11th Jan 2021, 1:53 pm | #141 |
Dekatron
Join Date: Apr 2011
Location: Cornwall, UK.
Posts: 13,454
|
Re: Philips G8 G22K522
Might also be worth checking the line discriminator balance control if not already done so as that will affect the voltage at the reactance transistor.
Lawrence. |
11th Jan 2021, 9:25 pm | #142 | |||||
Octode
Join Date: Jun 2018
Location: Essex, UK.
Posts: 1,307
|
Re: Philips G8 G22K522
Quote:
Quote:
Quote:
Quote:
I'd do checks tracing backwards from the fault but I'd not be sure at which components to be looking at. Quote:
Thanks '77 |
|||||
11th Jan 2021, 10:07 pm | #143 | |
Dekatron
Join Date: Apr 2011
Location: Cornwall, UK.
Posts: 13,454
|
Re: Philips G8 G22K522
Quote:
There should be a procedure in the manual for setting the line frequency, if you follow that it should give an idea as to whether it's the oscillator or the voltage that controls the reactance stage. Lawrence. |
|
12th Jan 2021, 1:12 pm | #144 |
Dekatron
Join Date: Apr 2005
Location: North Wales, UK.
Posts: 6,927
|
Re: Philips G8 G22K522
Those voltages look almost exactly right - you only need to go to one decimal place at most. Just check the adjustment slug hasn't fallen out of the coil - that frequency is so far out it has to be either that or a tuning component. There was no need for these oscillators to be crystal controlled, just to free run at approximately line frequency. Yours is galloping!
I'll get the manual out tonight and copy you the setting up procedure. |
12th Jan 2021, 8:14 pm | #145 | ||
Octode
Join Date: Jun 2018
Location: Essex, UK.
Posts: 1,307
|
Re: Philips G8 G22K522
Quote:
Quote:
Thanks for help, much appreciated '77 |
||
13th Jan 2021, 11:11 am | #146 |
Dekatron
Join Date: Apr 2005
Location: North Wales, UK.
Posts: 6,927
|
Re: Philips G8 G22K522
Here's what the manual says:-
Tune the receiver to a transmission and adjust the controls for a normal picture. Connect a voltmeter between TP9 and chassis and adjust R2177 for a reading of 6.4 volts. Reconnect the meter to TP8 and adjust L4501 for a reading of 6.9 volts. The two test points and R2177 are at the rear of the IF panel by the audio output transistor T225. You'll notice a 10uF capacitor C2170 nearby. Although it's a good quality component, it's possible this is faulty. |
21st Jan 2021, 3:50 pm | #147 |
Octode
Join Date: Jun 2018
Location: Essex, UK.
Posts: 1,307
|
Re: Philips G8 G22K522
Sorry for the late reply, just haven't had to chance really to do the set.
I've just done the adjustments, TP9 and R2177 was reading around 7.2 volts at first and is now at 6.4. TP8 and L4501 were at something stupid like 2 volts, and the coil was almost hard over to the anticlockwise. It's now almost hard over clockwise at 6.6V but we've a MUCH better picture, and the line-whistle isn't making my ears bleed anymore. The picture isn't stable with this, as it still scrolls left to right, but it's not slanted like it used to be. As you can see in the photo too, there's also a greeny-yellow/purpley-blue variation that overlays the main image and flies from right to left, and of course, no colour, but one step at a time. I'm starting to think this set's been the victim of a twiddler. Thanks all for the help, I really appreciate it '77 |
21st Jan 2021, 7:17 pm | #148 |
Octode
Join Date: Jun 2018
Location: Essex, UK.
Posts: 1,307
|
Re: Philips G8 G22K522
Weird discovery, I turned the set on again to see how it'd perform from cold, and there was loss of sync again, adjusting L4501 sort of brought it back to how it was before, with the scrolling, but I noticed if I take my coil adjusting tool out, it loses sync again, but there's not the 4 pictures this time so it's still somewhat of an improvement
Edit: My fault, I realised it's a metal tool, using a plastic one sorted this out. It still scrolls side to side but much slower. '77 Last edited by 19Seventy7; 21st Jan 2021 at 7:29 pm. |
22nd Jan 2021, 12:01 pm | #149 |
Dekatron
Join Date: Apr 2005
Location: North Wales, UK.
Posts: 6,927
|
Re: Philips G8 G22K522
You're losing sync, which does point to the Taa IC or an associated component.
I'm a bit concerned about excessive width and height - cleck the +205v rail. If that's OK you'll need to balance the BU205s. The lack of colour is possibly just the reference oscillator off lock as I think you can see unlocked colour in the display. |
23rd Jan 2021, 3:41 pm | #150 |
Octode
Join Date: Jun 2018
Location: Essex, UK.
Posts: 1,307
|
Re: Philips G8 G22K522
I’m hoping it’s not the IC... I’ll check the other components later on when I’m home, along with the 205V rail. I think it’s running at around 200V, but I’ll check again. If that’s okay, how do I balance the BU205s? Is that the coil next to the green tuning caps which I think was mentioned earlier on in this thread?
I’m not entirely sure if it’d be the cause, or part of it, the colour control seems to just spin, so I’m not sure what condition the pot itself is in, there’s no difference if the control is at the maximum or minimum. Thanks ‘77 |
23rd Jan 2021, 6:58 pm | #151 |
Hexode
Join Date: Nov 2006
Location: Colchester, Essex, UK.
Posts: 397
|
Re: Philips G8 G22K522
Been working on a G8 this afternoon with no line sync. It turned out to be c4520 on the timebase panel. It decouples the emitter of T500. It is 16mfd.
Dave |
23rd Jan 2021, 9:25 pm | #152 |
Octode
Join Date: Jun 2018
Location: Essex, UK.
Posts: 1,307
|
Re: Philips G8 G22K522
Thanks for the heads up, I’ll give it a check in a bit and let you know.
Thanks ‘77 |
24th Jan 2021, 1:47 am | #153 | ||
Octode
Join Date: Jun 2018
Location: Essex, UK.
Posts: 1,307
|
Re: Philips G8 G22K522
Had a check, C4520 in mine was a 33uF cap, I checked the capacitor and it seemed way out of value, so I've ordered some. Hopefully this cures the sync fault, we'll soon find out.
Quote:
Quote:
Thanks for the help '77 |
||
24th Jan 2021, 6:03 pm | #154 |
Dekatron
Join Date: Oct 2003
Location: Croydon, Surrey, UK.
Posts: 7,580
|
Re: Philips G8 G22K522
When I was at Philips, we used to set the HT to 200V....not official but we got fed up with changing line output transistors and transformers.
__________________
There are lots of brilliant keyboard players and then there is Rick Wakeman..... |
24th Jan 2021, 6:31 pm | #155 |
Heptode
Join Date: Dec 2004
Location: Newport, Gwent, UK.
Posts: 962
|
Re: Philips G8 G22K522
I've set several of my A823's to around 190-195v whether it makes a difference or not because on occasion the pot has become intermittent and it has shot up to 220-ish volts.
Cheers Neil. |
24th Jan 2021, 10:46 pm | #156 | ||
Octode
Join Date: Jun 2018
Location: Essex, UK.
Posts: 1,307
|
Re: Philips G8 G22K522
Quote:
Quote:
Thanks ‘77 |
||
24th Jan 2021, 10:55 pm | #157 |
Dekatron
Join Date: Oct 2003
Location: Croydon, Surrey, UK.
Posts: 7,580
|
Re: Philips G8 G22K522
If the HT goes too high, the power supply tends to 'hunt' giving you a pulsing picture. If you check the setup details there is a 'course' and 'fine' adjustment. I really don't remember the sequence now but I seem to recall that you set the HT pot to 210V then adjust the other so that the picture hunts and then back off the HT pot to 205V....something like that anyway.
__________________
There are lots of brilliant keyboard players and then there is Rick Wakeman..... |
25th Jan 2021, 12:27 am | #158 |
Dekatron
Join Date: May 2010
Location: Greater Manchester, UK.
Posts: 18,725
|
Re: Philips G8 G22K522
I don't recall a fine adjustment, just a set HT and an overvoltage protection pot.
The pulsating was the overvoltage protection kicking in. To set the latter empirically, we would set the HT correctly on a meter, then set the overvoltage pot until the picture pulsated, then back it off a bit.
__________________
-- Graham. G3ZVT |
25th Jan 2021, 11:20 am | #159 |
Dekatron
Join Date: Apr 2005
Location: North Wales, UK.
Posts: 6,927
|
Re: Philips G8 G22K522
To answer your question, the balance coil is indeed on the small sub-panel. However the core will be stuck, so it needs to be soaked to free it off. Once you get the sync sorted out then you can adjust this - it's fine for the moment.
As said, around 200v is fine. It's quite well stabilised, but not up to later standards so as long as it hovers around 200v then it's OK. Graham's method of setting up the overrvolts is the one we all used. |
25th Jan 2021, 12:34 pm | #160 |
Dekatron
Join Date: Aug 2013
Location: Wigan, Greater Manchester, UK.
Posts: 9,433
|
Re: Philips G8 G22K522
There is a page on sorting out the stuck core, the information was originally in Television magazine from 1985.
https://www.radios-tv.co.uk/vintage-...tor-balancing/
__________________
Frank |