My Christmas present - Bush TV22

[mark pirate]

I have just collected my Christmas present, a very nice TV22
Condition wise, it is in excellent condition both inside and out. The rubber wiring is still supple, even round the dropper.
A close inspection revealed the set is totally original with no replacement components, although a couple of valves have been replaced and the top cover for the LOPT enclosure is absent, as is the original mains lead.
It is covered in an undisturbed blanket of dust, just as we like to find them

A quick check with my meter showed continuity of both fuses and the CRT heater.
I hooked up my B&K 470 to the MW 22-16 CRT and checked for shorts and emission, I was amazed just how quick the tube woke up!
Emission is excellent, It has never been converted for ITV, so I am sure this set has seen little use.
Unusually, all the back screws are present, and the often broken focus lever is fine.

I intend to snip out both the mains filter cap and hum reduction cap and hook it up to my variac tomorrow, for the amusement of my guests....

Mark

[Ian - G4JQT]

Excellent present!

A picture by Easter?

Good luck with a restoration.

Ian

[mark pirate]

Hi Ian, Not to sure when I will get round to restoring it, I have a TV12B that should be tackled first!

I am pleased that it is the later version with the EF80 RF deck, I have previously restored my earlier version, and it performs very well indeed.

I am just hoping the LOPT and blocking TX are ok, both were shot in my TV24

Mark

[line sync]

Your not supposed to open your presies until christmas day.
You have a nice example there mark with a very good back cover as well.

Robin

[mark pirate]

I removed the chassis from the cabinet to get a better look, the blocking tx checks fine, the voltage taps were already set for 240v and the mains switch showed continuity. So a correctly wired mains lead (neutral to chassis) was plugged in to the variac and power applied.

At around 130v I could see the valves beginning to glow, I then noticed the audio output valve was not lit. A closer inspection showed a couple of the EF80's in the RF deck were also not lit, I then remembered those nasty heater decoupling caps have a habit of going short circuit
A quick check on the underside of the RF deck revealed two were S/C, these were snipped and power was applied.

This time all was well with all valves lit, at around 180v the audio stage came to life. But not a sniff of EHT, even at full mains
Hopefully due to duff caps and not a LOPT problem.

I have made a list of all the required caps, so these will be added to my next order.

The day was saved by bringing out my restored TV22, which provided the evenings entertainment flawlessly, despite not having been used for a couple of years....

Mark

[Courtney Louise]

I *might* have a spare TX can top. Don't hold me to it but will dig around the garage...

[mark pirate]

Thanks Courtney, much appreciated.
I have been going through my capacitor stash, and already have most of the required caps and some new EY51 & PZ30's.

I may just cheat and recap the main deck and borrow the RF deck from my restored set just to get it up and running.
The worst job is to remove and recap the main tagstrip, there are a couple of caps hiding on the rear of the strip. It is quite fiddly to unwrap the component legs from the tags, but I like to do a proper job!

Fingers crossed that the LOPT is OK....

Mark

[beery]

Hi Mark,
It might be an idea to change both ECL80s for known good ones before you power it up again. If the lopty is at all rusty then it takes a lot for the LOP stage to oscillate and if it does not start up then the PL38 gets fried quite quickly.
Also a good idea to replace the frame caps early on to give the blocking oscillator transformer a better chance (though sometimes they still fail anyway whilst in use).

It is also interesting to note that although the multi-section HT capacitor usually re-forms perfectly, I have never had any joy with the 16uF cap that is under the chassis (not that it would prevent the line stge from working).

Anyway, I look forward to the next installment.

Cheers
Andy

[mark pirate]

Hi Andy,
Although the set has no signs that it has seen any damp, the top of the lams on the LOPT do have a bit of rust present.
I will take your advice on the ECL80's as I have plenty in stock, the set will not be powered up again until I have recapped the top deck and tested the valves.
I will also fit a new EY51 as I have plenty of them.

I have ordered some 0.002uf & 0.003uf caps, so will make a start on the set later this week.

Mark

[Courtney Louise]

in fairness you could just disconnect the HT from the RF deck to isolate it and ont have to swap them over for now.

Yes I have found you a can top...

Courtney

[Radio Tech]

Hi Mark

These Bush TV22 sets are very easy to service, and everything is on tag boards well almost and it should not take you too long to get the picture and sound up. Good luck with it, wanna see it working by spring.

Ken

[mark pirate]

My capacitor order has arrived, so I intend to make a start on it tomorrow if not too badly hung over after tonight's festivities

Thanks for finding that lid Courtney, I will send you a PM later.

everything is on tag boards

unfortunately this does not make it easy, Bush wound the component leads through the tags. It took me ages to desolder and replace the caps on my TV24, it is only too easy to loose concentration and solder a component to the wrong tag (been there, done that with my first TV22).

Mark

[mark pirate]

The restoration is now well underway, I started on the most fiddly job first.
The tag board on the underside of the top deck has to be unscrewed, several wires have unsoldered from the bottom tags so the board can be flipped up to gain access to the components mounted on the rear.

there are three capacitors and four resistors hidden underneath, there were two resistors that needed to be replaced as they exceeded the 10% tolerance.
Due to the smaller size of the new capacitors, these were moved to the front of the board, this will make life easier if replacements are ever needed.

The chassis was truly filthy behind the board, it took a fair bit of effort to remove all the baked on muck, the board itself was cleaned with WD40 on cotton buds.

The old caps were replaced one at a time with the values facing out.
All in all, this job has taken up most of the day!
It is a slow process to remove the old components, as these are wound through the tags. A very good practice, but a pain to remove

I hope to finish the top deck over the next couple of days, then get started on the RF deck.

Mark

[mark pirate]

Today saw more progress with the set, I finished cleaning and recapping the underside of the top deck.
I had to fit two 0.1 caps in parallel as I did not have a 0.2uf in stock, the 16uf electrolytic had bulged at one end and read 230uf on my meter

With the underside finished, I cleaned and recapped the side tagstrip and the surrounding chassis, renewed the single cap on the other side and made a start on the top of the chassis.

I replaced the mains filter cap with an X2 of the same rating as the original, and started carefully cleaning round the line output stage.

The only sign of any previous attention are two Tungsram valves (PL38 and a ECL80). I need to order a couple of resistors that are out of spec, but tomorrow I intend to finish the main chassis and make a start on the receiver chassis.

Mark

[mark pirate]

I have now finished the main chassis, it took a good couple of hours to clean it up to how it should look. The focus assembly was covered in semi dried grease and was stiff to operate, a good going over with WD40 and cotton buds got it clean and smooth to operate.

The 2uf cap on the scan coils was shot, however the one removed from the underside tests fine for both capacitance and ESR, so this was fitted rather than a modern one.
It also has the date of manufacture as May52.

I have now started to recap the RF deck, I forgot how fiddly these can be
There are about 25 waxies to replace, so should keep me busy for a while...

Mark

[KeithsTV]

Yours must have been built a month or two before mine as the 2u caps on mine were dated June 52. I replaced both with film caps.

Keith

[Courtney Louise]

I would have got first light from the main deck before even looking at the RF deck. Just my £0.02p

[mark pirate]

Yours must have been built a month or two before mine as the 2u caps on mine were dated June 52. I replaced both with film caps.

Hi Keith, Actually there are various dates on the caps in this set. May 52 is the newest, the Earliest is Feb52.
With the exception of the main smoother and one of the 2uf caps, the rest were absolutely shot, two of the 0.001 heater decouplers in the RF deck were dead short!

I would have got first light from the main deck before even looking at the RF deck.

Normally I would do, but this being the sixth one of these sets I have restored, it just made more sense to shotgun all the caps once I had established that all the major parts were good.

As I am waiting for some 0.003 caps to arrive to finish off the RF deck, I decided to test the valves.

I am certainly glad I did, the PZ30 is critical in these sets, as it uses one half as the HT rectifier and the other half as a boost diode.
Anode 1 tested OK, but anode 2 showed virtually no emission at all!
So the HT would have been virtually non existent. I did notice that the width control was at maximum, a sure sign that this set was probably used until it failed due to lack of HT.

Luckily I had one that tests good, all the rest test fine.
I also see that the EY51 is also a Tungsram replacement, so hopefully good.

Mark

[mark pirate]

I had a visit from a friend who saw the set before I had started the restoration.
He asked if I had got it working? Well as most of the caps have been replaced on the receiver, I decided to power it up.

Well the good news was the set powered up fine, both HT and EHT were spot on.
I connected up the Aurora and with a bit of fiddling, up came a pretty good picture

Although the audio section is fine, I could not get any sound, this turned out to be a poor contact on a valveholder and the sound came booming through.

The only problem was the frame hold was very critical, replacement of the ECL80 frame amp/oscillator cured this completely.

I placed a large order of capacitors with 'Just Radios' in Canada on Sunday, I was amazed when they turned up this afternoon!
So the remaining caps will be fitted tomorrow and the electrical restoration can be completed.

I will then get on with the cabinet, so hopefully the set will be finished on Sunday.

Mark

[beery]

The picture looks fantastic

Good tube and good lopty - result!

Cheers
Andy