Philips G8 (550) low gain.

[matspar]

I was lucky enough to recently find this 'delivery miles only' Philips G8.

It's beautifully clean and unmolested and even has its original stand.
As one of the most popular sets of my childhood I thought I'd have a bash at it.
Initially the set powered up with frame collapse, which was soon traced to the frame transductor which was dead short. With this replaced a nice bright raster was obtained.
Next I replaced the four green EHT tuning caps as I've read all the horror stories about what happens when these fail (and the likelihood of this occuring quite early on!)

Finally with a signal applied I have a weak and very grainy picture.
The gain is very low so based on past experiences I suspected the varicap tuner. Tapping it produced massive disturbance so I reflowed it in the first instance. No improvements were obtained. I also checked the original bit of aerial lead and isolator with a new (temporary) piece.

I fitted a brand new varicap but the G8 was then completely deaf. I've since learnt there were about three variants of this tuner which I'm told aren't interchangable and very hard to identify.

So, the questions I need to ask are -

Would anyone agree the varicap tuner is at fault or do I need to look elsewhere? Voltages to it are all present and correct along with the tuning voltage which varies normally when channel changing and when trying to tune in.

From what I've read I'm sure the tuner is an ELC1043, but there's no numbering on it apart from the small sticker shown. Is there a way of identifying it so a definite correct replacement can be sourced if need be?

Was this low gain issue ever a stock fault/is there something obvious going on here? there are no obvious clues to anything in this set. It is so clean it is like brand new. There are no dry joints anywhere and no evidence of any previous repairs.

I'm a valve man if I'm honest so slightly lost at sea here. Point me in the right direction someone please!
If anyone has scans of the factory manual they'd be willing to send me this would also be mega-appreciated.
I can only find a Newnes circuit which isn't that brilliant and doesn't cover the later models in any real depth.

Any thoughts as ever gratefully received!

[matspar]

A few more

[dazzlevision]

I'm very sure that the UHF varicap tuner fitted in all G8 models was not an ELC1043, but a much smaller unit that didn't have that sort of type number (printed on paper labels stuck to its case).

Does your set have the separate IF panel, which the separate, plug-in UHF tuner panel mounts onto, or the combined signals panel?

[matspar]

This one has the (later) combined signal panel. Here's another pic showing the varicap tuner and it's pinout, should anyone be able to identify!

[toshiba tony]

First thing I thought, a 1043 wasn't fitted in a G8.

[matspar]

I've had a few people tell me this is a 1043, and others saying it isn't! So I'm none the wiser yet.

[jayceebee]

Not a G8 expert but I’m sure Philips didn’t use the ELC1043, they must have known that it was going to be very unreliable. It does look a bit like the ELC but I don’t think it is.

John.

[G6ONEDave]

The service manuals for the 520 and 550 series both show a tuner type U6400. Not sure about the 570 series as the drawings are not labelled as to tuner type.

Dave

[greg_simons]

The elc1043 was notorious for dry joints and this avenue should be explored first with the original tuner fitted, other things to check are the rf amp in the front end and the integrity of the aerial socket and cable to the tuner. never had any weird faults agc wise, hope that helps.
Greg.
Btw, I'm as green as my lawn over your luck, most of us old techs really rated this chassis.

[dazzlevision]

Originally Posted by matspar

I've had a few people tell me this is a 1043, and others saying it isn't! So I'm none the wiser yet.

It definitely isn’t an ELC1043, which was bigger.

It is a Philips made tuner and the same size as the one fitted in the (UK designed and made) Philips 320 all solid state mono TV chassis.

[dazzlevision]

The "BY" part of the label on your UHF tuner shows it was made in the UK, probably at the Mullard Mitcham factory (Mullard has been part of Philips since the 1920s).

The 3113 108 59160 is the standard Philips 12 number factory code for a particular product, such as this tuner. If my memory is correct, the 3113 indicates it was of UK manufacture and design.

However, in the Philips spare parts system, it will have a different part number, which should be shown in the Philips G8 service manuals - there are two versions, a ring binder type workshop manual, with separate pages and a smaller book type, which I think was called the "field service manual".

In the ring binder manual that I have (with all published updates), the UHF tuner for the separate tuner module, that sits on the IF panel is part number 210 57011 (Philips Service in the UK didn't bother with the first 4 digits of the 12 number code part number) and the part number for the UHF tuner fitted on the combined tuner, IF and decoder "signals" panel is the same!

So, I think it's probably true to say that only one type of UHF tuner was fitted to the G8.

There is an AGC feed to the UHF tuner, which may cause your noisy low gain issue if the AGC crossover preset is maladjusted (R3173). Or the AGC line from the from the TBA550Q IC might be faulty. My money is on the tuner itself.

[dazzlevision]

Originally Posted by G6ONEDave

Not sure about the 570 series as the drawings are not labelled as to tuner type.

Dave

The 18" Philips 570 chassis is completely different to the G8 and uses a tuner/IF panel made by Pye, with a Mullard ELC1043/06 UHF tuner.

[stacman]

Blimey Matt looking at the condition of that TV I thought I'd gone back the the mid 70's, that both internally and externally looks in really good condition, wonder if it was a 'Friday afternoon' model and never used?
Alan.

[jayceebee]

A very good source of information about Philips tuners here.

Appears to be known as the U6.

John.

[Pfraser]

That G8 is in incredibly good condition! The styling still looks good too, all these years later.

Just in case it's needed: an article on stock faults is in 'Television' from December 1976.
https://worldradiohistory.com/UK/Tel...ng-1976-12.pdf

[chriswood1900]

What lovely condition what a find!
It looks like your tuner appears in the table about halfway down entitled:-
Overview of the Philips tuners used in UK TV sets between 1963 and 1984, showing the migration from VHF CCIR-A to UHF CCIR-I and the introduction of CTV.
As Generation 7b 1968 U6.

[dazzlevision]

There is a circuit diagram, with component values and a component layout diagram for the G8 UHF tuner in the G8 chassis workshop manual. Section D, pages 13 and 14.

[slidertogrid]

When I had the shop we had a tuner in a box powered by some 9v batteries in series with a pot to tune it. Easy to make with a spare varicap tuner. Then if we suspected a tuner was low gain or a problem with the set's agc it was a simple job to connect the 'tuner tester' to the IF input and see if the fault remained or not. I think the idea came from an article in 'Television' magazine. If you can get hold of a spare varicap tuner of any type it would be easy to make one to eliminate (or not) the tuner in the G8. I cannot remember having any gain faults with the G8 beyond a faulty tuner but I think they have a IF gain module? so you may have a problem there especially if it used lockfit transistors which some people have reported problems with.
A lovely set! what a find in that condition!

Rich.

[matspar]

Thanks everyone for your input and advice. Always appreciated and I have plenty of things to explore now. I have a G8 factory manual on its way along with a spare signals board so hopefully I will get a result in the near future.
This G8 is a proper minter. God knows where its been hidden all its life but it is certainly a low hours set and is clean as a whistle. I purchased it from an auction house in Weymouth who told me it came from a house clearance in the local area. I suspect it was tucked away somewhere many a year ago.

[Mr Hoover]

Originally Posted by slidertogrid

When I had the shop we had a tuner in a box powered by some 9v batteries in series with a pot to tune it. Easy to make with a spare varicap tuner. Then if we suspected a tuner was low gain or a problem with the set's agc it was a simple job to connect the 'tuner tester' to the IF input and see if the fault remained or not. I think the idea came from an article in 'Television' magazine. If you can get hold of a spare varicap tuner of any type it would be easy to make one to eliminate (or not) the tuner

That's a very nice little test jig solution and would certainly have identified the problem in this case.
Yes, the Philips IF gain/selectivity etc module lockfit transistors may well be giving problems now.