UK Vintage Radio Repair and Restoration Powered By Google Custom Search Vintage Radio and TV Service Data

Go Back   UK Vintage Radio Repair and Restoration Discussion Forum > Specific Vintage Equipment > Vintage Television and Video

Notices

Vintage Television and Video Vintage television and video equipment, programmes, VCRs etc.

Closed Thread
 
Thread Tools
Old 23rd Sep 2022, 11:28 pm   #21
Michael Maurice
Moderator
 
Michael Maurice's Avatar
 
Join Date: Feb 2006
Location: Wembley, Middlesex
Posts: 7,219
Default Re: AGA black and white TV

An update: Most of the miniprint capacitors (RIFA) have been replaced especially in the line, frame and audio stages.

I now have pictures and sound but:

I did have some frame bounce, adjusting the controls seemed to clear that.

i had it on for quite a few hours when the 2K2 ohm resistor between the anode of the PY88 and the G2 of the PL504 sprung open (no picture)

I resoldered it and go a full picture but an hour or so later it sprung open again.
I'm wondering what to do. Do I need to use special solder?
__________________
Forum Moderator

http://www.michaelmauricerepairs.co.uk/
Michael Maurice is offline  
Old 24th Sep 2022, 8:03 am   #22
Nuvistor
Dekatron
 
Nuvistor's Avatar
 
Join Date: Aug 2013
Location: Wigan, Greater Manchester, UK.
Posts: 9,427
Default Re: AGA black and white TV

Check the cathode current of the PL504 is within specifications.
In some of these fusible resistors high melting point solder was specified.
__________________
Frank
Nuvistor is offline  
Old 24th Sep 2022, 2:56 pm   #23
Michael Maurice
Moderator
 
Michael Maurice's Avatar
 
Join Date: Feb 2006
Location: Wembley, Middlesex
Posts: 7,219
Default Re: AGA black and white TV

The cathode is grounded so cant check the current, where would I get HMP solder or would I be best to bypass the fuse bit altogether?
__________________
Forum Moderator

http://www.michaelmauricerepairs.co.uk/
Michael Maurice is offline  
Old 30th Sep 2022, 12:40 pm   #24
Michael Maurice
Moderator
 
Michael Maurice's Avatar
 
Join Date: Feb 2006
Location: Wembley, Middlesex
Posts: 7,219
Default Re: AGA black and white TV

I have obtained some HMP solder and resoldered the resistor.

The set is running and I’m testing it as we speak
__________________
Forum Moderator

http://www.michaelmauricerepairs.co.uk/
Michael Maurice is offline  
Old 30th Sep 2022, 12:52 pm   #25
Nuvistor
Dekatron
 
Nuvistor's Avatar
 
Join Date: Aug 2013
Location: Wigan, Greater Manchester, UK.
Posts: 9,427
Default Re: AGA black and white TV

I don’t recommend bypassing the fuse, if it still fails make sure there was no standard solder in the joint before using HMP.
You could put a 1 ohm resistor in the cathode circuit and measure the voltage drop to check the PL504 current.
It’s 40 odd years since I dealt with TV’s , other may have more advice.
__________________
Frank
Nuvistor is offline  
Old 30th Sep 2022, 1:24 pm   #26
Michael Maurice
Moderator
 
Michael Maurice's Avatar
 
Join Date: Feb 2006
Location: Wembley, Middlesex
Posts: 7,219
Default Re: AGA black and white TV

I removed the resistor from the board, removed the solder, and resoldered the resistor using the new HMP.

I haven't bypassed anything.
__________________
Forum Moderator

http://www.michaelmauricerepairs.co.uk/
Michael Maurice is offline  
Old 30th Sep 2022, 8:33 pm   #27
Nuvistor
Dekatron
 
Nuvistor's Avatar
 
Join Date: Aug 2013
Location: Wigan, Greater Manchester, UK.
Posts: 9,427
Default Re: AGA black and white TV

Hopefully fixed.
__________________
Frank
Nuvistor is offline  
Old 1st Oct 2022, 9:03 am   #28
Michael Maurice
Moderator
 
Michael Maurice's Avatar
 
Join Date: Feb 2006
Location: Wembley, Middlesex
Posts: 7,219
Default Re: AGA black and white TV

That part of it is fixed, it was running for quite a long time, but there are one or two other problems.

Every so often there is frame bounce and sometimes the picture slips vertically so you have the blanking strip in the middle of the screen.

I will post up diagrams possibly asap. It seems probable that the cause is around the ECH84 sync separator.
__________________
Forum Moderator

http://www.michaelmauricerepairs.co.uk/
Michael Maurice is offline  
Old 1st Oct 2022, 9:42 am   #29
Nuvistor
Dekatron
 
Nuvistor's Avatar
 
Join Date: Aug 2013
Location: Wigan, Greater Manchester, UK.
Posts: 9,427
Default Re: AGA black and white TV

The ECH84 may be a noise cancelling sync separator, not often seen in UK sets due to the 625 line Negative modulation transmissions on UHF. The noise cancellation was more important on VHF were noise spikes could affect sync, whereas with the UK 405 line positive modulation VHF system they caused white dots on the picture.

https://worldradiohistory.com/hd2/ID...-Page-0002.pdf
__________________
Frank
Nuvistor is offline  
Old 27th Oct 2022, 10:33 am   #30
Michael Maurice
Moderator
 
Michael Maurice's Avatar
 
Join Date: Feb 2006
Location: Wembley, Middlesex
Posts: 7,219
Default Re: AGA black and white TV

An update: I replaced a couple of 220K resistors around the ECH84 together with the valve holder itself and I've now got a very good picture.

However for some reason I've got no sound.
__________________
Forum Moderator

http://www.michaelmauricerepairs.co.uk/
Michael Maurice is offline  
Old 27th Oct 2022, 10:35 am   #31
Michael Maurice
Moderator
 
Michael Maurice's Avatar
 
Join Date: Feb 2006
Location: Wembley, Middlesex
Posts: 7,219
Default Re: AGA black and white TV

Here are some diagrams.
Attached Thumbnails
Click image for larger version

Name:	Frame and Line OP stage.jpg
Views:	39
Size:	108.6 KB
ID:	266930   Click image for larger version

Name:	line op stage.jpg
Views:	36
Size:	86.0 KB
ID:	266931   Click image for larger version

Name:	VHF IF Sync.jpg
Views:	33
Size:	50.4 KB
ID:	266932   Click image for larger version

Name:	6.jpg
Views:	36
Size:	100.7 KB
ID:	266933  
__________________
Forum Moderator

http://www.michaelmauricerepairs.co.uk/
Michael Maurice is offline  
Old 27th Oct 2022, 10:45 am   #32
Roger Ramjet
Heptode
 
Join Date: Feb 2022
Location: Leicestershire, UK.
Posts: 690
Default Re: AGA black and white TV

Quote:
Originally Posted by Michael Maurice View Post
There is snow, very faint snow, you can see it by turning the contrast up, the brightness down a bit and changing channels. It does have a 240V setting so I'll make sure its set for that.
UK mains has long since been harmonised with Europe at 220V. Might pay though to confirm with meter as I have often measured 230V.

Rog
Roger Ramjet is offline  
Old 27th Oct 2022, 11:08 am   #33
Jac
Heptode
 
Jac's Avatar
 
Join Date: Jun 2006
Location: Eindhoven, Netherlands.
Posts: 640
Default Re: AGA black and white TV

Quote:
Originally Posted by Roger Ramjet View Post
UK mains has long since been harmonised with Europe at 220V. Might pay though to confirm with meter as I have often measured 230V.

Rog
Europe Continent is 230V.

Jac
Jac is offline  
Old 27th Oct 2022, 12:18 pm   #34
Nuvistor
Dekatron
 
Nuvistor's Avatar
 
Join Date: Aug 2013
Location: Wigan, Greater Manchester, UK.
Posts: 9,427
Default Re: AGA black and white TV

What signal are you feeding the TV, this set uses 5.5Mhz inter carrier sound according to that circuit not 6Mhz as in the UK 625 signal?

I thought the UK voltage was harmonised to 230volts.
__________________
Frank
Nuvistor is offline  
Old 28th Oct 2022, 3:05 pm   #35
Michael Maurice
Moderator
 
Michael Maurice's Avatar
 
Join Date: Feb 2006
Location: Wembley, Middlesex
Posts: 7,219
Default Re: AGA black and white TV

The reason for no sound was a broken wire between the O/P TX and the connection tag strip. I soldered the speaker wires direct to the o/p transformer and that solved that!

The TV was working fine until I replaced the back. No after some time the picture goes darker and darker.

One thing I noticed is that when the picture is dark, when you switch the set off you get a bright spot in the middle.

Any ideas?
__________________
Forum Moderator

http://www.michaelmauricerepairs.co.uk/
Michael Maurice is offline  
Old 28th Oct 2022, 11:00 pm   #36
Nuvistor
Dekatron
 
Nuvistor's Avatar
 
Join Date: Aug 2013
Location: Wigan, Greater Manchester, UK.
Posts: 9,427
Default Re: AGA black and white TV

Measure the voltages on the crt base, they should change when it it goes darker. Trace the one that’s changing.
OK on the sound fault, I didn’t realise it had been changed to work on the UK system.
__________________
Frank
Nuvistor is offline  
Old 29th Oct 2022, 10:05 am   #37
Cobaltblue
Moderator
 
Cobaltblue's Avatar
 
Join Date: Dec 2010
Location: Exeter, Devon and Poole, Dorset UK.
Posts: 6,823
Default Re: AGA black and white TV

Quote:
Originally Posted by Roger Ramjet View Post
Quote:
Originally Posted by Michael Maurice View Post
There is snow, very faint snow, you can see it by turning the contrast up, the brightness down a bit and changing channels. It does have a 240V setting so I'll make sure its set for that.

UK mains has long since been harmonised with Europe at 220V. Might pay though to confirm with meter as I have often measured 230V.

Rog
Not wishing to derail this thread but its important to know what the supplies really are, inexperienced people read these posts.

UK mains voltage was "harmonised" at 230V but in reality it did not change from 240V just the way it is specified.

Some parts of the UK still have a nominal 250V supply.

230 volts -6%, +10%. This gives an allowed voltage range of 216.2 volts to 253.0 volts.

ISTR that before harmonisation the supply was specified as 240V ±10% and indeed we still test our equipment to that upper limit of 264V (actually we use 205V to 268V).

Modern equipment will tends to be able to accept 230V +/-10% i.e. 207-253V.

At my home we are just 50M (as the cable runs) from a sub station and my mains is usually in the range 245 to 248V.

Over time as new infrastructure gets replaced I guess the substations will be set for a nominal 230V.

Cheers

Mike T
__________________
Invisible airwaves crackle with life or at least they used to
Mike T BVWS member.
www.cossor.co.uk
Cobaltblue is offline  
Old 29th Oct 2022, 10:06 am   #38
Radio Wrangler
Moderator
 
Radio Wrangler's Avatar
 
Join Date: Mar 2012
Location: Fife, Scotland, UK.
Posts: 22,801
Default Re: AGA black and white TV

Quote:
Originally Posted by Roger Ramjet View Post
Quote:
Originally Posted by Michael Maurice View Post
There is snow, very faint snow, you can see it by turning the contrast up, the brightness down a bit and changing channels. It does have a 240V setting so I'll make sure its set for that.
UK mains has long since been harmonised with Europe at 220V. Might pay though to confirm with meter as I have often measured 230V.

Rog
Europe and the UK have been harmonised on 230V

BUT, the tolerance has been engineered so that both the UK's old 240V (with its old tolerance) and the European mainland's 230V (With its old tolerance) fit within the new tolerance bounds.

So expect 240V from a socket in the UK. The wording has changed, the voltage hasn't. New appliances get 230 written on them but are required to work over a wide enough range to encompass the difference.

David
__________________
Can't afford the volcanic island yet, but the plans for my monorail and the goons' uniforms are done
Radio Wrangler is offline  
Old 5th Nov 2022, 12:27 am   #39
Michael Maurice
Moderator
 
Michael Maurice's Avatar
 
Join Date: Feb 2006
Location: Wembley, Middlesex
Posts: 7,219
Default Re: AGA black and white TV

An update: I replaced three high value resistors a 470K and two 680K resistors in the line o/p stage which go directly to the CRT grids.

Upon switching on I was rewarded with a very bright picture which gave a normal picture with the brightness turned down.

I then fitted the back cover, turned the heating on and left it on. So far so good, its been on for around 6-7 hours.
__________________
Forum Moderator

http://www.michaelmauricerepairs.co.uk/
Michael Maurice is offline  
Old 5th Nov 2022, 10:51 am   #40
Nuvistor
Dekatron
 
Nuvistor's Avatar
 
Join Date: Aug 2013
Location: Wigan, Greater Manchester, UK.
Posts: 9,427
Default Re: AGA black and white TV

__________________
Frank
Nuvistor is offline  
Closed Thread

Thread Tools



All times are GMT +1. The time now is 2:11 am.


All information and advice on this forum is subject to the WARNING AND DISCLAIMER located at https://www.vintage-radio.net/rules.html.
Failure to heed this warning may result in death or serious injury to yourself and/or others.


Powered by vBulletin®
Copyright ©2000 - 2024, vBulletin Solutions, Inc.
Copyright ©2002 - 2023, Paul Stenning.