Oh no - another V4! - Page 6 - UK Vintage Radio Repair and Restoration Discussion Forum

dominicbeesley · 24th May 2010, 11:08 am

Thanks Frank, I remember your homemade lopt...it's one of the things I keep meaning to give a try out when I next make a telly.

So, what to do?

Remove the perspex bit - this looks tricky but not impossible...

Will cooking this break it up like Chris's? I've been looking at the construction and don't know how you'd get a short to the core as the wires all look to be well away from it unless the core has been "turned" round when the pitch was soft?

I was also going to cook the linearity and width coils.

At what temperature does the wire enamel usually melt?

I'd like to start this afternoon if possible - while Stacey's not here to see me get the entire kitchen, bathroom, carpet, car and next door's cat covered in black pitch!

Any help...please! I'm now way out of my depth!

Cheers

Dom

oldticktock · 24th May 2010, 11:34 am

Hi Dom,

I would wait for Trevor to pop up and advise, as he's specifically done the V4 LOPT heat treatment a few times, I would hate it to end the same way for you.

I still do not fully understand where mine went wrong, It was a total of 2x 2 hour sessions and the pitch on the LOPT never dripped off in great quantities it really only got a bit tacky and shiny, its all intact nothing missing. The width and linearity coils were also getting the heat as a by product of the heating, some of the wax paper dried and peeled off the width coil.

Im quite surprised to be honest considering I was using the least aggressive of the three options for heating.

Chris

murphyv310 · 24th May 2010, 2:05 pm

I am surprised you had problems! I have lost most of the pitch off one I did and it didn't distroy the trannie!
I would make sure that it IS the trannie first, the width and linearity coils could be the culprit you know.
I know you didn't want to disturb the lopt and left it in but in reality its better out of the set.
I still would remove ALL the external connections from the transformer execpt for the EHT lead and check each connection on the transformer to the transformer metalwork on ohms for shorts or leaks, If nothing look elsewhere.

OOOOP's posted this on the wrong V4 thread

dominicbeesley · 24th May 2010, 2:53 pm

Any advice for me Trevor? I've removed the LOPT and if no contrary advice in the next hour I'm going to remove the perspex top if possible and bake it!

Dom

murphyv310 · 24th May 2010, 3:15 pm

At 75C it should be fine I did one at 100c and there was a little distortion, give it a little prod when up to 70c and make sure its not getting soft.

dominicbeesley · 24th May 2010, 4:34 pm

Righto tis in the oven - Will give it until six o'clock with frequeny checks at 60 degrees the pitch is soft an all looks well!

Not sure which way up to stand it while it cooks...

Dom

Heatercathodeshort · 24th May 2010, 7:55 pm

You may as well bung a few spuds round it at the same time. Seems a pity to waste all that good oven heat on an old LOPT.

J.

dominicbeesley · 24th May 2010, 8:22 pm

You might be kidding but I'm going to put in the rest of the roast beef, Yorkshire puds and spuds we had last night to warm up in a minute while the footballs on....

Dom

dominicbeesley · 24th May 2010, 10:39 pm

Well it's had six hours and it's still bubbling!

The perspex has warped a little but still useable.

I'll leave it overnight and give it a few hours tomorrow morning.

On the downside it made my spuds taste a bit funny!

Dom

Alistair D · 24th May 2010, 10:43 pm

Who would have thought that an oven thermometer would become a piece of test equipment!!!.

Joking aside, does anyone know the temperature range of a domestic electric oven?

Al

FRANK.C · 24th May 2010, 11:41 pm

Hi Al
Temperature range of electric oven is usually 35C (as a keep warm function) to 250C.

Frank

dominicbeesley · 25th May 2010, 1:36 pm

Well its now had nine hours at over 100degrees and it's still making a ticking noise when I take it out. Is it really still farting out steam?

What should I do? It's starting to look very lopsided now - the paxolin sides set at a funny angle and the perspex corona ring holders are quite bent?

Dom

murphyv310 · 25th May 2010, 2:16 pm

Hi
Stop, I only gave mine about 2 to 3 hours, natural heat will do the rest, hope its all ok.
Check it against the readings on OTT's thread.
good luck

dominicbeesley · 25th May 2010, 6:00 pm

To quote Roy Walker: "It's good! But it's not quite right!"

Wiring the LOPT back up was a good hour's worth of finger burning fun - switched on and after a bit of twiddling got an .....almost full width picture!

EHT is up a bit at just over 10kV (my AVO8 seems to have lost its magnetism so this is an estimate) had to reset all the centring magnets and the frame amplitude and linearity.

Focus is a tad sharper and doesn't need to be all the way over. But width is still quite low. I've got to go out now but will try and get measurements from the line drive area again. I really can't think what it will be now other than a problem with the scan coils...

Cheers

Dom

Heatercathodeshort · 25th May 2010, 6:08 pm

Yes Stop and leave it a while to settle. The incredible bubbling, smoke, melted tar, burnt fingers, smells, fumes and frustration when replacing a Pye V4 line output transformer has to be experienced to be believed. Definitely has a 'slaughter house' feeling about it..J.

dominicbeesley · 26th May 2010, 12:26 am

Hee Hee, is fun though - unlike abatoir work...

Any ideas what to check next?

Dom

murphyv310 · 26th May 2010, 8:46 am

Hi.
I've known the width and lin coils to have shorted turns, sometimes they look quite cooked! What does it do with the drive trimmer now?

dominicbeesley · 26th May 2010, 12:53 pm

Thanks Trevor,

I didn't get a chance to turn the chassis over last night before I had to go out. Will retry all the drive bits tonight.

Is there a test I can do on the width and lin. controls? It would be good to just know what their resistance, or even better inductance was supposed to be! Is it worth measuring their Q?

The width coil was a mass of goo hard to tell whether it was fromt he enamel or the tape. I replaced the tape anyway as there was a risk of a short between the leadout wires.

Dom

dominicbeesley · 26th May 2010, 6:07 pm

Hi Lads,

Had a spare twenty minutes so went down, resoldered the EHT lead and put the cage back on.

Twiddling the line drive trimmer C101 gave the following results...

All the way out as pictured below: bright with more EHT (had to readjust height controls) and sharp pictures and full width but wobbly verticals

Mid way: dimmer narrower picture - no sign of "kink", less wobbly verticals still a reasonable picture

All way in: very weak looking EHT line wouldn't lock, dim picture at about 3/5 width

No sign of any kink and these all tried with C99 subbed by a 100pF cap.

This all with width control turned fully up (i.e. iron core all the way in).

What to check next? Or should I just leave it!? I'd really like to get this running 100% though - including the width control near the middle!

How to check the width control coil or should I just rewind it!?

Cheers

Dom

Steve_P · 26th May 2010, 7:28 pm

Is the power supply OK at all levels. If not it could cause this sort of thing. C103 if not already changed.

Cheers,

Steve P.

24th May 2010, 11:08 am	#101
dominicbeesley Octode Join Date: Nov 2004 Location: Hebden Bridge, West Yorkshire, UK. Posts: 1,885	Re: Oh no - another V4! Thanks Frank, I remember your homemade lopt...it's one of the things I keep meaning to give a try out when I next make a telly. So, what to do? Remove the perspex bit - this looks tricky but not impossible... Will cooking this break it up like Chris's? I've been looking at the construction and don't know how you'd get a short to the core as the wires all look to be well away from it unless the core has been "turned" round when the pitch was soft? I was also going to cook the linearity and width coils. At what temperature does the wire enamel usually melt? I'd like to start this afternoon if possible - while Stacey's not here to see me get the entire kitchen, bathroom, carpet, car and next door's cat covered in black pitch! Any help...please! I'm now way out of my depth! Cheers Dom

24th May 2010, 11:34 am	#102
oldticktock Retired Dormant Member Join Date: Nov 2009 Location: Weardale, UK. Posts: 1,981	Re: Oh no - another V4! Hi Dom, I would wait for Trevor to pop up and advise, as he's specifically done the V4 LOPT heat treatment a few times, I would hate it to end the same way for you. I still do not fully understand where mine went wrong, It was a total of 2x 2 hour sessions and the pitch on the LOPT never dripped off in great quantities it really only got a bit tacky and shiny, its all intact nothing missing. The width and linearity coils were also getting the heat as a by product of the heating, some of the wax paper dried and peeled off the width coil. Im quite surprised to be honest considering I was using the least aggressive of the three options for heating. Chris Last edited by oldticktock; 24th May 2010 at 11:41 am.

24th May 2010, 2:05 pm	#103
murphyv310 Dekatron Join Date: Sep 2006 Location: Kilmarnock, Ayrshire, UK. Posts: 5,422	Re: Oh no - another V4! I am surprised you had problems! I have lost most of the pitch off one I did and it didn't distroy the trannie! I would make sure that it IS the trannie first, the width and linearity coils could be the culprit you know. I know you didn't want to disturb the lopt and left it in but in reality its better out of the set. I still would remove ALL the external connections from the transformer execpt for the EHT lead and check each connection on the transformer to the transformer metalwork on ohms for shorts or leaks, If nothing look elsewhere. OOOOP's posted this on the wrong V4 thread __________________ Cheers, Trevor. MM0KJJ. RSGB, GQRP, WACRAL, K&LARC. Member

24th May 2010, 2:53 pm	#104
dominicbeesley Octode Join Date: Nov 2004 Location: Hebden Bridge, West Yorkshire, UK. Posts: 1,885	Re: Oh no - another V4! Any advice for me Trevor? I've removed the LOPT and if no contrary advice in the next hour I'm going to remove the perspex top if possible and bake it! Dom

24th May 2010, 3:15 pm	#105
murphyv310 Dekatron Join Date: Sep 2006 Location: Kilmarnock, Ayrshire, UK. Posts: 5,422	Re: Oh no - another V4! At 75C it should be fine I did one at 100c and there was a little distortion, give it a little prod when up to 70c and make sure its not getting soft. __________________ Cheers, Trevor. MM0KJJ. RSGB, GQRP, WACRAL, K&LARC. Member

24th May 2010, 4:34 pm	#106
dominicbeesley Octode Join Date: Nov 2004 Location: Hebden Bridge, West Yorkshire, UK. Posts: 1,885	Re: Oh no - another V4! Righto tis in the oven - Will give it until six o'clock with frequeny checks at 60 degrees the pitch is soft an all looks well! Not sure which way up to stand it while it cooks... Dom

24th May 2010, 7:55 pm	#107
Heatercathodeshort Dekatron Join Date: Jun 2005 Location: Warnham, West Sussex. 10 miles south of DORKING. Posts: 9,147	Re: Oh no - another V4! You may as well bung a few spuds round it at the same time. Seems a pity to waste all that good oven heat on an old LOPT. J.

24th May 2010, 8:22 pm	#108
dominicbeesley Octode Join Date: Nov 2004 Location: Hebden Bridge, West Yorkshire, UK. Posts: 1,885	Re: Oh no - another V4! You might be kidding but I'm going to put in the rest of the roast beef, Yorkshire puds and spuds we had last night to warm up in a minute while the footballs on.... Dom

24th May 2010, 10:39 pm	#109
dominicbeesley Octode Join Date: Nov 2004 Location: Hebden Bridge, West Yorkshire, UK. Posts: 1,885	Re: Oh no - another V4! Well it's had six hours and it's still bubbling! The perspex has warped a little but still useable. I'll leave it overnight and give it a few hours tomorrow morning. On the downside it made my spuds taste a bit funny! Dom

24th May 2010, 10:43 pm	#110
Alistair D Nonode Join Date: Jan 2010 Location: Edinburgh, UK. Posts: 2,008	Re: Oh no - another V4! Who would have thought that an oven thermometer would become a piece of test equipment!!!. Joking aside, does anyone know the temperature range of a domestic electric oven? Al

24th May 2010, 11:41 pm	#111
FRANK.C Heptode Join Date: Feb 2006 Location: Roscommon, Ireland Posts: 732	Re: Oh no - another V4! Hi Al Temperature range of electric oven is usually 35C (as a keep warm function) to 250C. Frank

25th May 2010, 1:36 pm	#112
dominicbeesley Octode Join Date: Nov 2004 Location: Hebden Bridge, West Yorkshire, UK. Posts: 1,885	Re: Oh no - another V4! Well its now had nine hours at over 100degrees and it's still making a ticking noise when I take it out. Is it really still farting out steam? What should I do? It's starting to look very lopsided now - the paxolin sides set at a funny angle and the perspex corona ring holders are quite bent? Dom

25th May 2010, 2:16 pm	#113
murphyv310 Dekatron Join Date: Sep 2006 Location: Kilmarnock, Ayrshire, UK. Posts: 5,422	Re: Oh no - another V4! Hi Stop, I only gave mine about 2 to 3 hours, natural heat will do the rest, hope its all ok. Check it against the readings on OTT's thread. good luck __________________ Cheers, Trevor. MM0KJJ. RSGB, GQRP, WACRAL, K&LARC. Member

25th May 2010, 6:00 pm	#114
dominicbeesley Octode Join Date: Nov 2004 Location: Hebden Bridge, West Yorkshire, UK. Posts: 1,885	Re: Oh no - another V4! To quote Roy Walker: "It's good! But it's not quite right!" Wiring the LOPT back up was a good hour's worth of finger burning fun - switched on and after a bit of twiddling got an .....almost full width picture! EHT is up a bit at just over 10kV (my AVO8 seems to have lost its magnetism so this is an estimate) had to reset all the centring magnets and the frame amplitude and linearity. Focus is a tad sharper and doesn't need to be all the way over. But width is still quite low. I've got to go out now but will try and get measurements from the line drive area again. I really can't think what it will be now other than a problem with the scan coils... Cheers Dom

25th May 2010, 6:08 pm	#115
Heatercathodeshort Dekatron Join Date: Jun 2005 Location: Warnham, West Sussex. 10 miles south of DORKING. Posts: 9,147	Re: Oh no - another V4! Yes Stop and leave it a while to settle. The incredible bubbling, smoke, melted tar, burnt fingers, smells, fumes and frustration when replacing a Pye V4 line output transformer has to be experienced to be believed. Definitely has a 'slaughter house' feeling about it..J.

26th May 2010, 12:26 am	#116
dominicbeesley Octode Join Date: Nov 2004 Location: Hebden Bridge, West Yorkshire, UK. Posts: 1,885	Re: Oh no - another V4! Hee Hee, is fun though - unlike abatoir work... Any ideas what to check next? Dom

26th May 2010, 8:46 am	#117
murphyv310 Dekatron Join Date: Sep 2006 Location: Kilmarnock, Ayrshire, UK. Posts: 5,422	Re: Oh no - another V4! Hi. I've known the width and lin coils to have shorted turns, sometimes they look quite cooked! What does it do with the drive trimmer now? __________________ Cheers, Trevor. MM0KJJ. RSGB, GQRP, WACRAL, K&LARC. Member

26th May 2010, 12:53 pm	#118
dominicbeesley Octode Join Date: Nov 2004 Location: Hebden Bridge, West Yorkshire, UK. Posts: 1,885	Re: Oh no - another V4! Thanks Trevor, I didn't get a chance to turn the chassis over last night before I had to go out. Will retry all the drive bits tonight. Is there a test I can do on the width and lin. controls? It would be good to just know what their resistance, or even better inductance was supposed to be! Is it worth measuring their Q? The width coil was a mass of goo hard to tell whether it was fromt he enamel or the tape. I replaced the tape anyway as there was a risk of a short between the leadout wires. Dom

26th May 2010, 6:07 pm	#119
dominicbeesley Octode Join Date: Nov 2004 Location: Hebden Bridge, West Yorkshire, UK. Posts: 1,885	Re: Oh no - another V4! Hi Lads, Had a spare twenty minutes so went down, resoldered the EHT lead and put the cage back on. Twiddling the line drive trimmer C101 gave the following results... All the way out as pictured below: bright with more EHT (had to readjust height controls) and sharp pictures and full width but wobbly verticals Mid way: dimmer narrower picture - no sign of "kink", less wobbly verticals still a reasonable picture All way in: very weak looking EHT line wouldn't lock, dim picture at about 3/5 width No sign of any kink and these all tried with C99 subbed by a 100pF cap. This all with width control turned fully up (i.e. iron core all the way in). What to check next? Or should I just leave it!? I'd really like to get this running 100% though - including the width control near the middle! How to check the width control coil or should I just rewind it!? Cheers Dom Attached Thumbnails

26th May 2010, 7:28 pm	#120
Steve_P Dekatron Join Date: Sep 2003 Location: Bolton, Greater Manchester, UK. Posts: 6,644	Re: Oh no - another V4! Is the power supply OK at all levels. If not it could cause this sort of thing. C103 if not already changed. 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...?