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Old 18th Jan 2020, 10:17 am   #61
thermionic
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Default Re: Philips G8 G22K522

That’s a promising start!

Please DO ensure you measure and check the HT voltage at the 800mA fuse as mentioned previously by many others.

As you have moved both the Set HT, and Overvolts presets, it’s very important to check this.

Too high a HT will stress this old girl, and you don’t want to cause any damage. With the set disconnected from the mains, connect your red meter lead to the HT fuse, your black meter lead to chassis. Set your meter to DC Volts on a range of at least 250 Volts or higher.

Switch the set on, and check the voltage. Adjust the Set HT preset for 200 Volts.


Good luck!


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Old 18th Jan 2020, 3:08 pm   #62
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Default Re: Philips G8 G22K522

Hi,

I’ll get to checking the set later on, or tomorrow at latest. The set wont be powered on again until it’s been adjusted.

Thanks for your help
‘77
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Old 19th Jan 2020, 12:05 am   #63
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Default Re: Philips G8 G22K522

Quote:
Originally Posted by 19Seventy7 View Post
Are there two different controls for the guns on the convergence panel? There’s three at the bottom, which are just simple push button, which I figured turns the guns off or on, no different brightnesses. I haven’t looked around in there much, apart from the on/off buttons.
Apologies for misleading you, I thought the A1 pots were there as will as the push-buttons. It would be good if you posted a picture of those hidden convergence controls to remind me what they looked like.
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Old 19th Jan 2020, 1:43 am   #64
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Default Re: Philips G8 G22K522

No problem at all, for all I knew, you were right. I've attached a photo below.

The set was reading at 297 volts in it's original(ish) position! It's now at 200 volts.

Although now I cant seem to get EHT. I've not got a line whistle, and even giving the set a smack doesn't bring it back, like it used to. Dry/cracked joint(s) will be hunted down soon.

Thanks for your help, I really appreciate it
'77
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Old 19th Jan 2020, 3:11 pm   #65
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Default Re: Philips G8 G22K522

Are you sure your meter is OK, Is it set for DC volts?
I am surprised you can adjust the PSU to be as high as 297v and even more surprised that the output transistors survived.

Thanks for that the picture
Anyway I wasn't mistaken after all. Feel free to adjust the three Grey scale setting pots, they are in fact the A1 (first anode) controls under a different name.
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Old 19th Jan 2020, 4:04 pm   #66
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Default Re: Philips G8 G22K522

I'd be surprised if you could get anywhere near that H.T. What multimeter are you using? Perhaps post a picture of your meter..
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Old 19th Jan 2020, 10:48 pm   #67
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Default Re: Philips G8 G22K522

I wouldn't be surprised if it is a bit faulty, it was very cheap, around £10 online.

I set it to 600V (V-), because it goes from 200 - 600.

I thought that perhaps a resistor or something had failed, letting the PSU get to that high voltage?

Thanks for letting me know about the A1 controls, i'd have just thought they were still part of the convergence controls. I'll give those a twiddle and see if i get anything else on screen.

Picture of meter:
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Old 19th Jan 2020, 11:02 pm   #68
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Default Re: Philips G8 G22K522

600 to the left of OFF or 600 to the right of OFF?

V~ is to measure AC, you want to measure DC.

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Old 19th Jan 2020, 11:08 pm   #69
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Default Re: Philips G8 G22K522

Hi sorry, should've cleared that up, it was to the left of OFF.

Thanks
'77
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Old 20th Jan 2020, 12:00 am   #70
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Default Re: Philips G8 G22K522

I'd try to get a better meter if I was you, loads of reviews on YouTube. An auto ranging multimeter would be easier. You could probably pick up a better meter for not much more money. A multimeter is the most important tool in this game.

Just my thoughts..
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Old 20th Jan 2020, 2:08 am   #71
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Default Re: Philips G8 G22K522

I have been planning on getting a better one soon, but I've never had the money.

I've just had a look online and found a couple, I'll order one soon. I'll remeasure the voltage and go from there.

In the mean time, i'll hunt down any dry/cracked joints and see how it goes.

Thanks
'77
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Old 16th Mar 2020, 7:58 pm   #72
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Default Re: Philips G8 G22K522

The work resumes.

New multimeter arrived today, adjusted the set back to 200V (Old multimeter was off by 33 volts)

EHT builds up and speaker crackles to life. Nothing on screen however, but I get the typical static sound. Turning the red gun off gives me a green, slightly pin cushioned, raster.

I fed a signal into the TV, but the TV didn't pick it up, cycled through UHF 21-69 on my modulator on all 6 channels, but nothing.

The droppers on the PSU and the linescan panel are also running very hot, too hot to touch for even a second or two. Is this normal?

Not sure what to go about now. I really need to get my hands on a service manual.

Any suggestions as to what to? I haven't got a service manual so not sure what's needed.

Thanks
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Old 16th Mar 2020, 9:28 pm   #73
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Default Re: Philips G8 G22K522

When working on any radio or TV it really is important to start with a schematic especially when repairing to component level.

The first production and later G8 schematic, photographs other member's threads and helpful information can be found by searching "Philips G8" on this website.

Hope this helps

Chris
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Old 16th Mar 2020, 9:30 pm   #74
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Default Re: Philips G8 G22K522

Just realised I forgot to mention:

There's a dark bar along the top of the screen (Doesn't seem to be burnt phosphors) Looks as if there's alternating rows of phosphors being hit, not entirely sure, I found a stock fault "Every second line of colour missing (Bistable stopped) IC7001 (TAA630) but i'm not sure if it'd be this as it's only a portion, and it's not like colour is missing, just that they're not being hit.

I've managed to get red, although very dim and only when the contrast is right down, but it doesn't stay for long.

I found another stock fault that says "Too much or no red: to check for T7332 (BD115), T7582 (BC158), Check for dry joints at T7332" so that most likely answers what's wrong with red, although I got it being driven from green on the chrominance panel.

Edit: Post crossed with Simpsons. I'll start gathering any helpful information from this forum and filing it all together. Thanks

Some photos, sorry for the awkward angles. Best I could get.
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Old 17th Mar 2020, 2:57 pm   #75
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Default Re: Philips G8 G22K522

Some bad news.

Continued on the set, checking those points mentioned in the stock faults. Realised the tuner wasn't connected properly, so I resat the tuner and thought to turn the TV on to see if it made any difference.

Upon turning on the LOPT started smoking very badly, with a bright flash of orange light, which looked like flames, which has left a burnt section on the wires.

So until I can find a replacement LOPT, I guess anymore work is postponed. I'll put a ad in the Wanted section of this forum.

Thanks
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Old 25th Jun 2020, 10:47 pm   #76
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Default Re: Philips G8 G22K522

Back in the game!

New LOPT has been installed (Thanks to Davidbi), and (Hopefully) all dry joints resoldered.

I switched the set on again tonight, with the set HT at the lowest it can go. Few seconds pass and I can hear line whistle and no signal static from the speaker. All seems good there. Switch off the set again, give it a Testcard F signal, switch back on and watch the multimeter.

Bubble bursts there. The multimeter read 260 volts (I'm not sure what it read when I had EHT and sound) even with the set HT potentiometer at its lowest. No sound and no line whistle. Turn the set off, unplug it and feel components. "62" on the power supply board is very hot to the touch. Too hot to keep your finger on.

That's as far as I am at the moment with it. Could this potentially be causing the spike? I don't know it's value but there's a picture below.

Thanks
'77
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Old 26th Jun 2020, 1:21 am   #77
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Default Re: Philips G8 G22K522

62 is the degaussing pozistor and will run hot unless you unplug the degaussing coil.
I would strongly advise obtaining a spare eht tripler.
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Old 26th Jun 2020, 9:01 pm   #78
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Default Re: Philips G8 G22K522

Oh right okay. I’ll poke about elsewhere, i’ll look into another tripler. This one seems to be okay for now.

As for the 260V reading, I’m not sure what happened, but I’m now thinking it calibrated with some number being 0.

I retested it again today and it read at 137V, as it should do. I slowly raised it to 195V but no sound and EHT again, so I’ve missed some dry joints. I turned the set off and realised the HT voltage doesnt drop instantly (not that I expected it to, but it takes a good few minutes.) I think when I turned the set on for the second time last night, with a signal, the DMM recalibrated wrong.

Thanks
‘77
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Old 27th Jun 2020, 11:07 am   #79
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Default Re: Philips G8 G22K522

The fact that your HT drops very slowly suggests that the line stage isn't drawing current with chimes with your lack of EHT and so on. So you need to find that dry joint. Favourite place is the feed resistor to the line stage. This is R516, a 10k wirewound resistor in the middle right of the timebase panel by the transductor. This normally runs hot as it drops 200 to 18 volts - if cold you've found the problem.
While you're there, remove plug H behind the transductor if you haven't already. This can stay out while you're busy faultfiding as the transductor can burn out and you've had quite enough smoke from this set!
Dropper resistors do get very hot, and it comes as quite a surprise to people used to working on more modern equipment.
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Old 27th Jun 2020, 1:46 pm   #80
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Default Re: Philips G8 G22K522

I’ll get to doing those tonight. I’m not home for a little while but will get to doing it. I’ll definitely unplug H, One plume of smoke is enough for me! Found out about the droppers getting hot the hard way!

Thanks for pointing out R516.

I’ll report back later when I’ve checked it out.

Thanks again, appreciate the help.
‘77
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