Project [Closed] 1969 Philips G22K511 Missing I/F & LOPT, Conversion
The only thing I might have done differently, would have been to change those remaining aluminium clad electrolytics. Now the panel is in, I'd leave it alone, but I do have recollections of them sometimes giving problems - I think now, it's a matter of suck it and see.
The SS panels were generally more reliable than the DS ones, chiefly on account of the absence of the system switch, but also the lower component count which also simplifies any fault finding.
It's a bit of a shame to unpick all the work you've done in that area, but without a doubt, it removes a non-standard element from the circuit, and puts things back the way they were meant to be - The obvious advantage being that if any issues do arise in the new panel, then stock fault tracing and repair procedures will be easier to apply rather than having to invent new ones as you go. A good move I think.
I find and this was confirmed upon removal from the DS/IF, those low voltage ally caps are perfectly fine both in ESR, value and when given rated voltage not leaky. I only changed them on the DS/IF when we were having trouble with the AGC, as I turned out they were not the culprits. It's the same with Callins, I've lost count the amount of times I get grief for leaving the low voltage ones in place, proof is in the pudding, many 50+ year old TV's happily working with them. Now the High voltage ones are a completely different matter. I fully respect others choices to replace all electrolytics, but It's just not something I do unless absolutely necessary, each to chart their own course I say.
I've built another Beam Limiter module, I didn't want to remove the one from the DS/IF for two reasons. One, I want to keep that board as a fallback solution. Two, the beam limiter I built on that has much more going on, it's also the interface module. Pulling it out would have caused way too much trouble.
All that remains this morning is to revert the brightness circuit.
R1094, R1069, R1093, C1039, X1106 have been re-established, the HT feed we added now removed, all back to SS config. The Beam limiter has been added to the rear of the SS/IF.
Next step; test the new IF.
Next step; test the new IF.
Fingers crossed for that, though I'd expect there to be little likelihood of anything major.
I must admit, I feel happier with that brightness mod reverted to standard, and it's not even mine to worry about, but, the fact that previous pots were fried in the making of this movie, says to me that it may have been an issue again in the future.
I quite agree on those caps, and is just that while the panel was out, and that there were only five of them, it was a convenient juncture at which to replace them. I know there were some that gave issues, way back then, but equally, they may have been faulty manufacture and failed prematurely.
So, with everything else restored to original spec, the only area to concentrate on in the immediate future would be the LOPT conversion, and assuming all is well in that quarter, it's down to the final furlong and basic setting up procedures.
As I fully expected with this snakes & ladders TV, back to square one. No vision and this time no audio thrown into the mix. IF fault-finding tastic!
Well at least with the experiences you had with the DS board it will be fresh in your mind on how to manually bias the AGC stage if needed. Don’t forget that the Gary mentioned that the contrast control set at minimum can shut down the IF.
Does the brightness control have a good range now BTW?
Does the brightness control have a good range now BTW?
Before anything else, just so I can't be nagged 😉 at a later stage about the BF197 LockFit in can 'A', I've replaced it, despite it being perfectly OK. Also, X2625 was OK but left.
Access on the old DS/IF was bad enough to work on, at least once I'd replaced TR2142, TR2143 I could get to the legs to take readings, no such luck with the SS/IF. They are both narrowly located among IF cans. I'm going to replace them and leave longer stubs on the back, at least I can then get access via the back.
I decided to throw my damn principles out the window and replaced all the sand critters, and ejected the ally cans. I want to get past the bloomin IF stage and onto other areas of this TV, it's like being permanently stuck in IF Purgatory.
Now I have sound, however, when I tuned across the band, there's no visible snow, I can sort of guess where the TCF is as it goes very silent. Also, the colourbar can be detected as when I tune over where the colour bar is, I sort of notice a very subtle change in the raster. Scoping the base of T2144, proves the video is there, If I take contrast to a minimum, as Gary stated it does indeed shut down the IF, so I think that's at least now working, it wasn't before.
Trouble is, the brightness seems to have zero effect on the raster, and is probably not helping things here. Also, I've been running with the little beam limiter board in cct, I've been thinking I should probably bypass that for now.
As you can see, the new Siglent Phosphor digi scope really transforms what you can see on the video waveforms now, very analogue-esq.
green=G6 video, purple= locked IMOGen video
No anode volts to the PFL200, R2115 is faulty which is a pain as I fitted a NOS, what are the chance of me picking a duff from the draws. Back at this tomorrow now, Fingers crossed with some good news on the IF.
No anode volts to the PFL200, R2115 is faulty which is a pain as I fitted a NOS, what are the chance of me picking a duff from the draws.
It happens; I know someone who fitted NOS 'high stability' resistors in the grid circuit of a Philips 210 chassis set (it has a 'stabilised' line stage where very high value resistors take the PL504 control grid to HT) and was consequently led a horrendous merry dance, thinking the LOPT was at fault when in fact the NOS resistors were o/c.
Well a new 3.3K cement went in this morning, tested prior to installation and spot on in value. Now? The screen is blank, EHT is there, looks like its cut-off. I'll have to have a look around with the meter to see what's what on the PFL, to be really honest, I'm getting a little sick and tired of this TV now!
Screen grid is spot on at 255V but although I now have some anode its only 117V should be 198V. I'll check the rest of the resistors in the anode cct.
, to be really honest, I'm getting a little sick and tired of this TV now!
You need a medal!
Even with 117v I would have expected to see some slight illumination on the screen, you may need to adjust the cutoff pot. Is there any change in the anode voltage when rotating the brill? If not check the components in the clamp circuit, if there is scope back from the grid to the base of T2144 for video.
you may need to adjust the cutoff pot
Already tried that, no effect.
At that point I had to just walk away and chill in the garden with a coffee as I was liable to take a hammer to the set, so I've not done anything else yet. Well, that's a lie I took CRT readings:-
Cathodes Red=199, Green=202, Blue=200
G2's Red=204, Green=296, Blue=288
G1's Red=-26, Green=-28, Blue=-27
Just powered up to check the anode volts of PFL while adjusting the brightness. I didn't get to do that, as now it's behaving really oddly. Initially anode volts are 316V at switch on then it steadily and rapidly falls to when the EHT comes up, I have only 11.4V
I can understand 316v until the valve starts conducting but with only 11.4v the CRT screen should be rather bright.
Wafts of smoke coming from bottom right of IF board, hard to tell exactly where it's coming from. Powered off, doing a finger test the only component in that area that hurts to touch other than R2111 is R2120, the 10K across the peaking choke L2681. Looks well on its way to a burn up (see photo).
L2681 must be O/C.
I trust the PFL200 is not playing up with shorted internals?
Just thinking out loud because if the anode voltage was missing, the screen may have lit up like a Christmas tree.
It's not open but is only 5.8R the manual states 10R but knowing Philips it's a deviation not documented but does not explain why the 10K would be burning up