Ultra 6820 - UK Vintage Radio Repair and Restoration Discussion Forum

ryanbrownin · 20th Aug 2016, 2:35 pm

Hi,

My ultra 6820 displays a single line. When I looked inside I noticed the lopt was making this funny noise that sounded like the whistle of a kettle.

Heatercathodeshort · 20th Aug 2016, 8:21 pm

First move, check C89 1uf. This is the decoupling capacitor on the boost HT line supply to the line oscillator. J

1955APREN · 20th Aug 2016, 11:18 pm

Hi Ryan
Good to hear from you again. Is this 1500 chassis if so a common fault
causing the white line is that one of the tags on the frame output transformer
as broken from the printed circuit. Look at the top right side of the chassis the transformer is in the corner resolder all the pins. The whishle is possible a different fault as John says try the cap but it might be just a loose winding
on the loptx or a another coil possible line lin in any case should not be to big a
problem
regards Derrick
Ps My door is still open regarding your Bush 191

ryanbrownin · 21st Aug 2016, 2:28 pm

Thank you for your responses

The whistle coming from lopt has stopped now and now I can just hear the normal line whistle that you usually hear. I can hear arcing coming from the anode cap when it is connected to the crt the arcing is only faint but I just thought I'd mention it just in case.

Derrick I shall re-solder the transformer when I get my new soldering iron, my current one won't heat up for some reason...

Kind regards,
Ryan

Focus Diode · 24th Aug 2016, 10:47 pm

Nice set. Seeing there's a horizontal white line this clearly suggests the line timebase is functioning. Slight lack of width evident on the left which could be due to the feed resistor to the width control changing value. It's a good idea to check the boost volts as if high can seriously shorten the life of the EHT tray. If lack of width persists with the boost voltage correct suspect the scan correction capacitor.

With the frame collapse problem I agree with the comments re checking the panel close to the frame output transformer. Presumably you've tried a new PCL85/805?

What are the voltages around the PCL85/805?

Cheers,
Brian

ryanbrownin · 25th Aug 2016, 4:48 pm

Hi Brian,

I managed to sort the lack of width that was due to the pots at the back.

I have tried a new PCL805 but it hasn't made a difference, I'll get back to you with the voltages.

Kind regards.

Ryan

dazzlevision · 25th Aug 2016, 5:33 pm

Hello,

There are two 18k 0.5W carbon resistors in the feedback circuit from the (pentode) anode of the PCL805. They can go o/c. Worth checking.

Regards,

Dazzlevision

20th Aug 2016, 2:35 pm	#1
ryanbrownin Pentode Join Date: Jan 2015 Location: Birmingham, West Midlands, UK. Posts: 133	Ultra 6820 Hi, My ultra 6820 displays a single line. When I looked inside I noticed the lopt was making this funny noise that sounded like the whistle of a kettle. Attached Thumbnails

20th Aug 2016, 8:21 pm	#2
Heatercathodeshort Dekatron Join Date: Jun 2005 Location: Warnham, West Sussex. 10 miles south of DORKING. Posts: 9,147	Re: Ultra 6820 First move, check C89 1uf. This is the decoupling capacitor on the boost HT line supply to the line oscillator. J

20th Aug 2016, 11:18 pm	#3
1955APREN Hexode Join Date: Nov 2010 Location: Market Drayton, Shropshire, UK. Posts: 485	Re: Ultra 6820 Hi Ryan Good to hear from you again. Is this 1500 chassis if so a common fault causing the white line is that one of the tags on the frame output transformer as broken from the printed circuit. Look at the top right side of the chassis the transformer is in the corner resolder all the pins. The whishle is possible a different fault as John says try the cap but it might be just a loose winding on the loptx or a another coil possible line lin in any case should not be to big a problem regards Derrick Ps My door is still open regarding your Bush 191

21st Aug 2016, 2:28 pm	#4
ryanbrownin Pentode Join Date: Jan 2015 Location: Birmingham, West Midlands, UK. Posts: 133	Re: Ultra 6820 Thank you for your responses The whistle coming from lopt has stopped now and now I can just hear the normal line whistle that you usually hear. I can hear arcing coming from the anode cap when it is connected to the crt the arcing is only faint but I just thought I'd mention it just in case. Derrick I shall re-solder the transformer when I get my new soldering iron, my current one won't heat up for some reason... Kind regards, Ryan

24th Aug 2016, 10:47 pm	#5
Focus Diode Octode Join Date: Jan 2006 Location: Borough of Gateshead, UK. Posts: 1,420	Re: Ultra 6820 Nice set. Seeing there's a horizontal white line this clearly suggests the line timebase is functioning. Slight lack of width evident on the left which could be due to the feed resistor to the width control changing value. It's a good idea to check the boost volts as if high can seriously shorten the life of the EHT tray. If lack of width persists with the boost voltage correct suspect the scan correction capacitor. With the frame collapse problem I agree with the comments re checking the panel close to the frame output transformer. Presumably you've tried a new PCL85/805? What are the voltages around the PCL85/805? Cheers, Brian Last edited by Focus Diode; 24th Aug 2016 at 10:54 pm.

25th Aug 2016, 4:48 pm	#6
ryanbrownin Pentode Join Date: Jan 2015 Location: Birmingham, West Midlands, UK. Posts: 133	Re: Ultra 6820 Hi Brian, I managed to sort the lack of width that was due to the pots at the back. I have tried a new PCL805 but it hasn't made a difference, I'll get back to you with the voltages. Kind regards. Ryan

25th Aug 2016, 5:33 pm	#7
dazzlevision Dekatron Join Date: Sep 2003 Location: Near Swindon, North Wiltshire, UK. Posts: 3,621	Re: Ultra 6820 Hello, There are two 18k 0.5W carbon resistors in the feedback circuit from the (pentode) anode of the PCL805. They can go o/c. Worth checking. Regards, Dazzlevision Last edited by dazzlevision; 25th Aug 2016 at 5:34 pm. Reason: Added text.