Brand new Philips KT3 with weak CRT - UK Vintage Radio Repair and Restoration Discussion Forum

Jimmyhaflinger · 9th Dec 2007, 8:06 pm

Hi you all,

I have just found a 1983 Philips 16 inch KT3 portable in a closing repair shop, the set is totally mint, like new, not a speck of dust or any sign of use inside this set!

This has to be the last KT3 incarnation, the "Super Selection" series, unlike the older KT3s which used a black matrix CRT, this one has a traditional aluminium matrix CRT

Oddly, it has a terrible picture, the blue gun taker almost 20 minutes to come on, then it's weak even with the blue controls all the way up, and then any blue object looks dull and has quite a lot of smearing.

Any suggestions on possible electronic problems before i go ahead and blast the CRT?

Thanks
Francesco, Italy

Hybrid tellies · 9th Dec 2007, 8:20 pm

It may not be the tube, it could be sluggish electrolytic caps in the blue output or drive.
Try leaving it running for a few hours to see what happens.
Brilliant sets these so its worth persevering with.

Jimmyhaflinger · 9th Dec 2007, 11:27 pm

I'll try to swap the video output card with one borrowed from a perfectly working KT3 i have, i'll let you know.

Steve_P · 9th Dec 2007, 11:32 pm

Is this the Philips Set with those modules on the tube base that do funny things...

Cheers,

Steve P

Jimmyhaflinger · 9th Dec 2007, 11:37 pm

No, this one has just a few resistors on the CRT socket board, in the KT3 the video amps are on a plug in card on the main chassis.

AFAIK the Philips chassis with the (thick film) output modules on the CRT socket board is the K12

Maarten · 10th Dec 2007, 2:13 am

It could be 'lazy cathodes'. In that case, things may improve if you let the set play for several hours. I also know of certain TV sets where the tubes were apparently not driven hard enough and the emission of one or more cathodes would be way off after a few years of usage, which could be fixed by applying 12 volt to the heaters for a few minutes.

Dr-Watts · 10th Dec 2007, 8:38 am

S/C the choke or chokes on the tube base and run it for a day or so, that usually cheers em up

Dr. Dave

Jimmyhaflinger · 10th Dec 2007, 8:52 am

I have just swapped the video output card, but the blue is still weak, and i still have the heavy blue smearing around highlights.

The smearing gets far worse when the set is warm, after a half hour or so, and no matter how you adjust the bias and drive, you just can't get the CRT to display decent colours

At this point i'm starting to realize that this set is still brand new and unused because it had a bad CRT out of the box

Francesco

Maarten · 10th Dec 2007, 10:34 pm

Quote:

Originally Posted by Jimmyhaflinger

I have just swapped the video output card, but the blue is still weak, and i still have the heavy blue smearing around highlights.

The smearing gets far worse when the set is warm, after a half hour or so, and no matter how you adjust the bias and drive, you just can't get the CRT to display decent colours

At this point i'm starting to realize that this set is still brand new and unused because it had a bad CRT out of the box

Francesco

Not necessarily, I just realised, you could try and measure the supply voltage to the cathode drivers. If this is low, you will get the same symptoms you're experiencing. Smearing is an indication of the drivers driven into saturation and thus not switching off fast enough. This also happens if the feedback circuit (not sure if the KT3 even has this) wants to increase cathode current beyond the ability of the drivers. In that case, turning up the G2 voltage may help as well.

flyingtech55 · 11th Dec 2007, 11:04 am

Hi

Check the A1 voltage. If it's low you get these symptoms because of saturating the RGBs as Maarten says.

The thing is, you don't know the history of the set. It may be brand new and the tube was faulty from new, the tube may have deteriorated through non use, the set may have been 'robbed', it may have been a 'hanger queen' or there's nothing fundamentally wrong with the set, it's just been fiddled with so much in the past that it needs to be set properly by the book.

However, it is suspicious that it's new in its box and was never sold.

HTH

TimR

Jimmyhaflinger · 11th Dec 2007, 8:10 pm

I have measured a few voltages,

I have 163 volts on the RGB output card, (it should be 155) and 400 volts on the G2

With 400 volts on the G2 the picture looks normally bright, but with a lot of blue smearing, if i turn up the G2 voltage to a point just before the flyback lines become visible, the smearing gets better but at this point the picture is ridiculously bright and dull.

Francesco

Jimmyhaflinger · 12th Dec 2007, 8:29 am

I have left the set on all night with the shorted chokes, this improved the emission of the blue gun and now i have a good greyscale and it no longer takes 20 minutes for the blue to wake up.

But... the smearing has got far worse! the blue is now smearing for over an inch and now i have some red smearing too...

Francesco

flyingtech55 · 12th Dec 2007, 11:31 am

Hi Jimmyhaflinger

It's beginning to look like the CRT is duff. Are the RGB outputs on the CRT base PCB or are they on the main PCB?

TimR

Jimmyhaflinger · 13th Dec 2007, 10:24 pm

Well, KT3s as well as Kt4s-K40s are still quite common here, and it's still relatively easy to find them, so i think i'll find a good CRT sooner or later.

I think the same CRT was also used in CTX sets too.

What's getting really difficult to find are K30 and K35 sets, apparently, most developed weak CRTs and were mass scrapped the late 90s, i used to find tons of them, they rarely had a decent picture, and the few that did usually had gouged screens or busted cabinets

I should have kept some of them, but i was mainly interested in K9, K11 and K12 sets back then... now they're all gone and a 1983 "spatial stereo super selection" is one of my top wishes now...

9th Dec 2007, 8:06 pm	#1
Jimmyhaflinger Heptode Join Date: Feb 2007 Location: La Spezia, Italy Posts: 834	Brand new Philips KT3 with weak CRT Hi you all, I have just found a 1983 Philips 16 inch KT3 portable in a closing repair shop, the set is totally mint, like new, not a speck of dust or any sign of use inside this set! This has to be the last KT3 incarnation, the "Super Selection" series, unlike the older KT3s which used a black matrix CRT, this one has a traditional aluminium matrix CRT Oddly, it has a terrible picture, the blue gun taker almost 20 minutes to come on, then it's weak even with the blue controls all the way up, and then any blue object looks dull and has quite a lot of smearing. Any suggestions on possible electronic problems before i go ahead and blast the CRT? Thanks Francesco, Italy

9th Dec 2007, 8:20 pm	#2
Hybrid tellies Nonode Join Date: Jan 2004 Location: 1966-1976 Coverack in Cornwall and Helston Cornwall. 1976-present Bristol/Bath area. Posts: 2,967	Re: Brand new Philips KT3 with weak CRT It may not be the tube, it could be sluggish electrolytic caps in the blue output or drive. Try leaving it running for a few hours to see what happens. Brilliant sets these so its worth persevering with. __________________ Simon BVWS member

9th Dec 2007, 11:27 pm	#3
Jimmyhaflinger Heptode Join Date: Feb 2007 Location: La Spezia, Italy Posts: 834	Re: Brand new Philips KT3 with weak CRT I'll try to swap the video output card with one borrowed from a perfectly working KT3 i have, i'll let you know. Last edited by Jimmyhaflinger; 9th Dec 2007 at 11:33 pm.

9th Dec 2007, 11:32 pm	#4
Steve_P Dekatron Join Date: Sep 2003 Location: Bolton, Greater Manchester, UK. Posts: 6,644	Re: Brand new Philips KT3 with weak CRT Is this the Philips Set with those modules on the tube base that do funny things... Cheers, Steve P __________________ If we've always had it, why is the Car Boot open? You're not sneaking another Old TV in are you...?

9th Dec 2007, 11:37 pm	#5
Jimmyhaflinger Heptode Join Date: Feb 2007 Location: La Spezia, Italy Posts: 834	Re: Brand new Philips KT3 with weak CRT No, this one has just a few resistors on the CRT socket board, in the KT3 the video amps are on a plug in card on the main chassis. AFAIK the Philips chassis with the (thick film) output modules on the CRT socket board is the K12

10th Dec 2007, 2:13 am	#6
Maarten Dekatron Join Date: Dec 2007 Location: Haarlem, Netherlands Posts: 4,203	Re: Brand new Philips KT3 with weak CRT It could be 'lazy cathodes'. In that case, things may improve if you let the set play for several hours. I also know of certain TV sets where the tubes were apparently not driven hard enough and the emission of one or more cathodes would be way off after a few years of usage, which could be fixed by applying 12 volt to the heaters for a few minutes.

10th Dec 2007, 8:38 am	#7
Dr-Watts Heptode Join Date: Dec 2006 Location: Milton Keynes, Buckinghamshire, UK. Posts: 696	Re: Brand new Philips KT3 with weak CRT S/C the choke or chokes on the tube base and run it for a day or so, that usually cheers em up Dr. Dave __________________ Do you have the scope to be a TV repair man

10th Dec 2007, 8:52 am	#8
Jimmyhaflinger Heptode Join Date: Feb 2007 Location: La Spezia, Italy Posts: 834	Re: Brand new Philips KT3 with weak CRT I have just swapped the video output card, but the blue is still weak, and i still have the heavy blue smearing around highlights. The smearing gets far worse when the set is warm, after a half hour or so, and no matter how you adjust the bias and drive, you just can't get the CRT to display decent colours At this point i'm starting to realize that this set is still brand new and unused because it had a bad CRT out of the box Francesco

11th Dec 2007, 11:04 am	#10
flyingtech55 Octode Join Date: Nov 2005 Location: Ayrshire, UK. Posts: 1,096	Re: Brand new Philips KT3 with weak CRT Hi Check the A1 voltage. If it's low you get these symptoms because of saturating the RGBs as Maarten says. The thing is, you don't know the history of the set. It may be brand new and the tube was faulty from new, the tube may have deteriorated through non use, the set may have been 'robbed', it may have been a 'hanger queen' or there's nothing fundamentally wrong with the set, it's just been fiddled with so much in the past that it needs to be set properly by the book. However, it is suspicious that it's new in its box and was never sold. HTH TimR

11th Dec 2007, 8:10 pm	#11
Jimmyhaflinger Heptode Join Date: Feb 2007 Location: La Spezia, Italy Posts: 834	Re: Brand new Philips KT3 with weak CRT I have measured a few voltages, I have 163 volts on the RGB output card, (it should be 155) and 400 volts on the G2 With 400 volts on the G2 the picture looks normally bright, but with a lot of blue smearing, if i turn up the G2 voltage to a point just before the flyback lines become visible, the smearing gets better but at this point the picture is ridiculously bright and dull. Francesco

12th Dec 2007, 8:29 am	#12
Jimmyhaflinger Heptode Join Date: Feb 2007 Location: La Spezia, Italy Posts: 834	Re: Brand new Philips KT3 with weak CRT I have left the set on all night with the shorted chokes, this improved the emission of the blue gun and now i have a good greyscale and it no longer takes 20 minutes for the blue to wake up. But... the smearing has got far worse! the blue is now smearing for over an inch and now i have some red smearing too... Francesco

12th Dec 2007, 11:31 am	#13
flyingtech55 Octode Join Date: Nov 2005 Location: Ayrshire, UK. Posts: 1,096	Re: Brand new Philips KT3 with weak CRT Hi Jimmyhaflinger It's beginning to look like the CRT is duff. Are the RGB outputs on the CRT base PCB or are they on the main PCB? TimR

13th Dec 2007, 10:24 pm	#14
Jimmyhaflinger Heptode Join Date: Feb 2007 Location: La Spezia, Italy Posts: 834	Re: Brand new Philips KT3 with weak CRT Well, KT3s as well as Kt4s-K40s are still quite common here, and it's still relatively easy to find them, so i think i'll find a good CRT sooner or later. I think the same CRT was also used in CTX sets too. What's getting really difficult to find are K30 and K35 sets, apparently, most developed weak CRTs and were mass scrapped the late 90s, i used to find tons of them, they rarely had a decent picture, and the few that did usually had gouged screens or busted cabinets I should have kept some of them, but i was mainly interested in K9, K11 and K12 sets back then... now they're all gone and a 1983 "spatial stereo super selection" is one of my top wishes now... Last edited by Jimmyhaflinger; 13th Dec 2007 at 10:30 pm.