polish up the join and it will be almost invisible, I've used this method numerous times now, overfill the crack with glue, let it set for a couple of days, then sand flat with no coarser than P600 wet and dry (preferably outdoors), then polish with Bakelite polish or T-cut.

It would probably be a good idea to strengthen the cabinet afterwards with fiberglass, as Mark has said, and you can get a kit of it from Halfords, I'm not sure what it's like when it gets hot though. You could always fit a fan to the rear cover! I've done this before on one of my TV22's, I had it on display working for a day, I managed to get the fan mounting holes to line up with the slots on the back, so didn't need to make any extra holes

Best of luck with the restoration,

Lloyd.

PS: the heat resistant glue I mentioned is Loctite 4981, only thing is it's £26 for a 20g bottle!

[Nicklyons2]

For me I'd stick (sorry no pun intended) with the traditonal/old type araldite which takes around a day to set and the old type is certainly good up to near boiling point. The other advantage of this is that to a limited extent it will accept colour without compromising its strength. I've mixed in a few drops of the Humbrol enamel paint of an appropriate colour whilst mixing the 2 parts of the Araldite. This renders it even more invisible if it oozes or fills in the serrated edges you get with chipped or broken Bakelite. I would reinforce from the inside as well though.

[Stubble]

Thanks for the advice chaps

I’ll change the resistors as soon as I have some and in the mean while I will attempted a repair on the case, I’ll try my luck with the old style araldite and fibreglass reinforcement on the inside, I have never had much luck with super glue but will use this to re-build the speaker grill.

I don’t have a back cover so that’s another challenge; I can install a fan in the cover I construct for it to keep the heat levels down.

Much appreciated
Lee

[Stubble]

Hi all

Been a few months now since a last up-date on this set.

I have now completed the electronic work and replaced all the waxies and some resistors.

Glued the many parts of the case back together and reinforced with fibre glass, there are some cracks and gaps to fill in some time but I very happy with the results so far.

[Stubble]

Ho, just like an old car, the raster has started cogging slightly only noticeably with the test card, top and bottom shrinking away by about 3mm and then back again, what could that be?

The only caps that may need changing are the three electrolyte’s across the HT power supply.

Lee

[KeithsTV]

I'd suspect C25 the 16uF cap. I had a similar effect on my TV22. I just bridged a 10uF cap across it which cured the problem.

Keith

[Stubble]

Bother

Changed c25 the 16uF electrolytic also re-stuffed c27/26 the 60uF/250uF can as it was very hot.

Now the frame is very jittery top and bottom, what have I done?

It was going all too well!!!!!!

[Boom]

Originally Posted by Stubble

R21 180K reading 107K

Are you sure about this? My understanding is that these type of resistors go high not low in value.

[Heatercathodeshort]

The symptoms displayed are typical of the early stages of blocking oscillator transformer failure. It may well be suffering from 'Green Spot'. I know it's difficult on the TV22 but often giving the winding bobbin a squeeze with your fingers produces changes in the display. Height and linearity pots with hot spots can also give odd symtoms. A scope hooked onto the oscillator output may prove where the disturbance is coming from. I would agree that the resistors would tend to go high rather than low but is they are 20-25% of their value, should be fine in the TV22. Of course one could be 'iffy', intermittent or very noisy. J.

[Ed_Dinning]

Hi Stubble, not a total disaster as they are easily re-wound (as they often fail!)

Ed

[HamishBoxer]

The frame tx certainly fails normally with frame collaspe O/C.Yes i have had reses go low as well as high.