How to tune a Philips G20T322 - UK Vintage Radio Repair and Restoration Discussion Forum

Duke_Nukem · 10th Dec 2005, 7:06 pm

OK, embaress me, just how on earth do you tune the G20T322 ? It's obviously varicap tuned so I assume there are some pots inside the black cover. But how to get in ?

Also, anyone know what year it dates from ? A label suggests 1972 but I'm sure it must be later than this ?

TTFN,
Jon

PS Oh yeah, and anyone has a spare control knob - looks like one that must have been used on lots of 70's tat radios (Fidelity springs to mind).

Nickthedentist · 10th Dec 2005, 7:28 pm

Does the 6-pressbutton assembly hinge forwards and outward, revealing edgewise multiturn pots

Nick

Hybrid tellies · 11th Dec 2005, 12:55 am

Hi Jon. did you see my email I sent you earliar today from work. As far as I can remember the tuning is as Nick suggested. I think Philips used the same type of tuning head as the G8/G9 colour sets.
As far as the age goes I would put it to the mid 1970's possibly as early as 1974. The 320 chassis replaced the Hybrid 300 chassis and was actually more reliable and gave a very good account of it self.

Duke_Nukem · 11th Dec 2005, 11:01 am

Quote:

Originally Posted by Nickthedentist

Does the 6-pressbutton assembly hinge forwards and outward, revealing edgewise multiturn pots

Not as far as I can tell. I can wobble the black plastic area maybe 1/2mm side to side, suggesting it is supposed to come out some how, but short of extreme violence I cant see any way of it coming off.

Quote:

Originally Posted by Hybrid tellies

Hi Jon. did you see my email I sent you earliar today from work.

Yep, I downloaded it just after posting the original message.

Quote:

Originally Posted by Hybrid tellies

As far as I can remember the tuning is as Nick suggested.

Nope, I'm still none the wiser :-( The black plastic surround is shaped so that you can't really grip it.

Being Philips, and given that the EHT is right next to this panel, I did wonder if they placed some sort of release mechanism at the back, but if they did then it is *very* well hidden.

TTFN,
Jon

roger_a · 11th Dec 2005, 11:17 am

Jon,

I'm sure the others are correct re the tuning method. Pictures on the 'net show the TV with very similar 6way switch unit as the G8 colour set.

The complete switch assembly will be pivoted at the bottom of each side. If you grab between the top left and the top right buttons, pull the ssembly down so that the top edge is horizontal (facing you), you should see the tuning wheels now facing up.

Also, there may be a small plunger switch which defeats the AFC. This would need to be pressed when you adjust the tuning for each station in turn.(On reflection,I think this works the other way around. The AFC is defeated automatically when the drawer is opened)

Good luck.

Roger

Nickthedentist · 11th Dec 2005, 11:23 am

It's a long, long time since I've fiddled with one of these, probably at a friend's house when I was about 5 or 6

I'm pretty sure that the pushbuttons hinged outwards and all you had to do this was pull at the top BUT have you tried pushing it in case it's got one of those latches (like the later G11's tuning drawer)?

Nick

Nickthedentist · 11th Dec 2005, 11:29 am

BTW, my R&TVS index lists the G20T325 as appearing in the 1973/4 volume, which seems to agree with what Simon thought

Mike Phelan · 11th Dec 2005, 12:01 pm

IIRC, Nick is correct - I assume it is the one with sloping buttons like the later colour G8 chassis.There is no locking mech - the assembly just pops out and down. Possibly someone has welded it to the base with some sort of switch cleaner solvent?

They were quite unreliable when a few years old.

gdTV · 11th Dec 2005, 5:33 pm

These may help......

Duke_Nukem · 12th Dec 2005, 1:55 pm

Thanks for all the suggestions.

Now convinced it really should open at the front, I ended up sliding a plastic ruler into the gap and started to lever it at the top. One minute, two chips out of the ruler and three 10p’s in the swear box later and it finally opened. Phew ! I would have hated to damage the set itself hence the caution.

I think the pots might be noisy as on some of the switch positions the tuning seems to bounce all over the place :-( But the top right one seems stable, at least long enough to take a piccy – I’ll have to try again later to confirm whether or not the height really is reduced or whether it is just the stations broadcasting at near 405-lines again .

Oh, and I’ve found a supplement for the provisional manual. It is dated September 1972.

Thanks for all the help.

TTFN,
Jon

PS : Don’t suppose anyone’s got one of the original chrome stand for the set ? No? Thought not.

brunel · 12th Dec 2005, 7:48 pm

You can clean the pots, if not badly worn.

Also, if there is an AFC switch, clean/scrape the copper where the wire part makes contact otherwise the AFC does not disengage.

I have a new one of these BUT it is for the G8 colour, if required.

Regards

Brunel

Welsh Anorak · 16th Dec 2005, 2:40 pm

Hi!
The pots are quite reliable but the switch isn't - this should be the rotary unit as opposed to the G8 sloping version. If you ease the casing apart after springing the plastic clips, the unit can be dismantled - but careful you don't lose the AFC button. Clean the PCB copper with Brasso then re-tension the Y-shaped phospor-bronze contacts. Lubricate with a little silicon grease and it'll work like new! Well, for a while, anyway....

10th Dec 2005, 7:06 pm	#1
Duke_Nukem Octode Join Date: Jan 2003 Location: Birmingham, West Midlands, UK. Posts: 1,268	How to tune a Philips G20T322 OK, embaress me, just how on earth do you tune the G20T322 ? It's obviously varicap tuned so I assume there are some pots inside the black cover. But how to get in ? Also, anyone know what year it dates from ? A label suggests 1972 but I'm sure it must be later than this ? TTFN, Jon PS Oh yeah, and anyone has a spare control knob - looks like one that must have been used on lots of 70's tat radios (Fidelity springs to mind).

10th Dec 2005, 7:28 pm	#2
Nickthedentist Dekatron Join Date: Jan 2005 Location: Oxford, UK. Posts: 17,844	Re: How to tune a Philips G20T322 Does the 6-pressbutton assembly hinge forwards and outward, revealing edgewise multiturn pots Nick

11th Dec 2005, 12:55 am	#3
Hybrid tellies Nonode Join Date: Jan 2004 Location: 1966-1976 Coverack in Cornwall and Helston Cornwall. 1976-present Bristol/Bath area. Posts: 2,965	Re: How to tune a Philips G20T322 Hi Jon. did you see my email I sent you earliar today from work. As far as I can remember the tuning is as Nick suggested. I think Philips used the same type of tuning head as the G8/G9 colour sets. As far as the age goes I would put it to the mid 1970's possibly as early as 1974. The 320 chassis replaced the Hybrid 300 chassis and was actually more reliable and gave a very good account of it self. __________________ Simon BVWS member

11th Dec 2005, 11:17 am	#5
roger_a Retired Dormant Member Join Date: Sep 2003 Location: Croydon, London, UK. Posts: 40	Re: How to tune a Philips G20T322 Jon, I'm sure the others are correct re the tuning method. Pictures on the 'net show the TV with very similar 6way switch unit as the G8 colour set. The complete switch assembly will be pivoted at the bottom of each side. If you grab between the top left and the top right buttons, pull the ssembly down so that the top edge is horizontal (facing you), you should see the tuning wheels now facing up. Also, there may be a small plunger switch which defeats the AFC. This would need to be pressed when you adjust the tuning for each station in turn.(On reflection,I think this works the other way around. The AFC is defeated automatically when the drawer is opened) Good luck. Roger Last edited by roger_a; 11th Dec 2005 at 11:37 am.

11th Dec 2005, 11:23 am	#6
Nickthedentist Dekatron Join Date: Jan 2005 Location: Oxford, UK. Posts: 17,844	Re: How to tune a Philips G20T322 It's a long, long time since I've fiddled with one of these, probably at a friend's house when I was about 5 or 6 I'm pretty sure that the pushbuttons hinged outwards and all you had to do this was pull at the top BUT have you tried pushing it in case it's got one of those latches (like the later G11's tuning drawer)? Nick

11th Dec 2005, 11:29 am	#7
Nickthedentist Dekatron Join Date: Jan 2005 Location: Oxford, UK. Posts: 17,844	Re: How to tune a Philips G20T322 BTW, my R&TVS index lists the G20T325 as appearing in the 1973/4 volume, which seems to agree with what Simon thought

11th Dec 2005, 12:01 pm	#8
Mike Phelan Dekatron Join Date: Nov 2003 Location: Near Leeds, West Yorkshire, UK Posts: 4,609	Re: How to tune a Philips G20T322 IIRC, Nick is correct - I assume it is the one with sloping buttons like the later colour G8 chassis.There is no locking mech - the assembly just pops out and down. Possibly someone has welded it to the base with some sort of switch cleaner solvent? They were quite unreliable when a few years old. __________________ Mike.

11th Dec 2005, 5:33 pm	#9
gdTV Retired Dormant Member Join Date: Nov 2005 Posts: 40	Re: How to tune a Philips G20T322 These may help...... Attached Thumbnails

12th Dec 2005, 1:55 pm	#10
Duke_Nukem Octode Join Date: Jan 2003 Location: Birmingham, West Midlands, UK. Posts: 1,268	Re: How to tune a Philips G20T322 Thanks for all the suggestions. Now convinced it really should open at the front, I ended up sliding a plastic ruler into the gap and started to lever it at the top. One minute, two chips out of the ruler and three 10p’s in the swear box later and it finally opened. Phew ! I would have hated to damage the set itself hence the caution. I think the pots might be noisy as on some of the switch positions the tuning seems to bounce all over the place :-( But the top right one seems stable, at least long enough to take a piccy – I’ll have to try again later to confirm whether or not the height really is reduced or whether it is just the stations broadcasting at near 405-lines again . Oh, and I’ve found a supplement for the provisional manual. It is dated September 1972. Thanks for all the help. TTFN, Jon PS : Don’t suppose anyone’s got one of the original chrome stand for the set ? No? Thought not. Attached Thumbnails

12th Dec 2005, 7:48 pm	#11
brunel Heptode Join Date: Sep 2005 Location: LEEDS.......North of the River Aire. Posts: 872	Re: How to tune a Philips G20T322 You can clean the pots, if not badly worn. Also, if there is an AFC switch, clean/scrape the copper where the wire part makes contact otherwise the AFC does not disengage. I have a new one of these BUT it is for the G8 colour, if required. Regards Brunel

16th Dec 2005, 2:40 pm	#12
Welsh Anorak Dekatron Join Date: Apr 2005 Location: North Wales, UK. Posts: 6,918	Re: How to tune a Philips G20T322 Hi! The pots are quite reliable but the switch isn't - this should be the rotary unit as opposed to the G8 sloping version. If you ease the casing apart after springing the plastic clips, the unit can be dismantled - but careful you don't lose the AFC button. Clean the PCB copper with Brasso then re-tension the Y-shaped phospor-bronze contacts. Lubricate with a little silicon grease and it'll work like new! Well, for a while, anyway....