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Old 27th Jun 2020, 11:24 pm   #81
19Seventy7
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Default Re: Philips G8 G22K522

Quick update:

Resoldered R516, the HT drops within seconds, so that's cleared that fault up, but my DMM is still reading near the 260V mark.

It might sound a bit odd, but I've noticed it reads at 260V more at night/evening, than it does during the day, so I'm wondering if temperature has affected the DMM, I know it can but I don't know if it's the case here.

I'll test again tomorrow and see.

Thanks
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Old 28th Jun 2020, 8:23 pm   #82
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Default Re: Philips G8 G22K522

Try a new battery in the meter.
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Old 28th Jun 2020, 10:57 pm   #83
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Default Re: Philips G8 G22K522

Don't know why I didn't think of that but it worked! Realised I'd been using cheap batteries in it, died VERY quickly.

To go along with with the smoke from the LOPT, we had some sparks from the mains dropper, but was nothing to worry about, just a loose connection. That's fixed.

Sorry if this is a stupid question but what should and what shouldn't work with Plug H unplugged? Just the transductor?

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Old 29th Jun 2020, 10:55 am   #84
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Default Re: Philips G8 G22K522

Yes - it's just the transductor. When all's finished you can reconnect it - it's just they had a habit of failing and it's one less thing for you to worry about. Slight pincushion distortion will be the least of your worries!
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Old 29th Jun 2020, 5:27 pm   #85
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Default Re: Philips G8 G22K522

Okay thank you, that's good to know.

I'm still on the search for the dry joint(s), still no EHT or sound. Hopefully when the joint's found i'll get a raster again.

Thanks for the help
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Old 4th Oct 2020, 9:59 pm   #86
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Default Re: Philips G8 G22K522

Hi all

It's alive!!!

After almost a year of on and off work, the G8 gives a picture (Of snow and lines) and sound!
All it needs now is the H hold and convergence done, which leads me to my next, and hopefully last, question

Where would someone find the horizontal hold control on the G8, I've given it a thorough looking over but can't find anything and don't want to twiddle anything that doesn't need it.

Thanks all for the help, it's really appreciated
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Old 4th Oct 2020, 10:28 pm   #87
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Default Re: Philips G8 G22K522

Looks like one of the old G8s in which case it might have a pair

of BU205 line output transistors (later ones had just a single BU208)

From memory if one BU205 dies, (depending on how it dies)the set will still work as yours does, but will have faults in the obvious areas ..just a thought.
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Old 4th Oct 2020, 10:31 pm   #88
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Default Re: Philips G8 G22K522

It's a '71 model so is early, very early. I'll check those transistors and see how they're doing

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Old 5th Oct 2020, 12:42 pm   #89
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Default Re: Philips G8 G22K522

I doubt the BUs are a problem here.
The big book says L501 (right at the front of the timebase panel by the plug) is the line frequency adjustment. I agree - why would it need adjusting? However very careful (plastic tool) adjustment might reveal loss of line sync, though might just get you a picture.
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Old 5th Oct 2020, 7:55 pm   #90
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Default Re: Philips G8 G22K522

Sorry for the late reply

Both the BUs looked to read alright, so I don't think it's them, but I don't suppose they're totally ruled out just yet.

I gave it adjustment with a carved down pen lid and actually got results they're not perfect but it's something

It still flies off to the side. I soon lost that image though after still adjusting, trying to get it to lock. I'm wondering if heat might be an issue too, causing drift on something as I could get a recognisable picture at first, then when the set had been up and running for a while, no dice

But some good news, the CRT is nice and bright on all 3 colours so has a good tube

Thanks
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Old 5th Oct 2020, 8:53 pm   #91
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Default Re: Philips G8 G22K522

Line sync looks like it's missing. Suggest checking around that area
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Old 5th Oct 2020, 10:04 pm   #92
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Default Re: Philips G8 G22K522

My thoughts too, I noticed some resistors getting really hot, hotter than others, so i'm curious if it's around those, or even those, considering they're right next to the line hold coil, so i'll check those out

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Old 6th Oct 2020, 4:18 pm   #93
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Default Re: Philips G8 G22K522

Don't ever recall a line sync fault on a G8. It wuld be very helpful if you could borrow a timebase board. Unfortunately I don't have one but someone might. Meanwhile I'd check the edge plugs and sockets - it's not unknown for one of the pins to raise up out of the chassis monting plug.
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Old 6th Oct 2020, 9:29 pm   #94
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Default Re: Philips G8 G22K522

Indeed it would be helpful, it's a shame really as I'm sure there were some G8 panels going fairly cheaply on that auction site.

As for the edge plugs, I unplugged the board and re-seated it, alas still no luck. Though I did notice a handful of dry joints which I'm going to sort out tomorrow. Oh and I read in the 1978 June issue of television that if the VCR compatible mod has been done, sometimes it can affect line sync and so needs to be reverted back to original, which I'll also look out for

Thanks
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Old 7th Oct 2020, 3:04 pm   #95
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Default Re: Philips G8 G22K522

Quote:
Originally Posted by Sideband View Post
Line sync looks like it's missing. Suggest checking around that area
I haven't got a G8 any more and haven't even got the manual nearby to check, but isn't there a single (yellow, I think) fly lead from the signals panel to the timebase board feeding in the sync signal? Is it definitely connected?
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Old 7th Oct 2020, 3:36 pm   #96
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Default Re: Philips G8 G22K522

At this point we need to know if you have a combined or twin signals panel. Although it's an early G8, it's possible a combined board has been fitted. Easy to tell - the bottom of the chassis either has three boards or one big and one small one.
The line flywheel discriminator is in the TAA700 (early panel). Frame sync comes out of pin 15 via Tas's yellow wire and line control from pin 2. This goes via connector A11 to F11 on the timebase panel, arriving at T500's base where you should find around 7v. There's a 4uF decoupler here, and don't forget T500 is a lokfit so plenty to have a look at here.
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Old 8th Oct 2020, 2:52 am   #97
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Default Re: Philips G8 G22K522

Quote:
isn't there a single (yellow, I think) fly lead from the signals panel to the timebase board feeding in the sync signal? Is it definitely connected?
There is, it was connected, but as I removed the timebase panel and then reseated it I made sure it was reconnected, though it could be disconnected on the signals board as I did have to reseat the tuner too, not yet checked that out as I didn't know the yellow lead dealt with sync

Quote:
we need to know if you have a combined or twin signals panel. Easy to tell - the bottom of the chassis either has three boards or one big and one small one.
It's got the three separate boards. I'll have a poke about with the multimeter tomorrow and let you know what's going on. I think we're almost there with it

Thanks for the help
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Old 8th Oct 2020, 9:52 am   #98
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Default Re: Philips G8 G22K522

As a matter of interest, does it have the TBS530 on the decoder board? Some very early G8s had a sub-panel with lots of transistors instead as the chip's supply was delayed. I've never seen one as they were notorious for grey scale drift and were routinely changed for the slightly later board. Not relevant to your Tv, of course, just curious.
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Old 8th Oct 2020, 3:42 pm   #99
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Default Re: Philips G8 G22K522

Hi,

Sorry to disappoint but unfortunately (or fortunately, depending on which way you look at it) It's not got a TBS530, but a TBA530, though the board has got what I'd imagine to be mounting slots for the sub panel in the back left corner (Looking from the back of the set)

As for the fault, there's 7 volts at the base of T500 so all's good there, but it seems as if the 4uF decoupler is at fault here, testing it on a multimeter with capacitance setting it goes up to about 9.8XX and then reads OC, on a second multimeter it goes almost instantly to OC, no time to see what that one reads. Sods law being I can't find a suitable 4uF cap online, I'll have to go as close as I can and make one up out of 2 2.2uFs, unless anyone has a 4uF rated at 64v or higher they'd be willing to sell?

Thanks
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Old 9th Oct 2020, 10:27 am   #100
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Default Re: Philips G8 G22K522

Firstly, Mr Sausage Fingers typed TBS instaed of TBA - there's no such thing as a TBS530! I'd be very surprised if any surviving G8s had the odd sub-panel - I've never seen one and I've serviced countless G8s.
Your 4uF actually might be OK. What happens is meter 1 charges up the capacitor, ramps up then reads O/C. Meter 2 is presented with a charged capacitor and reads it as O/C, so don't be too disappointed if it doesn't work. Two 2.2uFs in parallel will be absolutely fine - it's just a decoupler. It would be nice, of course, to have a 'scope to look at what's coming out of the TAA700, but we can get by without. Can you confirm that's the chip you have on the IF panel?
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