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Vintage Television and Video Vintage television and video equipment, programmes, VCRs etc. |
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24th Sep 2021, 12:02 am | #241 | ||||
Octode
Join Date: Jun 2018
Location: Essex, UK.
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Re: Philips G8 G22K522
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I'll keep the picture jumping in mind too, should that come up. Quote:
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HOWEVER - The pitch of the line whistle didn't change like it did when the picture had no hold, so it's looking sort of promising! Quote:
I've been looking for one of those blue books for a while now, I've only seen one on ebay. One day! Thanks '77 |
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24th Sep 2021, 8:00 am | #242 |
Dekatron
Join Date: Oct 2003
Location: Croydon, Surrey, UK.
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Re: Philips G8 G22K522
You must look at what is on the circuit. I am quite sure that Philips have clearly marked the chip as a TBA550Q so that would give no doubt whatsoever as to the correct chip to fit. As to your other comment about the circuit not meaning much as you haven't much clue how to read it....I suggest you get some practice in! Hoping and poking at a complex circuit is not going to get you far, you won't learn much and it could be expensive in just changing parts for the sake of it.
Anyway you need to replace like-for-like and another word of warning...if you come across a chip with an A or B suffix (example TBA550AQ) and you have a TBA550BQ don't assume it will work! Very often there are subtle differences within the chip and possibly some component changes on the PCB so using the wrong suffix can be the difference between the set working or not working. Been there done that and got several T-shirts!
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24th Sep 2021, 10:51 am | #243 |
Dekatron
Join Date: Apr 2005
Location: North Wales, UK.
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Re: Philips G8 G22K522
Seconded. Thiis is particularly the case with Philips TVs. For example the line oscillator IC in the 320 mono had to be exactly correct or else it wouldn't work. Find the correct IC then let's see where we are.
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24th Sep 2021, 4:21 pm | #244 |
Dekatron
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Re: Philips G8 G22K522
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24th Sep 2021, 8:44 pm | #245 | |
Octode
Join Date: Jun 2018
Location: Essex, UK.
Posts: 1,306
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Re: Philips G8 G22K522
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I’m getting better with circuit diagram reading, I know the basics but thats about it, though I am very slowly learning. There’s not many places online (That I’ve found) which teaches you how to read more complex ones. Though I have to say as much of a hassle this set has been, it has taught me a lot I’ve got an IC in the post so shouldn’t take too long to get here. I’ll fit it and post results ASAP So i take it they’re somewhat interchangeable in some circuits, and not in others Thanks ‘77 |
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25th Sep 2021, 9:11 am | #246 |
Dekatron
Join Date: Apr 2005
Location: North Wales, UK.
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Re: Philips G8 G22K522
I think you need to know which BA version you have. Curiously, my book has most of the versions of the twin panel signals unit to BA06 which all appear to use a 700. However the spares list also has a 550 under a different part number! The combined panel used a 550 exclusively and there are some differences between this circuit and that using the 700.
Short answer - wait for the 550 then worry |
25th Sep 2021, 5:53 pm | #247 |
Octode
Join Date: Jun 2018
Location: Essex, UK.
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Re: Philips G8 G22K522
Sods law…
I have detailed photos of all boards except the one we need! Just out of curiosity I’ll take a look later. Shouldn’t take too long for the 550 to get here and get fitted and then I’ll report back Thanks ‘77 |
25th Sep 2021, 6:37 pm | #248 |
Nonode
Join Date: May 2007
Location: Redruth, Cornwall, UK.
Posts: 2,562
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Re: Philips G8 G22K522
Hi.
In part 2 of Mike Phelan's servicing article on the Philips G8, TELEVISION magazine, July 1978, he quotes: "Video IC Faults The two types of video i.c. TAA700 and TBA550Q differ only in the way the pins are bent - also the TAA700 has wider pins. So it's possible to interchange them. A faulty TAA700 can give no video at all, no sync, or what appears to be a black hum bar, with a buzz on sound, variable by the a.g.c. crossover control. The TBA 550Q can give any of these faults plus no field sync and a noisy picture due to faulty a.g.c. action." Regards, Symon |
25th Sep 2021, 8:24 pm | #249 |
Nonode
Join Date: Aug 2007
Location: Walsall Wood, Aldridge, Walsall, UK.
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Re: Philips G8 G22K522
Hi!
Still on the subject of G8 books, I believe the Original G8 Loose–Leaf Blue Binder didn't go up to the combined signals panel, that was covered by a thin floppy paper covered "550" manual in the dark blue cover with silver lettering! Oh yes, if you do get a Combined Signal Panel to try in your set, please don't forget to look at resistor R3212 (750 kΩ) connected from the brightness clamp pin of the '560CQ to the +205 V h.t. line, if this goes high in value or o/c., you get a raster that's black on the left and gradually shaded to white on the right, sometimes with hazy monochrome picture content on it, sometimes not, depending on how the '560CQ likes not having the d.c. clamp bleed current that should come down from the h.t. supply line! Chris Williams
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It's an enigma, that's what it is! This thing's not fixed because it doesn't want to be fixed! Last edited by Chris55000; 25th Sep 2021 at 8:34 pm. |
25th Sep 2021, 10:44 pm | #250 | |
Octode
Join Date: Jun 2018
Location: Essex, UK.
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Re: Philips G8 G22K522
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I'll keep in mind R3212 if i do get a combined panel to try. That'll 100% be my next step after trying this 550Q. I think I actually saw a post on VRAT about R3212 failing. Thanks all '77 |
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29th Sep 2021, 9:06 pm | #251 |
Octode
Join Date: Jun 2018
Location: Essex, UK.
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Re: Philips G8 G22K522
Hi all
Just an update, i've fitted a 550Q and have got an unlocked raster (Which will of course need adjustment) But thats only when I've got EHT, which is never very long. There's obviously a dry joint somewhere but I just cannot find it, I've reflowed the PSU and the Linescan panel both, and have gone over the other panels and any joints that looked questionable. I've always had this issue of a dry joint preventing the EHT from kicking up but never this bad and has always been solved with a quick smack - Not even a beating is working now. I just wanted to give an update to say that the 700 was at fault, but unsure yet as to whether the original 550Q was faulty too. Now on to reflow even more joints - again Thanks '77 |
29th Sep 2021, 9:24 pm | #252 |
Dekatron
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Re: Philips G8 G22K522
This is where you need a scope. You'd probably locate the area of the fault in a few minutes. We only had an hour and a half to find faults on these when in the Philips workshop. It rarely took that long except perhaps with a tube change. If it looked like being a nasty intermittent, we could fall back on the replacement panel solution. We didn't do that often as they were basically reserved for the field engineers who were always on a tight schedule.
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29th Sep 2021, 10:04 pm | #253 |
Octode
Join Date: Jun 2018
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Re: Philips G8 G22K522
I'd like to get a scope but i really don't have the money to get one and an isolation transformer, unfortunately. I'm going to go over any that still look poor and remove the solder completely, and give it fresh solder, hoping that works.
Thanks |
30th Sep 2021, 11:13 am | #254 |
Dekatron
Join Date: Apr 2005
Location: North Wales, UK.
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Re: Philips G8 G22K522
Might be worth having a look at the small sub-panel beside the LOPT - the one with the balancing coil on it. Also have a look at the plugs and sockets between the line driver and output panels - pull each wire gently in case there's a bad connection there. Also check the screws on the output transistors for tightness.
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30th Sep 2021, 12:12 pm | #255 |
Nonode
Join Date: Aug 2007
Location: Walsall Wood, Aldridge, Walsall, UK.
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Re: Philips G8 G22K522
Hi!
Another tip I've just remembered in relation to the line output transistor balancing coil – if the core has a hex hole, you can use one of the plastic knob adjusters from the timebase or convergence panel (some of the very early line scan units came with a knob adjuster already clipped to the balance coil) to assist in adjusting this! (Don't forget to give the core of the balance coil a squirt of WD40 before attempting to move it!) I recommend you also remove the line driver transformer from the line scan PCB, clean up it's pins with a fibre–pen, thoroughly tin the pins with fresh solder then refit to the panel – a lot of cases of jumping width and intermittent line transistor failure can be attributed to invisible dry joints on this transformer! If the wirewound line shift potentiometer R5555 in the middle of the panel is scratchy or burnt, turf out the BA148 line shift rectifier and the electrolytic across the control and replace with new ones before you fit a new line shift pot! Chris Williams
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It's an enigma, that's what it is! This thing's not fixed because it doesn't want to be fixed! |
14th Nov 2021, 10:42 pm | #256 |
Octode
Join Date: Jun 2018
Location: Essex, UK.
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Re: Philips G8 G22K522
Hi all, I come bearing news!
I hadn't worked on the G8 for a while as I like to swap sets around when working and make progress slowly on each one. I felt like coming back round to work on the G8 and searching for the dry joint. I believe it was on the balancing coil, but I'm not 100% sure. (Chris, I apologise, I somehow never saw your post until now, but I will certainly look into all of them before I next switch on. I hadn't heard of fibre pens until now but looking into them they sound very helpful, I'll have to get one! I've not yet had to work with R5555 so we'll see) On switch on the EHT rustled up, sounding slightly off, but I expected that, I got a raster which was unlocked, so I tried adjusting L501 which didn't do anything. I switched off to go get a mirror from another room and switched the set on and was met with a horizontally locked test card! The picture rolls vertically very slowly but I'm chuffed to have got a lock on the horizontal. 3 days short of having had and worked on the set for 2 years! There's still faults to be cleared, such as the lines on photo 3( I'm not sure if they're flyback lines, but I don't think they are) But we're finally getting somewhere now we can actually see something on screen! Thanks '77 |
15th Nov 2021, 9:28 pm | #257 |
Octode
Join Date: Jun 2018
Location: Essex, UK.
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Re: Philips G8 G22K522
I have further news!
I realised I had accidentally left the yellow fly lead from the signals board unconnected. I reconnected thinking maybe that could help with the vertical hold, turned the set on and the line frequency was way out, so I disconnected it again to make sure and I had line hold again, but still no vertical lock. I thought to re-read the voltages on TP8 and 9 as I'd changed the IC and wondered what difference it would make. Turned the set off, connected up, and turned on to a fully locked test card, both vertically and horizontally. I was getting a reading 6.2 volts on TP9, but with a locked raster I didn't check TP8. Still some niggling faults but at least we've a picture we can work with! '77 |
21st Nov 2021, 11:38 pm | #258 | |
Octode
Join Date: Jun 2018
Location: Essex, UK.
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Re: Philips G8 G22K522
I've worked on the set some more and managed to get the height and linearity better, the circle is now closer to a circle, not fully yet.
The lines I mentioned are gone, and were in fact fly back lines, but i think I'll need to redo them as it's pretty dark, even with brightness near full. I have a massive purity splodge which needs curing, too big for internal degauss to deal with, so need to find a way to manually degauss. The faults left are red striations on the left of the screen, as seen in the picture. (Manual says to change R5554 but I can't see a 554 on that board) One of the blue convergence pots has broken and so I can't converge properly, but it's not too bad on actual video so not to worried about that at the moment, a broken, but functional volume control and some lines at the top of the screen, also seen in the first picture. Does anyone have any idea what the striations could be, the stock faults list I have says Quote:
Slowly getting there though! Thanks '77 |
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22nd Nov 2021, 10:11 am | #259 |
Dekatron
Join Date: Oct 2003
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Re: Philips G8 G22K522
Check lead dressing first. Striations like that can be caused simply by video leads draping over or too close to the timebase or line scan boards. Perhaps try moving any long leads with an insulated rod (knitting needle) and see if you can improve it.
I was caught out once and had really severe cogging and striations when I was just starting out repairing these at Philips over 40 years ago. The 'old lag' engineer next to me didn't even turn round to look at the fault. He just said 'Is the RGB lead to the CRT base trapped around the signal board'? (it was). I untangled the lead and clipped it up....instant cure! So be aware of silly things like this.
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22nd Nov 2021, 7:11 pm | #260 | |
Octode
Join Date: Jun 2018
Location: Essex, UK.
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Re: Philips G8 G22K522
Thank you, I think there are a couple leads draping over the timebase panel so will have a look into that. Would never think something like that, overlook the simple and assume the worst!
If that doesn't work I also found this Quote:
Thanks '77 |
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