Philips 18C636 (KT2) Colour Tv | Restore Help - UK Vintage Radio Repair and Restoration Discussion Forum

MrMetta · 10th Feb 2023, 9:38 am

Dear Friends

I recently purchased a Philips 18C636 (KT2) Color Tv, but it is not in working condition. When plugged in, there is no noise,nothing. I have some experience working with electronics, but have never repaired a television. I would like to learn something from this. What areas of this device should I inspect ?

Some photos are attached.

Thank you

Welsh Anorak · 10th Feb 2023, 10:48 am

Hello and welcome to the forum.

The KT2 wasn't sold in great numbers over here, but was a good reliable TV. One problem I see your TV has is the EHT cable used to arc over as it's crammed into a small space and a repair has been attempted. This won't be your problem however.

First thing is to get a manual which will help you understand what the problem is. It may well just be a simple problem with the mains input - I think there's a surge limiting resitor (like in the KT3) that can fail. I'll dig my manual out.

A pity you're so far away as I have a complete KT2 that has been dropped that would be great for spares. Oh well!

MrMetta · 10th Feb 2023, 11:47 am

Thanks bro,yes I am very far from your place

The issue may be with the mains input, right ? that means I must check that component first

MrMetta · 18th Feb 2023, 5:16 am

Quote:

Originally Posted by Welsh Anorak

I think there's a surge limiting resitor (like in the KT3)

I have circled two resistors in red colour (attached photo) which could be the surge limiting resistor ?

slidertogrid · 18th Feb 2023, 10:53 am

The surge limiter will be a wire-wound resistor with the resistance printed on it. probably that white ceramic rectangular one towards the back of your picture. 4R7 4 watt or thereabouts.
I think the original ones were green so if the one I mentioned is the surge limiter it may have been replaced at some point. It still could be open circuit though they run fairly hot. Check the bridge rectifier which could be four separate diodes for short circuit because if there is a short the replacement resistor will fail.

Maarten · 18th Feb 2023, 11:30 am

I agree, it would be the white resistor and it has been replaced at least once already.

At some point, the degaussing PTC needs to be replaced as well, as it's missing most of its inner workings.

slidertogrid · 18th Feb 2023, 2:18 pm

Opps! I missed that! That may be why the set is dead. Depending on where the thermistor is in the circuit. Has anyone got a diagram of this part of the mains input circuit?

Red to black · 18th Feb 2023, 2:34 pm

Here you go

Red to black · 18th Feb 2023, 3:02 pm

In fact here is the full manual for your model.

slidertogrid · 18th Feb 2023, 3:24 pm

Thanks for the diagram. It looks as if the surge limiter was originally two 10R resistors in parallel maybe they have been replaced with the single ceramic one? The thermistor being broken / missing will only affect degaussing so that can be left for now. Check R597 and R599 they are the surge limiters. I assume F595 the mains fuse is OK? If the surge limiters are Ok see of you have 300V DC across C408.

Maarten · 18th Feb 2023, 3:52 pm

After checking for 300V, if it's present also check for 12V across D404. That's the startup and operating voltage for the oscillator.

MrMetta · 21st Feb 2023, 7:50 am

Quote:

Originally Posted by slidertogrid

The surge limiter will be a wire-wound resistor with the resistance printed on it. probably that white ceramic rectangular one towards the back of your picture. 4R7 4 watt or thereabouts.
I think the original ones were green so if the one I mentioned is the surge limiter it may have been replaced at some point. It still could be open circuit though they run fairly hot. Check the bridge rectifier which could be four separate diodes for short circuit because if there is a short the replacement resistor will fail.

Thanks

Quote:

Originally Posted by Maarten

I agree, it would be the white resistor and it has been replaced at least once already.

At some point, the degaussing PTC needs to be replaced as well, as it's missing most of its inner workings.

Thanks

Quote:

Originally Posted by slidertogrid

Opps! I missed that! That may be why the set is dead. Depending on where the thermistor is in the circuit. Has anyone got a diagram of this part of the mains input circuit?

Thanks

Quote:

Originally Posted by Red to black

In fact here is the full manual for your model.

Thanks

Quote:

Originally Posted by slidertogrid

Thanks for the diagram. It looks as if the surge limiter was originally two 10R resistors in parallel maybe they have been replaced with the single ceramic one? The thermistor being broken / missing will only affect degaussing so that can be left for now. Check R597 and R599 they are the surge limiters. I assume F595 the mains fuse is OK? If the surge limiters are Ok see of you have 300V DC across C408.

Thanks

Quote:

Originally Posted by Maarten

After checking for 300V, if it's present also check for 12V across D404. That's the startup and operating voltage for the oscillator.

Thanks

Thank you all for your valuable comments and documents, which helped me a lot. I didn't power the set up, but I did check all the components you all told me to check.

C408a,C408b,C408c (previous owner has removed them
-Some changes have been made, image attached)

R599 (surge limiting resistor) - Working
D404 - Short (image attached)

In addition,C611 corroded (image attached)

Should replace the cap and diode? Next what should I do?

10th Feb 2023, 9:38 am	#1
MrMetta Diode Join Date: Jan 2023 Location: Kandy, Sir Lanka. Posts: 4	Philips 18C636 (KT2) Colour Tv \| Restore Help Dear Friends I recently purchased a Philips 18C636 (KT2) Color Tv, but it is not in working condition. When plugged in, there is no noise,nothing. I have some experience working with electronics, but have never repaired a television. I would like to learn something from this. What areas of this device should I inspect ? Some photos are attached. Thank you Attached Thumbnails

10th Feb 2023, 10:48 am	#2
Welsh Anorak Dekatron Join Date: Apr 2005 Location: North Wales, UK. Posts: 6,920	Re: Philips 18C636 (KT2) Colour Tv \| Restore Help Hello and welcome to the forum. The KT2 wasn't sold in great numbers over here, but was a good reliable TV. One problem I see your TV has is the EHT cable used to arc over as it's crammed into a small space and a repair has been attempted. This won't be your problem however. First thing is to get a manual which will help you understand what the problem is. It may well just be a simple problem with the mains input - I think there's a surge limiting resitor (like in the KT3) that can fail. I'll dig my manual out. A pity you're so far away as I have a complete KT2 that has been dropped that would be great for spares. Oh well! __________________ Glyn www.gdelectronics.wales

10th Feb 2023, 11:47 am	#3
MrMetta Diode Join Date: Jan 2023 Location: Kandy, Sir Lanka. Posts: 4	Re: Philips 18C636 (KT2) Colour Tv \| Restore Help Thanks bro,yes I am very far from your place The issue may be with the mains input, right ? that means I must check that component first

18th Feb 2023, 10:53 am	#5
slidertogrid Octode Join Date: Apr 2005 Location: Peterborough, Cambridgeshire, UK. Posts: 1,898	Re: Philips 18C636 (KT2) Colour Tv \| Restore Help The surge limiter will be a wire-wound resistor with the resistance printed on it. probably that white ceramic rectangular one towards the back of your picture. 4R7 4 watt or thereabouts. I think the original ones were green so if the one I mentioned is the surge limiter it may have been replaced at some point. It still could be open circuit though they run fairly hot. Check the bridge rectifier which could be four separate diodes for short circuit because if there is a short the replacement resistor will fail. Last edited by slidertogrid; 18th Feb 2023 at 10:59 am.

18th Feb 2023, 11:30 am	#6
Maarten Dekatron Join Date: Dec 2007 Location: Haarlem, Netherlands Posts: 4,199	Re: Philips 18C636 (KT2) Colour Tv \| Restore Help I agree, it would be the white resistor and it has been replaced at least once already. At some point, the degaussing PTC needs to be replaced as well, as it's missing most of its inner workings.

18th Feb 2023, 2:18 pm	#7
slidertogrid Octode Join Date: Apr 2005 Location: Peterborough, Cambridgeshire, UK. Posts: 1,898	Re: Philips 18C636 (KT2) Colour Tv \| Restore Help Opps! I missed that! That may be why the set is dead. Depending on where the thermistor is in the circuit. Has anyone got a diagram of this part of the mains input circuit?

18th Feb 2023, 3:24 pm	#10
slidertogrid Octode Join Date: Apr 2005 Location: Peterborough, Cambridgeshire, UK. Posts: 1,898	Re: Philips 18C636 (KT2) Colour Tv \| Restore Help Thanks for the diagram. It looks as if the surge limiter was originally two 10R resistors in parallel maybe they have been replaced with the single ceramic one? The thermistor being broken / missing will only affect degaussing so that can be left for now. Check R597 and R599 they are the surge limiters. I assume F595 the mains fuse is OK? If the surge limiters are Ok see of you have 300V DC across C408.

18th Feb 2023, 3:52 pm	#11
Maarten Dekatron Join Date: Dec 2007 Location: Haarlem, Netherlands Posts: 4,199	Re: Philips 18C636 (KT2) Colour Tv \| Restore Help After checking for 300V, if it's present also check for 12V across D404. That's the startup and operating voltage for the oscillator.