1963 TV restoration - Page 3 - UK Vintage Radio Repair and Restoration Discussion Forum

Sideband · 16th Sep 2013, 8:20 pm

You can hear the hum on the sound but on the picture, the hum shows as a ripple or waving.

It's more likely that you can hear the frame transformer humming at 50Hz which is the frame scan frequency. This may happen even when the smoothing cans are replaced.

Rich

Retro-valve-guy · 16th Sep 2013, 9:22 pm

Hum is on speaker,also when I disconnect the speaker there is still hum,I think its coming from the sound trans.,can faulty smoothing caps cause the problems with picture,I mean It does show up,and deflection does work and everything but its just dizzy and not straight as you can see in pics.

Retro-valve-guy · 28th Sep 2013, 3:52 pm

Here with some Updates and results !

After replacing the bad filter cans,I got this...,nice picture with no dark spots,everything seems to be fine, I'm also impressed by the brightness of this old CRT, which is very bright, not much use on it.

The tuner isn't working well it does kind-a.

Everytime I turn the TV on, when the sound comes on ,I can hear the sound of analog snow ,but when the high voltage(flyback) kicks in the tuner stops working, I mean the sound,and then something starts to buzz, I don't think i'ts the speaker, maybe the sound output transformer.

Don't know ?

Retro-valve-guy · 3rd Oct 2013, 6:15 pm

Okay so I made some test.

Whenever I unplug the yoke from the TV (has a safety,so no B+ in the high voltage),the tuner seems to work fine because I can hear the sound from the analogue snow, but as soon as I plug the yoke back in the sound dims down to humming, just as I would have bad filter caps, the tuner does not work properly

Also when I change the frequency for the vertical transformer the buzzing changes to faster and slower.
What's weird is that when there isn't HV, the tuner (sound) works OK,but when HV is active it doesn't.

Help please!

Danny · 4th Oct 2013, 9:22 am

Hi

You have an AGC fault. This type of fault makes my toes curl up.

Danny

Retro-valve-guy · 7th Oct 2013, 8:18 am

I'm getting very frustrated with this TV now. Before I replaced the main smoothing caps, the tuner was working OK, got very nice sound and there was a very low signal on the tube screen and the analogue snow was just slightly visible BUT THE SIGNAL was being delivered to the tube, but now absolutely nothing.

There is either a problem in the IF or RF stage. How can I find the problem now?

The tuner itself is probably OK, because I measured the voltages going to it and they seem normal.

Also I checked the voltage of the plate on the PCL84 and I got about 219 V dc and in the schematics it says that there should be 125V; is that normal?

Danny · 7th Oct 2013, 9:12 am

Hi,

Sorry but I can't see the diagrams very clearly but you need to trace the agc line to the if this will head towards the lopt/flyback transformer.

Once you have found this on the diagram you will have to trace it through on the set.

Check all the caps you have replaced already for mistakes, then check all caps connected to the agc line as I reckon this is where the problem is.

Danny

Retro-valve-guy · 20th Mar 2014, 9:08 pm

Okay back to the thing

I don't get absolutely nothing from the tuner, like its dead, I was checking some of the voltages on the IF stage tubes and they all seem fine, also every time iI poked on of the pins on the tubes there was interference on the speaker so I guess the IF stages are okay the only thing that is suspicious is the tube on the tuner, a PCF 80 and it doesn't get hot like the others do, only the filament is working ,but iI tried multiple PCF80's and still the same thing, it's like the tuner itself is defective, help please!

Everything else works as new, I also replaced every single capacitor in that damn thing.

Retro-valve-guy · 21st Mar 2014, 3:42 pm

Okay so Im getting retrace lines on my screen, which means the tuner IF,video stage has a problem, I think its the AGC, but how can I be certain?

Also on the tuner there should be like -160v and -125v but iI'm getting +240v ?

I also got the full schematic of the thing gonna post it later.

Retro-valve-guy · 21st Mar 2014, 8:52 pm

http://www.elektronik.si/phpBB2/download.php?id=55365

Here is the full schematics for my tv, so can someone tell me where the AGC lines go and where to look for this component?

Any help would be welcomed !

Sideband · 22nd Mar 2014, 9:22 am

A password is needed for that link so not a lot of use!

Rich

Retro-valve-guy · 22nd Mar 2014, 10:32 am

Okay so I fixed it, here is the link for the schematics :

http://www.keepandshare.com/doc18/view.php?id=2130&da=y

Freya · 22nd Mar 2014, 10:54 am

link still needs password

Retro-valve-guy · 22nd Mar 2014, 11:00 am

Okay this one must work !

http://www.keepandshare.com/doc18/21...m-2-0-meg?da=y

matthewhouse · 22nd Mar 2014, 3:07 pm

Still doesn't work!

Sideband · 22nd Mar 2014, 3:50 pm

Nope. It says Bandwidth limit has been exceeded!

Retro-valve-guy · 22nd Mar 2014, 4:49 pm

Finally I managed to zip it,had some problems and did it on a different PC, now it should work.

So can somebody help me trace out the AGC lines, because I have a feeling I have a open circuit resistor or something of that nature ?

16th Sep 2013, 8:20 pm	#41
Sideband Dekatron Join Date: Oct 2003 Location: Croydon, Surrey, UK. Posts: 7,571	Re: 1963 TV restoration You can hear the hum on the sound but on the picture, the hum shows as a ripple or waving. It's more likely that you can hear the frame transformer humming at 50Hz which is the frame scan frequency. This may happen even when the smoothing cans are replaced. Rich __________________ There are lots of brilliant keyboard players and then there is Rick Wakeman.....

16th Sep 2013, 9:22 pm	#42
Retro-valve-guy Retired Dormant Member Join Date: Aug 2013 Location: Celje, Slovenia. Posts: 128	Re: 1963 TV restoration Hum is on speaker,also when I disconnect the speaker there is still hum,I think its coming from the sound trans.,can faulty smoothing caps cause the problems with picture,I mean It does show up,and deflection does work and everything but its just dizzy and not straight as you can see in pics.

28th Sep 2013, 3:52 pm	#43
Retro-valve-guy Retired Dormant Member Join Date: Aug 2013 Location: Celje, Slovenia. Posts: 128	Re: 1963 TV restoration Here with some Updates and results ! After replacing the bad filter cans,I got this...,nice picture with no dark spots,everything seems to be fine, I'm also impressed by the brightness of this old CRT, which is very bright, not much use on it. The tuner isn't working well it does kind-a. Everytime I turn the TV on, when the sound comes on ,I can hear the sound of analog snow ,but when the high voltage(flyback) kicks in the tuner stops working, I mean the sound,and then something starts to buzz, I don't think i'ts the speaker, maybe the sound output transformer. Don't know ? Attached Thumbnails

3rd Oct 2013, 6:15 pm	#44
Retro-valve-guy Retired Dormant Member Join Date: Aug 2013 Location: Celje, Slovenia. Posts: 128	Re: 1963 TV restoration Okay so I made some test. Whenever I unplug the yoke from the TV (has a safety,so no B+ in the high voltage),the tuner seems to work fine because I can hear the sound from the analogue snow, but as soon as I plug the yoke back in the sound dims down to humming, just as I would have bad filter caps, the tuner does not work properly Also when I change the frequency for the vertical transformer the buzzing changes to faster and slower. What's weird is that when there isn't HV, the tuner (sound) works OK,but when HV is active it doesn't. Help please!

4th Oct 2013, 9:22 am	#45
Danny Heptode Join Date: Jul 2003 Location: North Walsham, Norfolk, UK. Posts: 516	Re: 1963 TV restoration Hi You have an AGC fault. This type of fault makes my toes curl up. Danny

7th Oct 2013, 8:18 am	#46
Retro-valve-guy Retired Dormant Member Join Date: Aug 2013 Location: Celje, Slovenia. Posts: 128	Re: 1963 TV restoration I'm getting very frustrated with this TV now. Before I replaced the main smoothing caps, the tuner was working OK, got very nice sound and there was a very low signal on the tube screen and the analogue snow was just slightly visible BUT THE SIGNAL was being delivered to the tube, but now absolutely nothing. There is either a problem in the IF or RF stage. How can I find the problem now? The tuner itself is probably OK, because I measured the voltages going to it and they seem normal. Also I checked the voltage of the plate on the PCL84 and I got about 219 V dc and in the schematics it says that there should be 125V; is that normal?

7th Oct 2013, 9:12 am	#47
Danny Heptode Join Date: Jul 2003 Location: North Walsham, Norfolk, UK. Posts: 516	Re: 1963 TV restoration Hi, Sorry but I can't see the diagrams very clearly but you need to trace the agc line to the if this will head towards the lopt/flyback transformer. Once you have found this on the diagram you will have to trace it through on the set. Check all the caps you have replaced already for mistakes, then check all caps connected to the agc line as I reckon this is where the problem is. Danny

20th Mar 2014, 9:08 pm	#48
Retro-valve-guy Retired Dormant Member Join Date: Aug 2013 Location: Celje, Slovenia. Posts: 128	Re: 1963 TV restoration Okay back to the thing I don't get absolutely nothing from the tuner, like its dead, I was checking some of the voltages on the IF stage tubes and they all seem fine, also every time iI poked on of the pins on the tubes there was interference on the speaker so I guess the IF stages are okay the only thing that is suspicious is the tube on the tuner, a PCF 80 and it doesn't get hot like the others do, only the filament is working ,but iI tried multiple PCF80's and still the same thing, it's like the tuner itself is defective, help please! Everything else works as new, I also replaced every single capacitor in that damn thing.

21st Mar 2014, 3:42 pm	#49
Retro-valve-guy Retired Dormant Member Join Date: Aug 2013 Location: Celje, Slovenia. Posts: 128	Re: 1963 TV restoration Okay so Im getting retrace lines on my screen, which means the tuner IF,video stage has a problem, I think its the AGC, but how can I be certain? Also on the tuner there should be like -160v and -125v but iI'm getting +240v ? I also got the full schematic of the thing gonna post it later. Attached Thumbnails

21st Mar 2014, 8:52 pm	#50
Retro-valve-guy Retired Dormant Member Join Date: Aug 2013 Location: Celje, Slovenia. Posts: 128	Re: 1963 TV restoration http://www.elektronik.si/phpBB2/download.php?id=55365 Here is the full schematics for my tv, so can someone tell me where the AGC lines go and where to look for this component? Any help would be welcomed !

22nd Mar 2014, 9:22 am	#51
Sideband Dekatron Join Date: Oct 2003 Location: Croydon, Surrey, UK. Posts: 7,571	Re: 1963 TV restoration A password is needed for that link so not a lot of use! Rich __________________ There are lots of brilliant keyboard players and then there is Rick Wakeman.....

22nd Mar 2014, 10:32 am	#52
Retro-valve-guy Retired Dormant Member Join Date: Aug 2013 Location: Celje, Slovenia. Posts: 128	Re: 1963 TV restoration Okay so I fixed it, here is the link for the schematics : http://www.keepandshare.com/doc18/view.php?id=2130&da=y Last edited by Retro-valve-guy; 22nd Mar 2014 at 10:38 am. Reason: mistake

22nd Mar 2014, 10:54 am	#53
Freya Octode Join Date: Jan 2009 Location: Falmouth, Cornwall, UK. Posts: 1,989	Re: 1963 TV restoration link still needs password __________________ Stephen _________"It`s only an old telly" ___

22nd Mar 2014, 11:00 am	#54
Retro-valve-guy Retired Dormant Member Join Date: Aug 2013 Location: Celje, Slovenia. Posts: 128	Re: 1963 TV restoration Okay this one must work ! http://www.keepandshare.com/doc18/21...m-2-0-meg?da=y

22nd Mar 2014, 3:07 pm	#55
matthewhouse Octode Join Date: Jul 2006 Location: Willand, Devon, UK. Posts: 1,023	Re: 1963 TV restoration Still doesn't work!

22nd Mar 2014, 3:50 pm	#56
Sideband Dekatron Join Date: Oct 2003 Location: Croydon, Surrey, UK. Posts: 7,571	Re: 1963 TV restoration Nope. It says Bandwidth limit has been exceeded! __________________ There are lots of brilliant keyboard players and then there is Rick Wakeman.....