1971 Philips G6.

[FERNSEH]

On Saturday I accompanied Gary (system A in this Forum) to Mikey's place in Solihull.
The objective of the 220 mile trip was to collect Gary's latest acquisition, a very rare 26" Philips G6.
Without delay we set about preparing the set for it's restoration. First, connect the set up to the variac and slowly introduce the set to mains power. Before long we were greeted with a thin white line across the screen.
In the G6 there is a 100ohm resistor inserted between the anode of the PL508 frame output valve and the primary of the transformer and it was getting very hot.
Well it seems that in the event of the frame oscillator failure the output stage draws excess current. The cause of the frame oscillator fault turned out to be the 1.5megohm anode load resistor of the ECC81. The G6 is unusual in having a cathode follower buffer stage between the oscillator and the grid of the output valve, the CF uses one half of a PCC85. The other triode section is used a frame flyback pulse shaper.
So that's the frame timebase working, although there is only just sufficient height. Replacing a 680Kohm 1watt resistor on the line timebase PCB resulted in having plenty reserve height adjustment.
It must be mentioned during the early stages of the restoration the PY500A boost diode took to glowing like a light bulb. This turned out to be a 0.33mfd decoupling capacitor in the heater chain.
Connecting the set to a source of signals gave us a picture of sorts. Not very good with what looked like maladjusted bandpass rejector coils and there is a lot of those in the IF amplifier.
We had fears that the IFs had been twiddled and it looked like a full realignment procedure would be required and that will not be easy because almost all the coil cores are stuck fast. No adjustment possible.
However, over time the picture did improve until the idea of realignment was abandoned. Thank goodness for that!
And the set even displays colour, but that condition known in G6 sets was noticed where the colour control operates in a strange manner.
More about the G6 restoration to follow.

DFWB.

[Welsh Anorak]

Very nice! I've never seen the cabinet version of this - I remember the G22K511, of course, plus the G25K512 and the rare G26K513, though all these were without doors.
The dual standard version had a famous Philuips 'drop off' resistor in the PL508's anode circuit, and many a happy hour could be spent rummaging around the customer's carpet...

[FERNSEH]

The attachments show the excellent pictures this set is capable of showing.

DFWB.

[Welsh Anorak]

On paper, the G6 should never have worked properly and been spectacularly unreliable. It proved to be neither, and indeed the last of the dual based hybrids (used by a customer) I retired was a '511 G6.

[FERNSEH]

According to the Mastercare record card the set had given reliable service to it's owner up to 1978 but later in the life of the set a few call outs were required to correct faults. Four service visits in 1978 and one per year from 1979 to 1981.
In those times one service each year was considered perfectly satisfactory.
In fact if one analyses the nature of the service calls even those in 1978 there was nothing out of the ordinary.

DFWB.

[Richard_FM]

I assume this is one of the later single standard G6s.

[AJSmith625]

Hello David, That was a blast from the past seeing a Mastercare service record card again. I wander which part of the country the set originated from. I don't recognise any names there. Excellent picture by the way.

Alan.

[FERNSEH]

Hi Alan,
As far as I now the set originated in the Midands, Gary bought the set from a collector in Kidderminster.
Hi Richard,
The set is a 625 line only receiver. The 26" square corners CRT was introduced late 1970, a year after all three TV services in the UK went colour. According to the Radiomuseum the developer of the A66-120X was Telefunken.
https://www.radiomuseum.org/tubes/tube_a66-120x.html
A 22" dual standard G6 model was announced by Philips in 1968.

DFWB.

[FERNSEH]

Another off-screen picture.

DFWB.

[peter_scott]

Looks really good!

Peter

[Tazman1966]

Looks lovely David.

[Radio Wrangler]

The family of a schoolfriend had a G6 just like the one being brought back to life. Back in the day it was a very very impressive set. The convergance panel was terrifying!

David

[Maarten]

I don't think radiomuseum.org states the developer of this tube was Telefunken, though they might have been since they were one of the major manufacturers. Logically it could have been Telefunken or Philips (Mullard, Valvo, RTC), possibly SEL.

[FERNSEH]

Hi Maarten,
yes, your right the Radiomuseum simply states that TFK was a brand making and marketing the A66-120X.
Same goes for the A56-120X: https://www.radiomuseum.org/tubes/tube_a56-120x.html
I've always believed Mullard took on the development of the "square corners" A56-120X, but I could be wrong.

DFWB.

[Richard_FM]

Originally Posted by FERNSEH

Hi Alan,
Hi Richard,
The set is a 625 line only receiver. The 26" square corners CRT was introduced late 1970, a year after all three TV services in the UK went colour. According to the Radiomuseum the developer of the A66-120X was Telefunken.
https://www.radiomuseum.org/tubes/tube_a66-120x.html
A 22" dual standard G6 model was announced by Philips in 1968.

DFWB.

You are welcome, I did wonder because the G8 was launched not long after.

It looks like it's working great, keep up the good work.

[FERNSEH]

Hi Richard,
The first 22" Philips G8 model was launched in late 1970.

As mentioned in an earlier post we got lucky with the G6 because the IF panel seemed to fix itself. Over the course of time the pictures just got better and there was no need whatsoever to do any adjustments to the IF transformer cores.
The attachments show the frequencies the transformer cores must be adjusted to. The 41.1Mhz and 41.5Mhz traps L2783 and L2586 are described in the alignment instructions as "channel 1" rejectors. These along with the 33.5 and 33.7Mhz traps define the response curve limits.
Interestingly, the progenitor of the G6 is the Continental K6 which differs from the UK model in having an all valve IF amplifier, EF183 two EF184s and the pentode section of a PCF200.

http://www.technischmuseum.nl/devices/Philips%20K6/Philips%20K6.html

DFWB.

[unitaudio]

Our first colour telly was one of these but without the doors. I was a toddler when it appeared in 1972. Not seen one for over 40 years but I remember it well!

Regards,
Paul

[System A]

Hi, here's a real fun photo taken last weekend at Mikey's. Here we see David (FERNSEH) trying to retrieve Nipper's toy.

Regards, Gary.

[Hybrid tellies]

A few of our customers had these single standard G6's. Always a good picture but a bit of a nightmare to fix as we were not very familiar with the G6.

[Welsh Anorak]

I was always surprised that the most reliable panel (in theory) on the G6 was made pluggable on the single standard versions. Repair of the timebase panel could have been easier if that could have been removed too. I know of several people who actually replaced the decoder board with varying degrees of success, I have to say. I found repairing them was preferable!
Oddly the most common fault (besides the obvious ones) I had on the single standard G6s was a transformer in the demodulator can resulting in odd colours. Luckily scrap sets were plentiful in the late Seventies.
Of course hindsight is a great thing, but I wish I'd kept the G22K503 and the pre-production dual standard in a strange cabinet I had, but obviously they'd never be collectable would they?