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Old 29th Nov 2020, 6:08 pm   #1
dragonser
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Default Removable TV PCB's for Service

Split from this thread

https://www.vintage-radio.net/forum/...d.php?t=166433

Cheers

Mike T


Hi,
that is most impressive !
on a similar subject,
Wasn't it Alba ? who made a 405 line television with pcb's that could be unplugged and sent back for service ?
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Old 29th Nov 2020, 7:18 pm   #2
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Default Re: Removable TV PCB's for Service.

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Wasn't it Alba ? who made a 405 line television with pcb's that could be unplugged and sent back for service ?
Yes, The Alba T655 17" table model c1958. two panels, timebases and IF.
Very popular model. You could return the panels to Alba's 'Package Service' dept. They would service them and return for 35/- [£1.75] or of course repair them yourself. Ideal for rental. John.
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Old 29th Nov 2020, 7:34 pm   #3
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Perhaps you could start a "factory refurbished" panel service, put Interlace to work!
It's surprising how quickly you can go orf some people.
I suggested your idea to INTERLACE but if adjustment to an ion trap is not part of the deal his enthusiasm quickly leaks away in a similar manner to EHT through a Visconol. Cheers and thanks all. John.
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Old 29th Nov 2020, 7:48 pm   #4
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Default Re: Removable TV PCB's for Service

Hi,
thanks for letting me know which make and model it was....
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Old 29th Nov 2020, 9:31 pm   #5
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Default Re: Removable TV PCB's for Service

BRC/Thorn had plugin panels for the 2000/3000/3500 chassis' that were designed to be interchanged.
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Old 29th Nov 2020, 9:42 pm   #6
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Default Re: Removable TV PCB's for Service

Do i seem to remember the philips 1768 had a fully pluggable loptx, don't know if that counts!.
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Old 30th Nov 2020, 10:49 am   #7
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Default Re: Removable TV PCB's for Service

Everyone's least favourite recent-ish chassis, the Sharp CS, was designed to be revolutionary in thet it had a very small PCB with extensive use of SMDs (when few of us had rework stations) that was designed to be sent back and exchanged when it went wrong.
Of course this was a disaster. A new board was very expensive, so holding one in stock was a non-starter for most of us. The customer had to wait while you sent back a faulty board and in exchange received a high-mileage Friday afternoon board with a whole thirty days' guarantee for a bargain £85. It went wrong three months later and, well, you can guess the rest...
So we had to repair them and what a pile of junk they were. A common fault was LOPT and transistor, jungle IC, DC coupled line driver components, capacitors, class D audio IC and a hanful of diodes. Yes, a typical fault on one TV!
I believe a local branch of a national chain were unlucky enough to offer a five-year warranty on these. When the last one emerged from the periood the engineers went out for a celebration meal.
Oddly enough, a nice conventional chassis followed the CS.
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Old 30th Nov 2020, 12:29 pm   #8
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Default Re: Removable TV PCB's for Service

Korting where every panel plugged in and could be fitted on the back of the mummyboard for easy servicing, one of the best IMHO.
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Old 30th Nov 2020, 1:17 pm   #9
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Default Re: Removable TV PCB's for Service

The Philips 1768 did indeed have a very complex inverted plug in transformer and the same went for the tuner/control panel but was not designed for 'Package Service', more a case of making it simple to carry out general service repairs.

Alba continued with PS into the T766 series, a very modern looking super slim table model with the short neck Mullard AW43-89 CRT and the very odd two position tuner, harking back to the Bush TV24C series.

A number of manufacturers including the Philco Condenta series of 1960 employed plug in Lopts but as mentioned it was a gap of six years between the Alba T766 and the Thorn 2000 before fully plug in panels were resurrected.

Alba developed some interesting features. John.
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Old 30th Nov 2020, 4:51 pm   #10
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Default Re: Removable TV PCB's for Service

Most soviet TVs had modular chassis made of multiple PCBs, it was a big advantage because chassis would be shared across multiple manufacturers so it simplified logistics a lot, important in a developing country.

It also meant that it was easier to pull them apart and fix them before the factory defects burnt your house down. I'm thinking about the colour valve transistor hybrids in particular.
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Old 1st Dec 2020, 9:28 am   #11
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Default Re: Removable TV PCB's for Service

The Thorn 2000 was a great idea, but the problem came when the panel swappers decided the edge connectors were causing intermittent faults and ran solder across the tracks. They connected very well as the socket's claws opened to grip the thicher track. Put in a normal board and of course they didn't grip properly.
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Old 1st Dec 2020, 10:10 am   #12
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Default Re: Removable TV PCB's for Service

The Philips G11 was very modular, as were a lot of Grundigs of the same era. I had a Grundig SuperColour 8632 which also had an unpluggable LOPTx.

I seem to remember that the Singapore(?)-made Philips KT2 14" portable also had loads of plug-in modules.
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Old 1st Dec 2020, 11:01 am   #13
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Default Re: Removable TV PCB's for Service

The so called Decca 'Professional' series and the DR122 also had plug in LOPTs. They needed them..J.
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Old 1st Dec 2020, 11:32 am   #14
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Default Re: Removable TV PCB's for Service

I still have a KT2 knocking around. Very little trouble with them, but I do remember replacing a chroma module on one while they were still available. The biggrest problem were the push-buttons disintegrating and the tripler could arc over.
As Mike says, the Kortings and Grundigs had modules that could be plugged into the rear of the board making servicing easier, though as usuual the sets that DID need this facility didn't have it!
Oddly enough, there are firms that are now advertising board repair services for LED sets - handy if you don't have SMD equipment. However, some offering BGA repairs often just heat the board up and hope for the best instead of reballing.
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Old 1st Dec 2020, 12:08 pm   #15
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Default Re: Removable TV PCB's for Service

The Granada/GEC sets I use for rental had all swappable panels, the power supply had a few extra leads but all the others just unplugged. I used to carry a box of tested panels round with me, I also used to buy damaged/scrap sets from my supplier just for the panels.

This considerably reduced service times, the only problem being that after quite a number of years with just these sets out, when they came to an end I had to start learning how to repair TVs again!

Peter
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Old 1st Dec 2020, 5:26 pm   #16
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Default Re: Removable TV PCB's for Service.

Quote:
Originally Posted by Heatercathodeshort View Post
Quote:
Originally Posted by dragonser View Post
Wasn't it Alba ? who made a 405 line television with pcb's that could be unplugged and sent back for service ?
Yes, The Alba T655 17" table model c1958. two panels, timebases and IF.
Very popular model. You could return the panels to Alba's 'Package Service' dept. They would service them and return for 35/- [£1.75] or of course repair them yourself. Ideal for rental. John.
Here are a few photos of an example of the T655. The panels on this one of mine have certainly seen some service...

Steve
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Old 1st Dec 2020, 6:24 pm   #17
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Default Re: Removable TV PCB's for Service

Yuk! I have seen a lot worse. They should clean up OK and with care the printed circuit will be serviceable.

Odd that the Alba T655 was an advanced design but they did not incorporate AGC. Separate pots were provided for adjusting the gain on Band 1 and 3 . For the cost of a couple of resistors and a cap, it would have made the chassis nicer to handle.
The pot switching and extra preset must have cost more than designing in simple mean level AGC.

I don't think the final Alba TV chassis, the crazy 800900 series was specifically designed for the PS scheme. It was a very good dual standard design with high gain but the terrible 'ratchet' VHF tuner was a mechanical disaster and from then on Alba decided to pass their TV production over to Philips.
I guess most of those panels were serviced in the workshop rather than using Alba's return service. What a doddle! Even easier than the GEC BT302. John.
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Old 1st Dec 2020, 7:22 pm   #18
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Default Re: Removable TV PCB's for Service

Rediffusion were very quick off the mark with their modular TV receivers.

Both their wired & off-air 405 - line Sheerline models had replaceable plug-in PCB.s.
The edge-connectors were awful, and tended to track across the print & or the actual connector, especially on the timebase panels.

We used to repair our own PCB's back at the local workshop, so that the field service engineers could cram in more service visits.

Rediffusion continued with the modular construction on their MK1 colour hybrid models. I built a jig using a TV with a damaged cabinet, & cut holes in the sides for easy access, & fitted a built-in EHT meter as well as various probe points on the wiring loom. I've no idea how many panels I repaired, but it certainly ran into three figures!

David.
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