Just got hold of a nice Philips matchline type set that appears to have CRT issues.
Blue comes and goes when it feels like and responds to tube neck taps, which will bring up horizontal stripes of blue....
I remember someone else saying--somewhere that some of these large wide-screen flat faced 32" CRT's had issues.
Is it known what these issues are? H/C short or int open circuit electrodes etc?
Yes I think most of the 'ERF' series had this problem after a time. Not much you can do other than a replacement CRT.....if you can find one.
I was told by someone at the Philips factory in Dreux that the whole gun assembly 'sagged' by some microns during normal use, enough to cause unrepairable shorts. It was towards the end of my time with Philips but I understand that production centres were changed and later tubes were more reliable.
Rich
Thought I would try something....
I wound one loop of wire around the LOPT and disconnected the heater supply from the tube base pins.
I connected the new 'heater-winding' to the tube base-pins and tried it out....
The cathodes were obviously a bit bright, so I tried a few resistors in series. I ended up with a 12 ohm and the cathodes were a nice normal brightness.
There is now no apparent issues with the picture--even tapping the neck doesn't disturb it.....
--Maybe I got lucky this time--Or it will give more problems down the road who knows....
I wonder, If the gun sags, Perhaps turning the CRT upside-down may help--Just a mad idea!
I wonder, If the gun sags, Perhaps turning the CRT upside-down may help--Just a mad idea!
That thought occurred to me too 
Assuming it was feasible, can you reverse the wiring to the scan coil assembly without causing any other issues? Otherwise, you'll have to sit upside down to watch television!
In theory, it should be a simple procedure..... Or, have I missed something here?
Marion
When I was at BBC Evesham, some "Smart Alec" swapped the line scan wires on the camera and the Colour CRT.
The Lecturer was briefly puzzled when he switched from camera to testcard.
FWIW, if you are going to 'play the lopt loop trick' 
, I was once told to strap a 100k resistor from one side of the loop at the crt base to deck (chassis).
This is to stop the now floating heater from building up static charges, an old engineer once told me to do this, and it sort of stuck, not that we did this to customer's sets 
, but we did play with some scrap sets.
One **Philips bodge on an A10 chassis, was to cut the printed pcb track on the relative chassis return connected pin of the heater winding* on the lopt, but again it was a scrap set that ended up being for workshop use.
*The heater winding on this chassis is on it's own two pins and a separate winding, but the chassis pin is connected to a pcb land with the other chassis return pins from other windings.
** I don't mean this was sanctioned by Philips
Reverse the frame scan coil connections would work but possibly the purity may be affected ? Thorn fitted delta gun tubes upside down so that condensation ran into the anode cap, this helped do away with raster correction apparently... 
The only other problem is that the tube base may end up at an odd angle, wiring may not be long enough and the back may not fit depending on clearance and size of tube base pcb.
I would stick to the heater modification, good idea!
Thankfully I had left the trade by the time these beasties started packing up!
Rich.
you'll have to sit upside down to watch television!
Marion
Or turn the set upside down... 
you'll have to sit upside down to watch television!
Marion
Or turn the set upside down...
Aww, come on.... That's way too technical for me at this time of night 
Marion
If you ONLY watch upside down TV and are blindfolded the rest of the time allegedly you'll see it the right way up after a while.
If you ONLY watch upside down TV and are blindfolded the rest of the time allegedly you'll see it the right way up after a while.
Interesting notion, Michael, and to be perfectly honest, I have a telly in my bedroom, which I watch from a lying down position.. After a while (maybe a quarter, to a half hour) I don't really notice any difference.. I just seem to perceive it as being the right way up.
An upside-down screen would be taking things to the extreme, but I could imagine adapting to that too
Marion
Eee gads, You lot are barking!
Its a good point about the static build-up, never thought of that....
I cant believe just how heavy that set is, Damned near killed us hauling it up two flights of stairs!
--If it dies--It'll be going down in pieces rather than complete!
Eee gads, I cant believe just how heavy that set is, Damned near killed us hauling it up two flights of stairs!
--If it dies--It'll be going down in pieces rather than complete!
You want to try moving any of the 36" pure flat type 
There will be an easily accessible ground/chassis point on the crt base pcb print side to connect to. 
Use an old crt heater transformer from a G8 psu. I have done this trick loads of times, no problems
I cant believe just how heavy that set is, Damned near killed us hauling it up two flights of stairs!
--If it dies--It'll be going down in pieces rather than complete!
Believe it or not, a few months ago I was walking home and just passing a neighbour who lives a few doors up from me standing on his doorstep with the remains of a 32" Philips TV spread out at his feet. He looked up as I walked passed looking very white-faced and somewhat trembling. 'Didn't realise how heavy it was. Dropped it and it went off like a bomb'! There wasn't much left of it. Seems that it had fallen face down and hit the corner of the concrete step. Must have been at the weakest part of the faceplate seeing as the bits of glass were over an inch thick in places. My comments? 'Well I'm not going to fix that for you'! I helped him cart the wobbling shattered remains round the side of the house were the local council would collect it.
A few days later I noticed that it had gone and assumed the council had taken it. When I saw him he said 'You know that telly I dropped'? Someone came along in a car, stopped outside and took it the same evening! Saved me calling the council'!
Rich
You know...?
I'm really not surprised to see H/C shorts in these looking at the service-info.
The Cathodes are at 130-140V potential Average.
The Heaters well--One side is grounded.-Therefore, there's 140V potential on that heater insulation. The cathodes in this tube look to be really tiny things too...
The heaters will act as a 'Cathode' of a valve, and the cathode the 'anode' of a diode, Any issues with the alumina insulation will allow current to flow through this crude diode, as the heaters will always be hotter than the cathode surrounding it.--This is a well-known phenomenon.
While grounding the heaters through a 100K would eliminate the static build-up, it would not 'cure' the 'diode' action between H and C.
What I'm thinking is bias the heaters through say that 100k to a positive potential a little above the Cathodes average potential, thus turning 'off' that diode action, and reducing the average strain on the insulation..... 
Most all Cathode driven CTV's (RGB drive as opposed to CDA) use this voltage range for driving the cathodes, at 140V (or max drive voltage) the crt is cut off, and it is only during blanking that the cathodes are driven this high, they may be close during a black screen though.
I notice however you said average, but the average over a 'normal picture' would also be somewhat below this level.
This has never really been a major problem in the past, granted that you would have some small number of failures in all crts of all makes and types, but nowhere near the scale of the problem with this range of Philips tubes (and a number of other types of this make).
SB would know the reasons why, but I recall reading it was a design problem with the physical gun geometry used that was the root cause.
Well--some news....
The set has been running now most of the afternoon and night.
The picture after I did some setting of focus and G2 etc is really extremely good, bright, sharp etc.
--Only one error, maybe relating to the CRT fault, is the grey-scale isnt perfect--although better than some.
Odd effect with the G2 setting position. Set below the point where the grey-scale 'jumps' to sort of correct, it has a slight green tint, but is perfectly stable good and watchable.
At the point where the grey-scale changes (and this point is very critical-literally jumps from slightly greenish low-lights to sort of correct,-still not perfect, but better--
At this setting, The picture has an odd slight brightness instability, and the grey-scale at low scene brightness is constantly varying, particularly on scene changes--not by a lot but noticable if you are looking for it, as if it was hunting for the correct point but can't find it.--I'm thinking the G2 at this point is too high and out of the range of the auto grey-scaling.
The procedure to set the G2 is quite involved--Scopes and all sorts!
--Or if you have the Correct remote--no problem, enter the service-code and select the appropriate option...
There is a procedure involving shorting links on the board to get into the 'SAM' service-menu, but couldn't find the points earlier.
Again--Grey-Scale can be set 'in software' just like the G2 test/setting --If you have the correct remote--Which of course--I dont! 
Of the two above options, Ive settled for a slightly greenish but otherwise perfectly stable non grey-scale varying picture.....
Looks like I'll have to find a better multi-function remote that has a OSD button on it, to get into the service-menu!
You have to be careful with the A1/G2 settings on some Philips sets this can be critical, as some just shutdown (maybe int.) and others blank the picture and then shutdown if the parameters are set outside of the software limits.
What chassis does it use btw ?, and model no. ?
Ah--Yes, That would be a good idea to list the model--wouldnt it!
Its the 32PW9586/05 with a EM3EAA chassis, in a wooden sided cabinet.
The set doesnt seem fussy as regards shut-down no matter where the G2 pot is, from blanked out, to bright white flooded out pic with flyback-lines, so I think we be OK on that point....
