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Saga of a Philips K12 Chassis..still ongoing!  

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PaulGoggo1
(@paulgoggo1)
Trusted V-Ratter Registered

I recently acquired a Philips Goya 965 from Germany. Its a 26" model with Remote control. High quality sound is possible (when I get the speaker sorted). Its a smart looking set- no teletext (but a board could be fitted).

On first examination it was found that the Backup battery (NiCad type) had severely leaked and caused damage to the PCB tracks on the Tuning control panel. This is why there was no LED display, no tuning with no other functions. Once these were repaired, the set functioned (after a fashion) but the focus was well out. The CRT tested well with good emission (its a A66-540X-30AX type). The focus control had no effect of course!

Stripping the focus module down revealed a slider contact stuck at one end. Its a thick film type which can be dismantled with care. Lots of nicotine stains were present too.( in fact the set was heavily contaminated with nicotine and took some cleaning). Any way a bit of a clean up around the slider area, and checking the three A1 sliders in the same assembly, it was reunited with the set.  focus was then adjustable and looked good.

The set was left on soak for a short time,  I just decided to cycle through the test patterns on my Generator to check all was well,when the red Raster suddenly disappeared! Fearing the CRT has gone to TV Heaven, I quickly confirmed that all 3 heaters were alight and put the tube tester on to be sure. All was ok with the CRT, voltage checks however revealed something was not well with the red channel. As these sets have lots of thick film modules (3 on the CRT base for the RGB amplifiers) a quick swap over from the green channel made no difference. Clearly further back, so dragged out the trusty scope and found no Red drive to the CRT base or the input to the Red amplifier.

Checking the RGB matrix Thick film unit on the main chassis revealed no red output there either. However the RY-BY-GY signals were present at the inputs so this module had a problem. There are very few parts on this module, mainly a TDA 2771 IC which I don't have (which could be changed). So no red for the moment. Unless anyone has a module or a TDA2771 chip?

The other fault which cropped up, is a intermittent fast rolling picture, the frame hold having little effect. If you cycled the mains to the set, it sometimes would come backed locked and then off it went again. Not investigated this fault yet as I was spending time chasing the missing red!

So the saga continues. Anyone had much experience with this chassis? How common are they in the UK? never seen one before. All plug in modules (Thick film type) and a large daughter board which swings out like a car door for easy access. There was a circuit in a envelope inside the set luckily!

Philips Goya 965 K12 Chassis
Matrix RGB Module
Matrix RGB Module 2

Paul

 

 

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Posted : 16/02/2020 11:29 pm
ntscuser liked
sideband
(@sideband)
Famed V-Ratter Moderator

There were a few variants of this chassis in the UK but the most common was a 26" which I think was 26K797 (something like that....don't quote me)! Lovely set with Hi Fi sound although mono, made in Sweden. There was also a 'video centre' which consisted of a 26"TV with combined 12" monchrome monitor and a VR2020 VCR built into the top. Finally there was a projection set (the model number 60K1201 rings a bell but again don't quote me). 

When I was at Philips, I used to enjoy repairing these....mainly because no-one liked them.......too complex! Actually they were very reliable and only a dozen or so passed through my hands. I never saw the projection set or the video centre other than demo models in the video showroom.

It's well over 30 years since I saw inside one of these and apart from the odd dry joint, shorted diode, tuner IC's and thick-film RGB modules going faulty, I don't remember any major faults.

They were much more common in Europe.

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Posted : 17/02/2020 8:24 pm
ntscuser liked
Red_to_Black
(@red_to_black)
Noble V-Ratter Registered

One fault sticks in my mind on this chassis, a loss of green ! this turned out to be a contaminated printed spark gap on the crt pcb (it is part of the printed circuit board) so worth a look/clean here (I used a fibre pen to clean it with).

I would have expected the green gun to be flooded due to this myself, unfortunately it was such a long time ago I cannot remember the reason it acted the way it did.

I remember this particular fault as this set came as a trade repair from a Philips dealer! They too had tried swapping hybrids about etc..etc.

To be fair to them they hadn't had much to do with this chassis either, although I myself had only ever seen a handful.

They were either quite rare here and/or very reliable.

I thought they were quite a nice chassis/set myself.

Ps. I only ever saw one projection set ever, every other one I saw was a 26" ' hi- fi' model

"This is my multimeter. There are many others like it, but this one is mine. My multimeter is my best friend. It is my life. I must master it as I must master my life. Without me, my multimeter is useless. Without my multimeter, I am useless."

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Posted : 17/02/2020 10:08 pm
Cathovisor
(@cathovisor)
Illustrious V-Ratter Registered

When do these sets date from? Because I vaguely remember the parents of someone at school in the late 70s having a Philips set that proudly wore the badge "Hi Fi" on the front... 

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Posted : 17/02/2020 10:46 pm
Red_to_Black
(@red_to_black)
Noble V-Ratter Registered

I think it was about 1978/9 looking at my model listings, although this only gives the year the manual was first produced and we don't know the production run length with any certainty, the sets could have been produced maybe a year before the manual was first published.

"This is my multimeter. There are many others like it, but this one is mine. My multimeter is my best friend. It is my life. I must master it as I must master my life. Without me, my multimeter is useless. Without my multimeter, I am useless."

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Posted : 17/02/2020 11:03 pm
Jayceebee
(@jayceebee)
Noble V-Ratter Registered

Never ever seen one of these but looking at the circuit from the library (Yes, I checked there first Chris 👍) the TDA2771 IC seems to perform an auto greyscale function. The red channel has an extra resistor R609 in the feedback path. I can't quite tell if it's 6.8K or 68K but would be worth checking together with the A1 setting which can be critical for correct operation.

John.

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Posted : 17/02/2020 11:05 pm
crustytv
(@crustytv)
Vrat Founder Admin

Another service manual for the K12 chassis just uploaded to the library, it's a full manual this time and much clearer. Here's a snippet of the relevant area, R609 is a 6.8K

matrix

 

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Posted : 17/02/2020 11:33 pm
Cathovisor
(@cathovisor)
Illustrious V-Ratter Registered
Posted by: @red_to_black

I think it was about 1978/9 looking at my model listings, although this only gives the year the manual was first produced and we don't know the production run length with any certainty, the sets could have been produced maybe a year before the manual was first published.

That would fit with my memory of the time, about '78. Fancy that - I've seen a rare telly 🙂 

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Posted : 18/02/2020 5:33 am
PaulGoggo1
(@paulgoggo1)
Trusted V-Ratter Registered

Hi Chaps

Thanks for all the replies. Interesting to hear it was in the UK for a short time.

 I will check the suggestions here and return shortly!

Thanks

 

Paul

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Posted : 18/02/2020 9:26 am
PaulGoggo1
(@paulgoggo1)
Trusted V-Ratter Registered

@crustytv

Hello

Am I able to access the Manual library here for the Manual for the Philips K12?

Thanks

paul

 

ReplyQuote
Posted : 18/02/2020 9:30 am
crustytv
(@crustytv)
Vrat Founder Admin
Posted by: @paulgoggo1

Am I able to access the Manual library

Hi Paul, that's due to the access threshold set for when a member reaches "Active Vratter" status.

I would gently and politely recommend members without access, familiarise themselves with the data library access problem thread. Basically for a number of years now it's been a symbiotic relationship. If folk like Vrat, what it offers and stands for, they should support the site by posting regularly, thereby helping the community grow. Help others with advice on their threads, as a result of this a members ranking will soon rise, then the benefits come. 😎 

However, as a goodwill gesture Paul, I have fast tracked your access. You should now find you have access and can download the manual. 👍

Crusty's Collection: Read the repair blogs
Crustys Youtube Channel: If you want to follow me on Youtube, please consider subscribing

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Posted : 18/02/2020 10:29 am
PaulGoggo1
(@paulgoggo1)
Trusted V-Ratter Registered

@crustytv

Hello

That's very kind of you. Much appreciated. I will make sure that there are regular contributions to this forum!

best regards

paul

 

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Posted : 18/02/2020 2:25 pm
crustytv liked
colourmaster
(@colourmaster)
Reputable V-Ratter Registered

Hi, I've just realised that you say that your set is fitted with a 30AX crt, it therefore can't be a K12 as they are fitted with a 20AX crt. It must be a different chassis. I have a K12 which is fitted with a A66 510x.

Regards. Gary. 

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Posted : 18/02/2020 2:39 pm
Jayceebee
(@jayceebee)
Noble V-Ratter Registered

What a shame there is no diagram for the U410 module, obviously just an exchange item. If there had been I would have had no qualms removing the components and checking the film resistors, must be worth changing the electrolytics and reflowing the IC pins at least but great care is needed not to stress the solder pads.

It's certainly a complex set bit I have to say the way Philips lay out their diagrams makes it look worse than it probably is but of course I was spoilt in the manuals department working for Thorn.

John.

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Posted : 18/02/2020 8:44 pm
crustytv liked
Red_to_Black
(@red_to_black)
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Posted by: @jayceebee

It's certainly a complex set bit I have to say the way Philips lay out their diagrams makes it look worse than it probably is but of course I was spoilt in the manuals department working for Thorn.

To be fair John it is not really any more complex than the later K30, it was very much a definite early ancestor of the later K30, although made in Sweden.

The way it works is also very K30 like, the Psu and line drive/output circuit works in a very similar way., just obviously for the 20AX crt, a different chipset and the various functions spread across a few more modules, hybrids in the mix too.

It could in fact be said to be a little bit simpler than the K30, just that the K30 had a higher level of integration.

They were very reliable too just like the K30, I don't think I ever had one of the Hybrid modules fail, although it has to be said that was then.

Philips obviously liked the basic design and carried it forward albeit much modernised, streamlined and updated for the later 30AX crt as used in the K30 series.

"This is my multimeter. There are many others like it, but this one is mine. My multimeter is my best friend. It is my life. I must master it as I must master my life. Without me, my multimeter is useless. Without my multimeter, I am useless."

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Posted : 18/02/2020 9:59 pm
Jayceebee
(@jayceebee)
Noble V-Ratter Registered

Yes, perhaps I should have said more elaborate. Certainly some strangeness with the CRT drive, it has the look that the grids are modulated but without the circuit for the RGB modules I can't really tell.

John.

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Posted : 18/02/2020 10:09 pm
Red_to_Black
(@red_to_black)
Noble V-Ratter Registered

The convergence circuits were of course more complex for the earlier tube, and there are more discrete components, plus a couple of the modules were combined function wise into one or were more logically combined to reduce the daughter board count on the later K30.

The Grid drive might have been the reason the dirty printed spark gap (to deck) on the CRT panel shut down the green drive on the set I had it is possible I suppose, as usually you get a coloured bright raster in this case with cathode drive.

It was a long time ago now and I forget, plus the fact we didn't see very many of these sets at all, I don't think I got into this chassis intricacies very much as with the more common sets from the same stable, although I did have a paper manual because a good customer of ours had two of these at the time.

The only other real faults I can recall was the usual dry joints, and one set had been damp and the EHT had flashed over damaging the field driver chip, hence us having the manual.

I wonder how many were actually imported by Philips to the UK ? it cannot have been that many.

"This is my multimeter. There are many others like it, but this one is mine. My multimeter is my best friend. It is my life. I must master it as I must master my life. Without me, my multimeter is useless. Without my multimeter, I am useless."

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Posted : 18/02/2020 10:45 pm
PaulGoggo1
(@paulgoggo1)
Trusted V-Ratter Registered

@colourmaster

Hi Gary, this chassis is a K12i apparently. this is why it has a 30AX Tube fitted. When it did work briefly before the faults set in, it had an excellent display.

Now got to get that back!

 

Paul 

 

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Posted : 19/02/2020 6:54 pm
Red_to_Black
(@red_to_black)
Noble V-Ratter Registered

The K12i does use the 30AX tube, either a A56 or 66- 540X.

I have a manual downloaded from World of free manuals I think (I don't have a link. sorry) or at least that is what the digital watermark has on it, it also shows a block diagram of module U410, this Pdf is approx. 17meg in size so I cannot even e-mail you it, too big, If Chris wants it I suppose I could upload it to the library ?

Oh! and it is German.

"This is my multimeter. There are many others like it, but this one is mine. My multimeter is my best friend. It is my life. I must master it as I must master my life. Without me, my multimeter is useless. Without my multimeter, I am useless."

ReplyQuote
Posted : 19/02/2020 7:09 pm
crustytv
(@crustytv)
Vrat Founder Admin

The K12i is already in the library, found the same source and copied it for convenience 👍 

p.s.
Unfortunately that equally does not provide a circuit for U410, just a flow diagram.

Crusty's Collection: Read the repair blogs
Crustys Youtube Channel: If you want to follow me on Youtube, please consider subscribing

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Posted : 19/02/2020 7:10 pm
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