Pye D18T Focus Problem - Page 2 - UK Vintage Radio Repair and Restoration Discussion Forum

ScreenSaver · 2nd Oct 2006, 4:42 pm

Grandata are still listing the BY8420 (24KV) as available at 45p each - RS and Farnell seem to have discontinued the whole BY84xx range. Non-ROHS probably.

ScreenSaver

DoctorWho · 2nd Oct 2006, 5:52 pm

Sean - Thanks for your input, if you have any other suggestions I'd be grateful to hear them, I get the impression that this is not an uncommon problem.

Andy - Thanks for looking, I too found the same problem with RS and CPC, everything high voltage seems to be discontinued.

Screensaver - Thanks for the info about Grandata, I didn't even know about this company, I have just ordered a few of these from them, I'll let you know how I get on with them

Thanks again.

Peter.

DoctorWho · 5th Oct 2006, 11:55 am

Well the only high voltage diode I could obtain was a TV20D2 which has a 20kv limit, so I obtained one of these and duly fitted it.

The picture then obtained was far worse than with the EY51 in place, it ended up being just foggy "ghosted" images.

Unfortunately the diode seems to have made the LOPT unhappy as it will now not work at all with an EY51 and will only work with the diode, which gives poor results, the picture was a great deal better with the valve rectifier. I have even tried a new EY51 just in case, but no go, the heater does not even light up.

Has this wrecked the LOPT? Would a different rectifier perhaps do a better job, if so does anyone know where I can get one as every supplier I have tried is out of stock.

Failing all of this, does anyone have a spare LOPT?

Any advice appreciated.

Peter.

DoctorWho · 5th Oct 2006, 11:59 am

I have just also noticed that the set has a MW22-18 instead of an MW22-14, is this likely to cause any problems? It must have had the tube for years?

Thanks again.

Peter.

beery · 5th Oct 2006, 12:31 pm

Hi Peter,
when you connect the silicon diode you need to make sure that you connect the cathode end directly to the EHT lead and not via the tag where the EY51 was.
The problem with these loptys could quite reasonably be due to leaky EHT rectifier heater windings and this is where a silicon diode can really help.

Cheers
Andy

DoctorWho · 5th Oct 2006, 1:00 pm

Thanks for the clarification Andy, I have now done this, but it makes no difference, I still have a blurred defocussed mess which now does not even fill the screen. Am I right here to suspect the LOPT as it was originally a good picture initially, now there's just mush and no picture at all, you can just see shadows change with the scenes, but it's so blurred that you can't make anything out, the fact that it also does not fill the screen any more makes me suspicious of the LOPT, if that is the case then it must have been failing all along and been the cause of the problem?

Does anyone have a spare LOPT for this set that they would be willing to sell me please?

Peter.

Danny · 6th Oct 2006, 12:19 am

Hi
There is still a possibility its not LOPT trouble - the drive could be low.
Have you tried a new line output bottle even if the set has had one already?
What happens if you move the width control up and down?
It's really meter time; check the grid of the line output valve and see what's on it.

Danny

DoctorWho · 6th Oct 2006, 10:50 am

Yes I did, I put in another PL38, but no difference.

I'll take some voltage readings.

Thanks Danny,

Peter.

2nd Oct 2006, 4:42 pm	#21
ScreenSaver Retired Dormant Member Join Date: Aug 2006 Location: London Posts: 19	Re: Pye D18T Focus Problem Grandata are still listing the BY8420 (24KV) as available at 45p each - RS and Farnell seem to have discontinued the whole BY84xx range. Non-ROHS probably. ScreenSaver

2nd Oct 2006, 5:52 pm	#22
DoctorWho Rest in Peace Join Date: Apr 2005 Location: Devon Posts: 850	Re: Pye D18T Focus Problem Sean - Thanks for your input, if you have any other suggestions I'd be grateful to hear them, I get the impression that this is not an uncommon problem. Andy - Thanks for looking, I too found the same problem with RS and CPC, everything high voltage seems to be discontinued. Screensaver - Thanks for the info about Grandata, I didn't even know about this company, I have just ordered a few of these from them, I'll let you know how I get on with them Thanks again. Peter.

5th Oct 2006, 11:55 am	#23
DoctorWho Rest in Peace Join Date: Apr 2005 Location: Devon Posts: 850	Re: Pye D18T Focus Problem Well the only high voltage diode I could obtain was a TV20D2 which has a 20kv limit, so I obtained one of these and duly fitted it. The picture then obtained was far worse than with the EY51 in place, it ended up being just foggy "ghosted" images. Unfortunately the diode seems to have made the LOPT unhappy as it will now not work at all with an EY51 and will only work with the diode, which gives poor results, the picture was a great deal better with the valve rectifier. I have even tried a new EY51 just in case, but no go, the heater does not even light up. Has this wrecked the LOPT? Would a different rectifier perhaps do a better job, if so does anyone know where I can get one as every supplier I have tried is out of stock. Failing all of this, does anyone have a spare LOPT? Any advice appreciated. Peter.

5th Oct 2006, 11:59 am	#24
DoctorWho Rest in Peace Join Date: Apr 2005 Location: Devon Posts: 850	Re: Pye D18T Focus Problem I have just also noticed that the set has a MW22-18 instead of an MW22-14, is this likely to cause any problems? It must have had the tube for years? Thanks again. Peter.

5th Oct 2006, 12:31 pm	#25
beery Heptode Join Date: Jun 2006 Location: Ware, Hertfordshire, UK. Posts: 988	Re: Pye D18T Focus Problem Hi Peter, when you connect the silicon diode you need to make sure that you connect the cathode end directly to the EHT lead and not via the tag where the EY51 was. The problem with these loptys could quite reasonably be due to leaky EHT rectifier heater windings and this is where a silicon diode can really help. Cheers Andy

5th Oct 2006, 1:00 pm	#26
DoctorWho Rest in Peace Join Date: Apr 2005 Location: Devon Posts: 850	Re: Pye D18T Focus Problem Thanks for the clarification Andy, I have now done this, but it makes no difference, I still have a blurred defocussed mess which now does not even fill the screen. Am I right here to suspect the LOPT as it was originally a good picture initially, now there's just mush and no picture at all, you can just see shadows change with the scenes, but it's so blurred that you can't make anything out, the fact that it also does not fill the screen any more makes me suspicious of the LOPT, if that is the case then it must have been failing all along and been the cause of the problem? Does anyone have a spare LOPT for this set that they would be willing to sell me please? Peter.

6th Oct 2006, 12:19 am	#27
Danny Heptode Join Date: Jul 2003 Location: North Walsham, Norfolk, UK. Posts: 516	Re: Pye D18T Focus Problem Hi There is still a possibility its not LOPT trouble - the drive could be low. Have you tried a new line output bottle even if the set has had one already? What happens if you move the width control up and down? It's really meter time; check the grid of the line output valve and see what's on it. Danny

6th Oct 2006, 10:50 am	#28
DoctorWho Rest in Peace Join Date: Apr 2005 Location: Devon Posts: 850	Re: Pye D18T Focus Problem Yes I did, I put in another PL38, but no difference. I'll take some voltage readings. Thanks Danny, Peter.