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Old 9th Oct 2020, 11:59 am   #101
19Seventy7
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Default Re: Philips G8 G22K522

I was thinking the TBS530 was a transistor, whereas the TBA530 was the chip , you learn something new everyday

I'd be curious to see one with the subpanel - that's if any do even exist now then

I did actually discharge the cap every time before testing it, which is why I think it might be on it's way out. It's curious though really, thinking about it now, that's the only board that's clearly had repairs done to it, as it's got different capacitors to the rest of the boards.

Unfortunately I've not got a 'scope, not that I even know how to use one yet, but it's not got an TAA700 but a TBS5500

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Old 9th Oct 2020, 12:53 pm   #102
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Default Re: Philips G8 G22K522

The TYAA700 was a very early IC and was soon superceded. I'll have a look in my manual as I should have the supplement for the later version IF panel. As I said earlier, this is an unusual fault for a G8.
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Old 9th Oct 2020, 1:06 pm   #103
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Default Re: Philips G8 G22K522

Just a quick edit, the chip in my board where a TAA700 should be is a TBA5500, not TBS, made the exact same mistake. I don't know if you realised that or not but thought best to clarify.

I've also just realised that there's been a bit of a burn up on the board before, which looks to have literally burned right through the board, but it's all been bridged back with solder cemented within glue, probably why caps have had to been changed on that board and possibly a, if not the, cause to this issue

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Old 9th Oct 2020, 1:12 pm   #104
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Default Re: Philips G8 G22K522

Always worth removing the board and checking over the repair with a magnifying light. You never know, a wire might have come off that's still glued in position.
I assumed it was a TBA550.
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Old 9th Oct 2020, 1:22 pm   #105
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Default Re: Philips G8 G22K522

Sorry should've clarified, the solder is the wire in the glue itself, but it doesn't look to be broken, and the amount of dirt sitting on it, i'd assume it was done years ago. Again another mistake I've made, poor eyesight, it's 550Q, if that makes any difference?

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Old 9th Oct 2020, 1:36 pm   #106
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Default Re: Philips G8 G22K522

No -the suffix Q only refers to the pin layout. It's an old version meaning Quad in-line, as opposed to the more common dual in-ine.
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Old 9th Oct 2020, 1:54 pm   #107
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Default Re: Philips G8 G22K522

Oh right, never knew that, not that I know much about chips and transistors anyway

Again, you learn something new everyday

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Old 22nd Oct 2020, 10:38 pm   #108
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Default Re: Philips G8 G22K522

So I've changed the 4uF decoupler, which is now 4.4uF which seems to have helped because I now have a stable picture of sorts (Attached, it does look a bit better in person)

I found a list of stock faults and it said no line sync could be either C4497 at 0.15uF, C2170 at 10uF or IC2001 which is TAA700.

I can't find any C4497 or C2170, but can find a C497 and C170, C497 is tropical fish capacitor but the one installed is rated 0.047uF according to a online calculator is 0.047uF (Yellow, violet, orange, black, red). C170 is 10uF in the set.

My guess now is maybe that me replacing the decoupling cap is that I've maybe uncovered a potentially incorrect repair, fitting a 0.047uF cap?

My question being now is am I right in thinking C4497 on the list is C497 in my set or am I looking in the wrong place? C497 is just above the line hold coil.
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Old 22nd Oct 2020, 10:50 pm   #109
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Default Re: Philips G8 G22K522

I've got this bug buzzing around in my head. Back in 1983 / 84 I worked on these a lot at Visionhire. The bug is telling me that C4497 is C497 on PCB number 4. Likewise with C2170 on PCB number 2. It was 36 years ago so........
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Old 22nd Oct 2020, 11:02 pm   #110
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Default Re: Philips G8 G22K522

The full service manual would have explained the capacitor designation. Philips tended to use a code for each separate PCB....in your case the PCB would have been 2 and C170 would have been 2170 (or C170 on PCB2). There could be a C170 on the line timbase PCB but in that case it would be 4170. So the answer to your question is yes. C497 on PCB4 is C4497. It might be confusing to people not used to it but after a short while you get to know. PCB6 was usually the power supply so if I saw a capacitor marked 6650 I'd look for C650 on the power supply.
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Old 22nd Oct 2020, 11:03 pm   #111
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Default Re: Philips G8 G22K522

Quote:
Originally Posted by trickie_dickie View Post
I've got this bug buzzing around in my head. Back in 1983 / 84 I worked on these a lot at Visionhire. The bug is telling me that C4497 is C497 on PCB number 4. Likewise with C2170 on PCB number 2. It was 36 years ago so........

You've got it!!!
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Old 22nd Oct 2020, 11:16 pm   #112
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Default Re: Philips G8 G22K522

From the picture in post 108 it appears replacing the 4uF capacitor has changed the frequency of the line oscillator by quite a bit, I suspect it’s a small electrolytic you’ve fitted and will be polarised. If you’re certain it’s been fitted the correct way round then try adjusting the core of L501 on the timebase board to bring it back to the correct frequency and see if it will lock before changing parts more parts.

BTW 4.4uF is an odd value nowadays, is it a modern type or old stock you have used?

John.

Last edited by jayceebee; 22nd Oct 2020 at 11:26 pm. Reason: Cap question
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Old 23rd Oct 2020, 12:19 am   #113
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Default Re: Philips G8 G22K522

Wasn't expecting that many replies at once

I thought the number after the C would be the board number, but it didn't make sense to me that 2170 is on the 3rd board, but 4497 on 4th with the PSU board as number 1, not 6. So if the chrominance board was 1, that'd make 2170 correct, but 4497 incorrect, that definitely threw me off at first, but figured it.

Quote:
From the picture in post 108 it appears replacing the 4uF capacitor has changed the frequency of the line oscillator by quite a bit, I suspect it’s a small electrolytic you’ve fitted and will be polarised. If you’re certain it’s been fitted the correct way round then try adjusting the core of L501 on the timebase board to bring it back to the correct frequency and see if it will lock before changing parts more parts.

BTW 4.4uF is an odd value nowadays, is it a modern type or old stock you have used
That's the best I can get out of it with 4.4uF, better than I could with the 4uF capacitor that was in place and read faulty anyway, but you're right, how I missed that I don't know, but I've put it in the wrong way round. I'll sort that out in the morning and let you all know

I had to combine two modern 2.2uF caps to get 4.4uF, the closest I could get to 4uF.

Thanks all for the help
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Old 23rd Oct 2020, 11:15 am   #114
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Default Re: Philips G8 G22K522

A 4.7uF would work fine - or should.
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Old 23rd Oct 2020, 11:17 am   #115
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Default Re: Philips G8 G22K522

Sorry to ask, but are the two caps in parallel as they should be or in series?
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Old 23rd Oct 2020, 4:20 pm   #116
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Default Re: Philips G8 G22K522

I think the 4.4uF is working alright, there’s no clear difference between the original 4uF and this 4.4uF now I’ve rotated it to work.

I’m not sure what it’d be called but i’ve connected the negative of one to the positive of the other and then soldered it into place.

I’m going to check C4497 and C2170 and see how that goes.

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Old 23rd Oct 2020, 4:24 pm   #117
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Default Re: Philips G8 G22K522

No - you need to put the two in parallel, the two positives together and the two negatives. I think you've put them in series. Rule - to increase the value of resistors, chain them in series. To increase the value of capacitors, put them in parallel.
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Old 23rd Oct 2020, 4:31 pm   #118
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Default Re: Philips G8 G22K522

So you have connected them in series, this will half the value you need (2 X 2.2 uF in series = 1.1 uF), either stick a 4.7uF one in place, or both of your 2.2uF together the correct polarity in place of the original.
Do an internet search of capacitors in parallel and series, it works the opposite way to resistors in the same combinations.

Edit: cross posted with Glyn
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Last edited by Red to black; 23rd Oct 2020 at 4:32 pm. Reason: cross posted
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Old 23rd Oct 2020, 4:53 pm   #119
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Default Re: Philips G8 G22K522

Oh I didn’t know that. I had just assumed it’d be the same as resistors and with the electricity flowing from negative to positive. That’s definitely taught me something. I’ll keep that in mind. In fact I think I have a 4.7uF in stock which I can use, it’ll be neater to look at, at least.

It wont be for a few days now, but i’ll let you know how I get on.

Thanks all for the help, appreciate it
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Old 4th Nov 2020, 10:40 pm   #120
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Default Re: Philips G8 G22K522

And so the fun continues

I went to put the two 2.2uFs in parallel to create the 4.4uF, but as it happens, the capacitors were having none of this and ones leg fell off in soldering, so as Welsh Anorak suggested, I ordered some 4.7uFs and waited for their arrival.

I fitted one today, re-seated the board, plugged in and switched on. CRACK! switch off and pull the plug, can hear a very quiet fizzling from what sounded like the CRT anode when unplugged, this has since stopped, but I'm wondering if that's just the last of the EHT fizzling away and is normal and I've just never noticed it before?

Turns out that the crack was a transistor blowing, T4524 on the timebase panel, everything else is visually okay. Not sure if this would've blown on its own accord or if something has overloaded it. The only mention of it I can find in "Servicing the Philips G8 chassis" (Television - June 1978) is its function of amplifying line and field frequency pulses.

I'd check to see how much voltage T4524 was receiving to see if it was overloaded, but I don't know how much voltage it should be receiving to compare it to, and if so, to trace it back?

Thanks
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