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Old 15th Jan 2022, 6:03 pm   #1
Andy - G8MNM
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Default Bush TV62/BK 465 CRT Tester

Hi, I have two Bush TV62's which I need to determine the state of their respective CRTs. There is too much work required to get them to any sort of functioning state without knowing what state the CRTs are in.

I have a BK 465 CRT tester (from the USA). I can run it off my 110V supply. I will have to add an Octal CRT base connector so I can attach it to the CRT.

Anyone got any experience of using the 465? I have never used it since buying it quite a few years ago from the uSA.

Any help would be much appreciated. For info I am an electronics tech and cut my teeth on old valve equipment and TV's back in the 60's. Just almost finished a PYE V4 restoration.

Andy
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Old 15th Jan 2022, 7:03 pm   #2
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Default Re: Bush TV62/BK 465 CRT Tester

It will give you a good idea what condition they are in with respect to emission.
Would also be worth checking the mains transformer in the 645 as mine had multiple mains input tags.
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Old 16th Jan 2022, 1:56 pm   #3
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Default Re: Bush TV62/BK 465 CRT Tester

I looked through the US Tube data and found a similar CRT to the one fitted in the TV62. The TV62 has a AW36-21- 14", 90 degree ,electrostatically focused tube.

The closest US type was the 14WP4. I used my variac to power the BK tester and set the heater voltage using my Fluke as the BK meter was reading under - showing just over 5V when the correct reading should have been closer to 6.3V

I set the G2 Voltage as per the guide (zero G1 Voltage for this test) and the CRT tested very good.

I did the life test (G1 cutoff Voltage - Cathode emissive material condition) and that result was good too, a gradual fall off in the meter reading when the G1 potential was adjusted within the parameters 22-72V.

The tube base is loose, so needs gluing. In the past I have used Araldite, but not sure now that Araldite is the best adhesive to use in this setting.

Any suggestions please!

Andy
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Old 16th Jan 2022, 7:27 pm   #4
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Default Re: Bush TV62/BK 465 CRT Tester

Quote:
Originally Posted by Andy - G8MNM View Post

The tube base is loose, so needs gluing. In the past I have used Araldite, but not sure now that Araldite is the best adhesive to use in this setting.

Any suggestions please!

Andy
There are various opinions about attaching a CRT base. Personally I like to use an 'impact adhesive' in UK like 'Evo Stik'. Impact adhesives don't set solid like Araldite and retain a certain amount of 'give'. This allows expansion as the CRT glass warms up. Araldite and similar two-part adhesives set solid and there is a possibility of thermal stress and cracking the CRT neck. The risk may be small but I've never had problems with impact adhesives.
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Old 16th Jan 2022, 10:42 pm   #5
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Default Re: Bush TV62/BK 465 CRT Tester

Hi.
I use a very light smear of Araldite Rapid. The rapid version doesn't set as hard as the slow setting type.
I find you only need a very small smear and it's fine.
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Old 17th Jan 2022, 12:01 pm   #6
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Default Re: Bush TV62/BK 465 CRT Tester

Thanks guys for help with the glue.

I have adhesive which is made for gluing glass. It stays a bit flexible when set. I may try that. I don't have and Araldite rapid and would probably find it difficult to find locally. I will take a look next time I am at Intermarché in town.

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Old 17th Jan 2022, 12:29 pm   #7
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Default Re: Bush TV62/BK 465 CRT Tester

The Poundland two tube adhesive is brilliant for dealing with loose bases and top caps. It costs only £1! Picture attached for recognition. I have no connection with Poundland. John.
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Old 18th Jan 2022, 9:49 pm   #8
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Default Re: Bush TV62/BK 465 CRT Tester

Hi
Fired up my TV62 today as its now in the house. Its been off for two weeks, came up perfectly with no adjustment required. Still need to get the back and a line stage screening can though.
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Old 19th Jan 2022, 11:57 am   #9
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Default Re: Bush TV62/BK 465 CRT Tester

Hi Trevor,

So looking good for your TV62!

I have one/two on the bench at the moment.

One I bought and it turned out to have all its valves pulled, filthy condition inside along with rust. The tube tests very low too!

The other was given to me by a forum member some 7 years ago.
All the waxies had been replaced but not much life when powered up.

I have replaced rotten rubber covered wiring, out of spec resistors in the line oscillator,line output stage, dodgy looking PL81, 2 x low emission PCF80s and several EF80's.

So from an initial 5KV the EHT has now risen to just over 10KV (measured with tube final anode dis-connected - due to difficulty making contact with the connector when it is connected to the tube.

So now I have got first light (I checked the tube condition first with my BK tester before embarking on too much work on the set).

So now a reduced height raster with no suggestion of any picture content or sound.

The tuner and IF deck look as though the IFs have been twiddled at sometime in the dark and distant past, (compared to the ones on the other TV62)- certainly before the person that re-capped it and kindly gave it to me.

I decided to swap the tuner/IF units between sets and work on the 'manky' one, replace the waxies and rotten crumbling rubber covered wiring and fixing the faults.

So that is where I am at right now. The soldering iron is hot, so on with he job.

I think it unlikely that I will do any work on the other TV62 as it will need so much work and has a very low emission tube - there are other sets that are more important on the to do it pile.

I may therefore, be able to help you out with a back/better cabinet when I decide what to do with it.

The only issue is that I am in SW France and you are in Scotland!

Strangely both sets are missing the EHT screening cans!

Some pics of the manky unit ,a couple of the recapped unit from the better set and a pic inside the good set.

Andy
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Old 19th Jan 2022, 11:58 am   #10
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Default Re: Bush TV62/BK 465 CRT Tester

A few more pics of the TV62.
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Old 24th Jan 2022, 3:18 pm   #11
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Default Re: Bush TV62/BK 465 CRT Tester

I have finally got a display on the TV62 after much work - out of spec resistors in all sections - including the tuner unit.

Cleaned switch connections in the tuner too.

All valves checked and any suspects swapped out.

The CRT tests as very good on my BK tester- emission and cutoff voltage.

I have put my Pye V4 next to it for comparison as the contrast on the TV62 is not so great. I can get a good bright display but not with good contrast.
Both sets fed with the same signal level - from a distribution unit.

The contrast control works but only seems to overload the signal stages/video amp - see pics with the contrast control advanced and fully advanced. At which the point the picture disappears and the sync is also lost.

Any suggestions? Could it be that although the tube tests good that it could be the cause of the poor contrast? Or maybe something else?

Andy
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Old 24th Jan 2022, 5:05 pm   #12
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Default Re: Bush TV62/BK 465 CRT Tester

Does it have an interference limiter control next to the contrast like the TV32? Make sure it's turned fully anti-clockwise.

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Old 24th Jan 2022, 5:40 pm   #13
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Default Re: Bush TV62/BK 465 CRT Tester

It's difficult to compare the Pye V4/VT4 with the Bush. The Pye has a grey Perspex filter screen helping to give a better black with less reflections.
I presume the Bush is dropping the correct 6.3v in the heater chain. John.
PS Picture one with normal contrast setting. 2 with contrast advanced to video overload. 3 with contrast reset to normal and limiter 3/4 advanced.
Tube is a non aluminised AW36-21.
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Old 25th Jan 2022, 10:27 am   #14
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Default Re: Bush TV62/BK 465 CRT Tester

Hi.
You really cannot compare the two sets. The PYE has APC and always has good black level. Compare like for like. Mine is good but beside the V4 or VT4 I have I prefer the pictures from the Pye due of course to the Bush's inferior black level. From my hedghog and aurora feeding one set the contrast on the TV62 is about a quarter from minimum for the best results it starts to overload above half way, interference limiter fully anticlockwise obviously.
One thing is to check all components around the video amplifier and anything getting close to the tolerance maximum I'd replace. Also check the network to the CRT cathode
Have fun.
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Old 25th Jan 2022, 10:46 am   #15
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Default Re: Bush TV62/BK 465 CRT Tester

You'll notice that on Andy's pictures there is a lot more ambient light than on John's pictures, that does make a difference to photos.
I'd say Andy your TV62 is a little washed out, check that interference limiter, ( I normally disconnect the full circuit) change C48 from. O5uf to 0.1uf and R51 from 270k to 100k. Feed to CRT Cathode. You can dispense with these components but it's advisable to run the CRT heaters from an isolated heater transformer and connect one heater pin to cathode via a 1 m resistor.
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Old 25th Jan 2022, 11:01 am   #16
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Default Re: Bush TV62/BK 465 CRT Tester

The Bush does give a very bright picture. It's a very good example of one of these 60 series. John.
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Old 25th Jan 2022, 3:12 pm   #17
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Default Re: Bush TV62/BK 465 CRT Tester

Hi Guys, Thanks for the input.

John - Heater voltage is 5.02 V (AVO 8)

I hooked up the heater to a DC supply and ran it at 6.3 Volts and it was taking 350mA (the current reading remains stable) in operation.

Trevor - I will make the circuit changes you recommend - thanks.

You have a PM. Is your email address still the same? I sent you an email, but there were reported issues delivering it.

Peter - it does have an interference limiter, it is turned right down, I shall disconnect it as suggested by Trevor.

Any idea where I can get a small heater transformer from?

I shall keep you informed as to progress. The other TV62 is a non starter as the tube is as flat as a pancake!

Andy
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Old 25th Jan 2022, 3:33 pm   #18
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Default Re: Bush TV62/BK 465 CRT Tester

It should read 6.3v with the correct mains tapping. A partial heater short is likely but that usually gives a reading of around 3-4V. Applying 6.3V from a transformer results in a very bright heater. Unfortunately a very common fault with Mullard Duodecal based tubes. John.
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Old 25th Jan 2022, 3:48 pm   #19
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Default Re: Bush TV62/BK 465 CRT Tester

I forgot to mention that all out of spec resistors on the IF deck have been changed - all the big ones on the tag strip near the video amp in particular.

One had doubled in value!
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Old 25th Jan 2022, 5:07 pm   #20
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Default Re: Bush TV62/BK 465 CRT Tester

John,

I connected a PCF80 I had near to hand in place of the tube heater and got around the expected 6.3V so there is some degree of short in the tube heater. It didn't look overly bright when I ran it at 6.3V of the bench supply.

I have found a small transformer (from a South African) mains adapter I picked up at the recycling centre. I connected it up to the same PCF80 and am getting around 6.2V across the heater.

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