Philips K35. Bright Blue Picture. - UK Vintage Radio Repair and Restoration Discussion Forum

cornboats · 24th Nov 2006, 10:55 am

My Philips22CS3745/05T -K35 chassis only gives out a bright blue picture -no sound. I've checked all voltages on plug-in boards as per manual.

cornboats · 24th Nov 2006, 6:23 pm

I didn't realise forum can't handle xl files so i've changed format to a word doc.
I hope you can read ok.
Thanks for showing an interest.
Dave

murphyv310 · 24th Nov 2006, 9:47 pm

Hello.
You say you have a bright blue picture. Can you see any picture information? Or do you have a blue "raster".
You also need a scope, it's the best tool you can have, you can throw your meter away the scope will tell you all you need to know.

Do you have a diagram for the set? It is possible you have two separate faults.

Trevor

Heatercathodeshort · 24th Nov 2006, 11:03 pm

Hello Dave,
As Trevor suggests you may well have two faults here especially if someone has 'had a go' before you got to it.
You will need a meter to check the basics. You need to check that all three A1 switches are turned on and the presets are turned well up.
The CRT cathode voltages will need to be noted. They should all read the same approximately. Around 140-160v, and you should see all three guns, not just the blue.
Are you sure the loudspeaker is turned on? Most K35's have a very small switch near the headphone socket that is very easily overlooked. Thats a start anyway. Regards John.

cornboats · 25th Nov 2006, 11:02 am

Trevor.
I've got the manual which includes a schematic.
I've got a scope and have connected it to the points indicated on the drawing but don't get the same result.
My lecturer says its because some of signals are video. I'm using the scope off a transformer supply as -chassis is live.

Picture is just plain blueish with a few white lines across. No sound. Sound switch is on.

Thanks for showing an interest.

cornboats · 25th Nov 2006, 11:10 am

John. These 3 presets you've mentioned; are these the RGB variable pots that adjust the amount of colour?

When you say I should see all three guns - could you elaborate?

Speaker is turned on- When I was taking voltages with meter, sound came on for a brief second, which lecturer says was probably stray signal!

I appreciate your interest.

Danny · 25th Nov 2006, 12:58 pm

Hi all
Reading should be made with respect to deck; the negative meter connection is best taken from the tuner case as the aerial socket is isolated from the chassis.

Recheck the voltages with respect to the tuner case and what's on the crt cathodes; this will tell all.

As if the blue transistor is short, this will give bright blue raster and mute the other guns.
A quick check is to remove the blue driver transistor on the RGB board and switch on: you may be lucky and get a picture (without blue of course).

Danny

cornboats · 27th Nov 2006, 10:13 am

Danny.
I soldered a lead onto the tuner case and have used as neg for scope and meter readings.
I took RGB voltages at crt ,before pots. All 3 were about 140v. Design 135v.
Would you still disconnect blue driver transistor?

david

flyingtech55 · 27th Nov 2006, 11:06 am

Cornboats

Was the set working normally and then failed while it was in use or have you acquired this set in a non-working condition?

Secondly, has anyone else 'had a go' at fixing this set?

TimR

cornboats · 27th Nov 2006, 6:47 pm

TimR -We've had the set since new.

I changed fusible resistor on power supply board which had blown about 1 year ago. No fault apart from this found.
I changed posistor in degauss circuit which was causing pink tinge about 6 months ago.
I changed standby battery (1.5v) about 3 months ago because set was loosing tuner info every time set was shutdown.

The set was running OK giving great picture. I used it the previous day then turned it on the following day only to get blank screen and no sound.

Thanks for your interest, if you can shed any light on problem I would appreciate any comments.

Danny · 28th Nov 2006, 1:28 am

Hi
3 stock faults you listed here. If this is the first time these have been replaced then that's not bad.

I am puzzled why all the cathodes are the same and you have a blue raster. Are you sure you are testing the cathodes?
If you want to do a quick check then unsolder the blue cathode and make sure it's clear from contact with the print, and switch on.
If the blue is still present then it's a heater to cathode short in the tube
but if it gives a picture then you are away.

Just a thought; it's a remote set and my memory has just started to glow.

No sound no picture - have you tried the remote to brighten up and turn the sound up? Try it then let us know what happens.

Danny

cornboats · 30th Nov 2006, 10:25 am

All interested parties.

I took rgb voltages directly off crt pins and readings are 152-153V.
I tried to have a look with scope but couldn't get anything.

I checked remote but no difference made. When I manually turned down brightness on set the bright blue goes to dark red with loads of horizontal white lines. The sound then comes up to loud hum.

I took blue driver out as Danny suggested but I couldn't detect any difference.

Could anyone suggest a reason for not being able to get scope pictures?
How do I disconnect blue cathode?

Danny · 30th Nov 2006, 5:31 pm

Hi
I still haven't found my manual, but will have another look tomorrow but
just to clarify things, is there a picture in the blue raster?
When you turn down the brightness what are the cathode volts?
You say the sound comes up to loud hum; do you mean it's like a mains hum?
Is there any normal sound present?
At the top of the pcb above the hole that the CRT comes through, you will find a small electrolytic capacitor. I think it's a 4.7uf at 250v' this is the supply to the RGBs, and sometimes strange things used to happen when this went low capacity.
It should have a good 200volts across it when the set is running.

Now on the small PCB to the left top if I'm right, it's got a big chip on it?
If so, on the PCB behind you should be able to see the RGB drives.
If you scope these there should be video present.

Try adjusting the contrast while scoping the RGB. I bet there will be no video, and the big chip may have failed; they did vary occasionally but the above cap has strange effects on the RGBs, so give it a try.

Danny

flyingtech55 · 30th Nov 2006, 8:06 pm

Hi Cornboats

Its difficult to diagnose from a distance especially when you don't know the person's experience or knowledge. When you're in the trade you knew when (say) Jimmy 'phoned you could suggest something and off he'd go a sort it out. When another engineer rang you had to be careful because you knew he wasn't able to 'interpret' what you were telling him and was liable to be literal with not good results.

However....what I would suggest you do is check for the HT supply on the RGBs like Danny said then 'dry' the blue cathode pin (or cut the print) on the CRT base panel. Connect the PIN (not the land) to the red or green cathode pin on the CRT base panel with a short length of wire ie you're driving two cathodes from one drive.

If you still have a bright blue screen, the chances are that the CRT has shorted. If however, the blue flooding stops then you can investigate the drive circuitry on the blue channel.

Ignore the no-sound symptom for now. Until you can see a raster on the screen you can't really see what's going on. The no sound is probably just muting.

HTH

TimR

cornboats · 7th Dec 2006, 11:16 am

I have a result!

I worked through everyone's suggestions and telemedic's pulled up trumps.

A 630mamp fuse on the ac transformer board- tucked away behind the main board so you can't see or get to it - had blown.
Once replaced the set came up with full picture and sound.

Does anybody have drawing that relates to 240v ac transformer board as this is not included in main drawing or service manual?
Thanks to everyone's interest.

I have now a secondary fault. I decided to check all the scope pictures against the drawing and started with termninal 14 on power supply board.
The scope wasn't giving a clear picture so I was adjusting the probe hook on the flylead I'd soldered onto the pin. Making and breaking the hook with the lead made the set power down & up a couple of times before going dead. I checked all three fuses on the set and found a 2amp on the supply board had blown.
I replaced with a slow blow but set is still dead.

10W white ceramic resistor on supply board is ok.
Set will not come in not standby when set switch is turned on.
Anybody have any ideas??

24th Nov 2006, 10:55 am	#1
cornboats Triode Join Date: Nov 2006 Location: Bromsgrove Posts: 31	Philips K35. Bright Blue Picture. My Philips22CS3745/05T -K35 chassis only gives out a bright blue picture -no sound. I've checked all voltages on plug-in boards as per manual. Last edited by Mike Phelan; 5th Oct 2007 at 8:33 am.

24th Nov 2006, 9:47 pm	#3
murphyv310 Dekatron Join Date: Sep 2006 Location: Kilmarnock, Ayrshire, UK. Posts: 5,422	Re: Philips K35. Bright Blue Picture. Hello. You say you have a bright blue picture. Can you see any picture information? Or do you have a blue "raster". You also need a scope, it's the best tool you can have, you can throw your meter away the scope will tell you all you need to know. Do you have a diagram for the set? It is possible you have two separate faults. Trevor __________________ Cheers, Trevor. MM0KJJ. RSGB, GQRP, WACRAL, K&LARC. Member

24th Nov 2006, 11:03 pm	#4
Heatercathodeshort Dekatron Join Date: Jun 2005 Location: Warnham, West Sussex. 10 miles south of DORKING. Posts: 9,147	Re: Philips K35. Bright Blue Picture. Hello Dave, As Trevor suggests you may well have two faults here especially if someone has 'had a go' before you got to it. You will need a meter to check the basics. You need to check that all three A1 switches are turned on and the presets are turned well up. The CRT cathode voltages will need to be noted. They should all read the same approximately. Around 140-160v, and you should see all three guns, not just the blue. Are you sure the loudspeaker is turned on? Most K35's have a very small switch near the headphone socket that is very easily overlooked. Thats a start anyway. Regards John.

25th Nov 2006, 11:02 am	#5
cornboats Triode Join Date: Nov 2006 Location: Bromsgrove Posts: 31	Re: Philips K35. Bright Blue Picture. Trevor. I've got the manual which includes a schematic. I've got a scope and have connected it to the points indicated on the drawing but don't get the same result. My lecturer says its because some of signals are video. I'm using the scope off a transformer supply as -chassis is live. Picture is just plain blueish with a few white lines across. No sound. Sound switch is on. Thanks for showing an interest.

25th Nov 2006, 11:10 am	#6
cornboats Triode Join Date: Nov 2006 Location: Bromsgrove Posts: 31	Re: Philips K35. Bright Blue Picture. John. These 3 presets you've mentioned; are these the RGB variable pots that adjust the amount of colour? When you say I should see all three guns - could you elaborate? Speaker is turned on- When I was taking voltages with meter, sound came on for a brief second, which lecturer says was probably stray signal! I appreciate your interest.

25th Nov 2006, 12:58 pm	#7
Danny Heptode Join Date: Jul 2003 Location: North Walsham, Norfolk, UK. Posts: 516	Re: Philips K35. Bright Blue Picture. Hi all Reading should be made with respect to deck; the negative meter connection is best taken from the tuner case as the aerial socket is isolated from the chassis. Recheck the voltages with respect to the tuner case and what's on the crt cathodes; this will tell all. As if the blue transistor is short, this will give bright blue raster and mute the other guns. A quick check is to remove the blue driver transistor on the RGB board and switch on: you may be lucky and get a picture (without blue of course). Danny

27th Nov 2006, 10:13 am	#8
cornboats Triode Join Date: Nov 2006 Location: Bromsgrove Posts: 31	Re: Philips K35. Bright Blue Picture. Danny. I soldered a lead onto the tuner case and have used as neg for scope and meter readings. I took RGB voltages at crt ,before pots. All 3 were about 140v. Design 135v. Would you still disconnect blue driver transistor? david

27th Nov 2006, 11:06 am	#9
flyingtech55 Octode Join Date: Nov 2005 Location: Ayrshire, UK. Posts: 1,096	Re: Philips K35. Bright Blue Picture. Cornboats Was the set working normally and then failed while it was in use or have you acquired this set in a non-working condition? Secondly, has anyone else 'had a go' at fixing this set? TimR

27th Nov 2006, 6:47 pm	#10
cornboats Triode Join Date: Nov 2006 Location: Bromsgrove Posts: 31	Re: Philips K35. Bright Blue Picture. TimR -We've had the set since new. I changed fusible resistor on power supply board which had blown about 1 year ago. No fault apart from this found. I changed posistor in degauss circuit which was causing pink tinge about 6 months ago. I changed standby battery (1.5v) about 3 months ago because set was loosing tuner info every time set was shutdown. The set was running OK giving great picture. I used it the previous day then turned it on the following day only to get blank screen and no sound. Thanks for your interest, if you can shed any light on problem I would appreciate any comments.

28th Nov 2006, 1:28 am	#11
Danny Heptode Join Date: Jul 2003 Location: North Walsham, Norfolk, UK. Posts: 516	Re: Philips K35. Bright Blue Picture. Hi 3 stock faults you listed here. If this is the first time these have been replaced then that's not bad. I am puzzled why all the cathodes are the same and you have a blue raster. Are you sure you are testing the cathodes? If you want to do a quick check then unsolder the blue cathode and make sure it's clear from contact with the print, and switch on. If the blue is still present then it's a heater to cathode short in the tube but if it gives a picture then you are away. Just a thought; it's a remote set and my memory has just started to glow. No sound no picture - have you tried the remote to brighten up and turn the sound up? Try it then let us know what happens. Danny

30th Nov 2006, 10:25 am	#12
cornboats Triode Join Date: Nov 2006 Location: Bromsgrove Posts: 31	Re: Philips K35. Bright Blue Picture. All interested parties. I took rgb voltages directly off crt pins and readings are 152-153V. I tried to have a look with scope but couldn't get anything. I checked remote but no difference made. When I manually turned down brightness on set the bright blue goes to dark red with loads of horizontal white lines. The sound then comes up to loud hum. I took blue driver out as Danny suggested but I couldn't detect any difference. Could anyone suggest a reason for not being able to get scope pictures? How do I disconnect blue cathode?

30th Nov 2006, 5:31 pm	#13
Danny Heptode Join Date: Jul 2003 Location: North Walsham, Norfolk, UK. Posts: 516	Re: Philips K35. Bright Blue Picture. Hi I still haven't found my manual, but will have another look tomorrow but just to clarify things, is there a picture in the blue raster? When you turn down the brightness what are the cathode volts? You say the sound comes up to loud hum; do you mean it's like a mains hum? Is there any normal sound present? At the top of the pcb above the hole that the CRT comes through, you will find a small electrolytic capacitor. I think it's a 4.7uf at 250v' this is the supply to the RGBs, and sometimes strange things used to happen when this went low capacity. It should have a good 200volts across it when the set is running. Now on the small PCB to the left top if I'm right, it's got a big chip on it? If so, on the PCB behind you should be able to see the RGB drives. If you scope these there should be video present. Try adjusting the contrast while scoping the RGB. I bet there will be no video, and the big chip may have failed; they did vary occasionally but the above cap has strange effects on the RGBs, so give it a try. Danny

30th Nov 2006, 8:06 pm	#14
flyingtech55 Octode Join Date: Nov 2005 Location: Ayrshire, UK. Posts: 1,096	Re: Philips K35. Bright Blue Picture. Hi Cornboats Its difficult to diagnose from a distance especially when you don't know the person's experience or knowledge. When you're in the trade you knew when (say) Jimmy 'phoned you could suggest something and off he'd go a sort it out. When another engineer rang you had to be careful because you knew he wasn't able to 'interpret' what you were telling him and was liable to be literal with not good results. However....what I would suggest you do is check for the HT supply on the RGBs like Danny said then 'dry' the blue cathode pin (or cut the print) on the CRT base panel. Connect the PIN (not the land) to the red or green cathode pin on the CRT base panel with a short length of wire ie you're driving two cathodes from one drive. If you still have a bright blue screen, the chances are that the CRT has shorted. If however, the blue flooding stops then you can investigate the drive circuitry on the blue channel. Ignore the no-sound symptom for now. Until you can see a raster on the screen you can't really see what's going on. The no sound is probably just muting. HTH TimR

7th Dec 2006, 11:16 am	#15
cornboats Triode Join Date: Nov 2006 Location: Bromsgrove Posts: 31	Re: Philips K35. Bright Blue Picture. I have a result! I worked through everyone's suggestions and telemedic's pulled up trumps. A 630mamp fuse on the ac transformer board- tucked away behind the main board so you can't see or get to it - had blown. Once replaced the set came up with full picture and sound. Does anybody have drawing that relates to 240v ac transformer board as this is not included in main drawing or service manual? Thanks to everyone's interest. I have now a secondary fault. I decided to check all the scope pictures against the drawing and started with termninal 14 on power supply board. The scope wasn't giving a clear picture so I was adjusting the probe hook on the flylead I'd soldered onto the pin. Making and breaking the hook with the lead made the set power down & up a couple of times before going dead. I checked all three fuses on the set and found a 2amp on the supply board had blown. I replaced with a slow blow but set is still dead. 10W white ceramic resistor on supply board is ok. Set will not come in not standby when set switch is turned on. Anybody have any ideas??