Philips 26CS3471 - K35 chassis - UK Vintage Radio Repair and Restoration Discussion Forum

boo1000 · 29th Aug 2011, 10:34 pm

Hi there!
This is my first post here, mu name is Lorenzo, I'm 25 and I live in Tuscany. I want to thank you all for all the incredibly useful infos I've found here reading the previous posts.
So, let's go straight to the problem:
My recently acquired Philips sometimes loses the sync, with the picture rolling quickly, as you can see in the attached photo. I changed the electrolytics in the SYNC board, but nothing changed. Any idea is welcomed. Thank you very much!
Cheers.
Lorenzo

tri-comp · 30th Aug 2011, 7:57 am

Hi Lorenzo and welcome to the forum,

Do you have access to an oscilloscope?
If yes, check the vertical saw-tooth pulse leaving U12 on pin-2. It's suppose to be 4Vpp.
Check also pin-3 where you should see the same return-pulse from the output circuit; also 4Vpp.
If you already replaced all electrolytic cap's on U12 there isn't much chance of finding the fault there, except for the periodic failing of TDA3571Q and the odd chance of R390 being unstable.
So, I would continue replacing electrolytics in the Frame output like C522, C542, C510, C531 and maybe even the output cap. C521 when you are at it.

rgds,

/tri-comp

dominicbeesley · 30th Aug 2011, 10:41 am

Hello Lorenzo,

Are you running that TV from a digital set top box, that looks more like a fault with the box rather than the TV as the pixture is chopped up into little pieces rather than normal sized pictures one on top of the other. Have you another box to try with?

Dom

boo1000 · 30th Aug 2011, 1:14 pm

Hi Dominic,

the problem is the same even with the good old analogue (we have still the PAL system in this part of Italy, until next year), so is something dealing with the set...

boo1000 · 30th Aug 2011, 11:37 pm

I changed the suggested electrolytics, but nothing changed. Sometimes the set starts normally, and goes on for some time, like half an hour. Then, suddenly, it starts losing sync: at first the picture rolls only during the channel change, then it starts to roll faster and finally it becomes like the picture I attached. If you switch off and then switch on the set, the problem persists.
I haven't got a scope, so it's a little bit difficult...

John123 · 31st Aug 2011, 11:33 pm

I found a fault listed for the Philips K30, but I don't know how similar the design is in comparison to the K35:

Sync - loss of line hold: C7341 (0.0012uf) s/c.

Amraduk · 1st Sep 2011, 12:55 am

Quote:

Originally Posted by John123

Sync - loss of line hold: C7341 (0.0012uf) s/c.

That's not really relevant, because it's the field that isn't locked!

Regards,

Dave.

boo1000 · 1st Sep 2011, 2:16 pm

Moreover, it's a bit different... I haven't got a C7341...

boo1000 · 2nd Sep 2011, 12:53 pm

Update:

Today's situation,
Nothing, with the frame very compressed. It's not so blue, actually, it must be the photo.
Any idea?

Thanks!

peterradio · 2nd Sep 2011, 6:48 pm

I would change all the electrolitic caps in the PSU 1st as ripple on the ht & lt lins can cuase havoc on the chassis

boo1000 · 3rd Sep 2011, 1:03 pm

This is the voltage between R531 and R532, at the output of the vertical stage.
It's low (it is about 15Vpp, and it should be 25) and it's affected by ripple... I'll change the electrolytics and perhaps the transistors of the vertical stage... What do you think?

boo1000 · 18th Oct 2011, 2:29 pm

UPDATE!

The fault was a transistor in the SYNC module. Now the deflection is very good. Excellent tube, too! So, next problem: the tuning doesn't work anymore. It can't find any channel. The channel number goes up and down correctly, but it doesn't work. Sometimes it's snow with some noise, sometimes it's blank screen. From SCART no problem, although the volume control has a strange behaviour: when pushing VOL+, it starts very very quiet and then the level rises up suddenly. Such a strange control, not gradual at all. I think it's something about the logic board. It uses a TRD4 logic, do you have any experience on it?
Thank you, guys. Your help is much appreciated.
Lorenzo

29th Aug 2011, 10:34 pm	#1
boo1000 Retired Dormant Member Join Date: Aug 2010 Location: Pontedera, Pisa, Italy Posts: 28	Philips 26CS3471 - K35 chassis Hi there! This is my first post here, mu name is Lorenzo, I'm 25 and I live in Tuscany. I want to thank you all for all the incredibly useful infos I've found here reading the previous posts. So, let's go straight to the problem: My recently acquired Philips sometimes loses the sync, with the picture rolling quickly, as you can see in the attached photo. I changed the electrolytics in the SYNC board, but nothing changed. Any idea is welcomed. Thank you very much! Cheers. Lorenzo Attached Thumbnails

30th Aug 2011, 7:57 am	#2
tri-comp Heptode Join Date: Oct 2008 Location: Aalborg, Denmark Posts: 903	Re: Philips 26CS3471 - K35 chassis Hi Lorenzo and welcome to the forum, Do you have access to an oscilloscope? If yes, check the vertical saw-tooth pulse leaving U12 on pin-2. It's suppose to be 4Vpp. Check also pin-3 where you should see the same return-pulse from the output circuit; also 4Vpp. If you already replaced all electrolytic cap's on U12 there isn't much chance of finding the fault there, except for the periodic failing of TDA3571Q and the odd chance of R390 being unstable. So, I would continue replacing electrolytics in the Frame output like C522, C542, C510, C531 and maybe even the output cap. C521 when you are at it. rgds, /tri-comp

30th Aug 2011, 10:41 am	#3
dominicbeesley Octode Join Date: Nov 2004 Location: Hebden Bridge, West Yorkshire, UK. Posts: 1,885	Re: Philips 26CS3471 - K35 chassis Hello Lorenzo, Are you running that TV from a digital set top box, that looks more like a fault with the box rather than the TV as the pixture is chopped up into little pieces rather than normal sized pictures one on top of the other. Have you another box to try with? Dom

30th Aug 2011, 1:14 pm	#4
boo1000 Retired Dormant Member Join Date: Aug 2010 Location: Pontedera, Pisa, Italy Posts: 28	Re: Philips 26CS3471 - K35 chassis Hi Dominic, the problem is the same even with the good old analogue (we have still the PAL system in this part of Italy, until next year), so is something dealing with the set...

30th Aug 2011, 11:37 pm	#5
boo1000 Retired Dormant Member Join Date: Aug 2010 Location: Pontedera, Pisa, Italy Posts: 28	Re: Philips 26CS3471 - K35 chassis I changed the suggested electrolytics, but nothing changed. Sometimes the set starts normally, and goes on for some time, like half an hour. Then, suddenly, it starts losing sync: at first the picture rolls only during the channel change, then it starts to roll faster and finally it becomes like the picture I attached. If you switch off and then switch on the set, the problem persists. I haven't got a scope, so it's a little bit difficult...

31st Aug 2011, 11:33 pm	#6
John123 Heptode Join Date: Jan 2007 Location: Luton, Bedfordshire, UK. Posts: 891	Re: Philips 26CS3471 - K35 chassis I found a fault listed for the Philips K30, but I don't know how similar the design is in comparison to the K35: Sync - loss of line hold: C7341 (0.0012uf) s/c. __________________ Regards, John

1st Sep 2011, 2:16 pm	#8
boo1000 Retired Dormant Member Join Date: Aug 2010 Location: Pontedera, Pisa, Italy Posts: 28	Re: Philips 26CS3471 - K35 chassis Moreover, it's a bit different... I haven't got a C7341...

2nd Sep 2011, 12:53 pm	#9
boo1000 Retired Dormant Member Join Date: Aug 2010 Location: Pontedera, Pisa, Italy Posts: 28	Re: Philips 26CS3471 - K35 chassis Update: Today's situation, Nothing, with the frame very compressed. It's not so blue, actually, it must be the photo. Any idea? Thanks! Attached Thumbnails

2nd Sep 2011, 6:48 pm	#10
peterradio Retired Dormant Member Join Date: Jun 2011 Location: Dartford, Kent Posts: 9	Re: Philips 26CS3471 - K35 chassis I would change all the electrolitic caps in the PSU 1st as ripple on the ht & lt lins can cuase havoc on the chassis

3rd Sep 2011, 1:03 pm	#11
boo1000 Retired Dormant Member Join Date: Aug 2010 Location: Pontedera, Pisa, Italy Posts: 28	Re: Philips 26CS3471 - K35 chassis This is the voltage between R531 and R532, at the output of the vertical stage. It's low (it is about 15Vpp, and it should be 25) and it's affected by ripple... I'll change the electrolytics and perhaps the transistors of the vertical stage... What do you think? Attached Thumbnails

18th Oct 2011, 2:29 pm	#12
boo1000 Retired Dormant Member Join Date: Aug 2010 Location: Pontedera, Pisa, Italy Posts: 28	Re: Philips 26CS3471 - K35 chassis UPDATE! The fault was a transistor in the SYNC module. Now the deflection is very good. Excellent tube, too! So, next problem: the tuning doesn't work anymore. It can't find any channel. The channel number goes up and down correctly, but it doesn't work. Sometimes it's snow with some noise, sometimes it's blank screen. From SCART no problem, although the volume control has a strange behaviour: when pushing VOL+, it starts very very quiet and then the level rises up suddenly. Such a strange control, not gradual at all. I think it's something about the logic board. It uses a TRD4 logic, do you have any experience on it? Thank you, guys. Your help is much appreciated. Lorenzo