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CTV The Shunt Stabiliser in a 1st Generation Colour Receiver...

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Colour Television

Last Post by Captain Peacock 9 months ago

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Nuvistor

(@nuvistor)

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@irob2345 I dont think there is a problem double checking that the voltages are correct, normal practice on any circuit that are dependant .

Frank

Posted : 15/03/2024 12:45 pm

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Marconi_MPT4

(@marconi_mpt4)

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There are several shunt stabiliser configurations used by different manufacturers and in all cases their set up procedure should be followed. Back in the eighties we still had a few B&O 3200 sets in for service and irrespective of the service required the policy was always to check stabiliser operation. To be fair I don't recall ever having to replace a PD500. Double checking settings is always a good idea.

There is a good analysis of several shunt configurations in Hutson Colour television Theory chapter 17. It was a required text for C&G CTV course. Attached section 17.3 which is relevant to Philips implementation. Setting the boost voltage when displaying a normal locked picture normalises boost reference for the shunt stabiliser allowing it to operate over the full range of conditions encountered, so the actual PD500 operating point at zero beam current is relative.

Posted : 18/03/2024 11:59 am

Captain Peacock

(@captain-peacock)

Posts: 28

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@irob2345

Good point! But according to the service manual, that was the correct order of setting up the boost and shunt bias on a SS G6. Ffrom what I can remember, I used set up the boost voltage first, then the shunt bias afterwards.

Interesting (and logical) that the 3rd harmonic tuning had to be checked first: I don't ever recall adjusting it as we never carried an oscilliosope in the car as they were too expensive. Not sure we even had one in the workshop!

But there again, it was over 45 years ago I last worked on a G6!

Posted : 19/03/2024 11:58 am

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