Faulty LOPT advice - UK Vintage Radio Repair and Restoration Discussion Forum

ryanbrownin · 22nd May 2016, 2:58 pm

Hi,
If the LOPT in a set is faulty and the chances of finding another are slim, what should you do?
The LOPT in my Ferguson 3852 is a jellypot so I'm not sure if it can be repaired. If you know otherwise I'd be grateful to hear from you.

Do you think it would be possible to substitute another chassis into the cabinet?
Any suggestions on what I can do would be great!

Thanks,
Ryan

FERNSEH · 22nd May 2016, 3:15 pm

What chassis is in the 3852? Hybrid or all transistor.

DFWB.

ryanbrownin · 22nd May 2016, 3:25 pm

The chassis is the Thorn 1615 chassis, all transistor.

FERNSEH · 22nd May 2016, 5:41 pm

1615 chassis: I don't think the line output transformer is a jellypot, it's more likely the EHT winding and rectifier and potted together in the same casing.
Have you disconnected the EHT connector from the CRT? If a flame like spark is present at the final anode connector then the EHT rectifier has gone SC, although it is not recommended drawing sparks in solid state receivers.
If the first anode volts are present at the CRT base it can be assumed the line output stage is working.

Read Colourstar's experiences with a 1615 TV:

https://www.vintage-radio.net/forum/...ad.php?t=80528

DFWB.

1955APREN · 22nd May 2016, 10:12 pm

Hi all
For further information on this set, and the faulty Loptx's, see my thread started on 31 July 2015
Regards Derrick

22nd May 2016, 2:58 pm	#1
ryanbrownin Pentode Join Date: Jan 2015 Location: Birmingham, West Midlands, UK. Posts: 133	Faulty LOPT advice Hi, If the LOPT in a set is faulty and the chances of finding another are slim, what should you do? The LOPT in my Ferguson 3852 is a jellypot so I'm not sure if it can be repaired. If you know otherwise I'd be grateful to hear from you. Do you think it would be possible to substitute another chassis into the cabinet? Any suggestions on what I can do would be great! Thanks, Ryan

22nd May 2016, 3:15 pm	#2
FERNSEH Dekatron Join Date: Mar 2005 Location: Gateshead, Tyne and Wear, UK. Posts: 7,444	Re: Faulty lopt advice What chassis is in the 3852? Hybrid or all transistor. DFWB.

22nd May 2016, 3:25 pm	#3
ryanbrownin Pentode Join Date: Jan 2015 Location: Birmingham, West Midlands, UK. Posts: 133	Re: Faulty lopt advice The chassis is the Thorn 1615 chassis, all transistor.

22nd May 2016, 5:41 pm	#4
FERNSEH Dekatron Join Date: Mar 2005 Location: Gateshead, Tyne and Wear, UK. Posts: 7,444	Re: Faulty lopt advice 1615 chassis: I don't think the line output transformer is a jellypot, it's more likely the EHT winding and rectifier and potted together in the same casing. Have you disconnected the EHT connector from the CRT? If a flame like spark is present at the final anode connector then the EHT rectifier has gone SC, although it is not recommended drawing sparks in solid state receivers. If the first anode volts are present at the CRT base it can be assumed the line output stage is working. Read Colourstar's experiences with a 1615 TV: https://www.vintage-radio.net/forum/...ad.php?t=80528 DFWB.

22nd May 2016, 10:12 pm	#5
1955APREN Hexode Join Date: Nov 2010 Location: Market Drayton, Shropshire, UK. Posts: 485	Re: Faulty LOPT advice Hi all For further information on this set, and the faulty Loptx's, see my thread started on 31 July 2015 Regards Derrick