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.

Reply
 
Thread Tools
Old 13th Jan 2021, 6:47 pm   #61
em536716
Pentode
 
em536716's Avatar
 
Join Date: Dec 2017
Location: Guildford, Surrey, UK.
Posts: 103
Default Re: My newly found Marconi 707

Quote:
Originally Posted by mark pirate View Post
I would steer well clear of NOS capacitors, in my experience they are often leaky and have shifted in values.

With a set of this rarity & value, I would only use new high quality components.

I always use high quality caps from these guys: https://www.justradios.com/
They stock a lot of values not obtainable elsewhere, and the postage is quick too. I have no connection, other than being a very satisfied customer.


Mark

Cheers Mark.

Iíve actually bought most of the RF Mica caps from justradios. Brilliant quality stuff.
em536716 is offline   Reply With Quote
Old 13th Jan 2021, 9:09 pm   #62
Al (astral highway)
Dekatron
 
Al (astral highway)'s Avatar
 
Join Date: Nov 2006
Location: London, UK.
Posts: 3,285
Default Re: My newly found Marconi 707

Quote:
Originally Posted by em536716 View Post

..., but unfortunately has not revitalised the failing parts of the woodgrain which appears to be lifted and near to flaking off on the top of the cab.

Hey Ed, this sounds like the wood veneers getting unstuck, very common with age, heat and dessication.



Quote:
Originally Posted by em536716 View Post

When time comes to work on the TV portion of the set, I will be installing solid state diode on the underside,




Good move. I have HER608's here yours FOC.



Pop a few in series for good measure They're 6A 1000 PIV rated IIRC. Please acknowledge here and then PM me if interested.



Quote:
Originally Posted by em536716 View Post
.


Any suggestions for freeing up the tuning control would be well appreciated!

I'd just go softly softly and get some Servisol in there. Sometimes it can help to soften up solidified grease/gunk with topical application of heat with a hair dryer. This isn't a specific to your set, just in general.
__________________
Al

"Plans are useless but planning is indespensible..." (Eisenhower).
Al (astral highway) is online now   Reply With Quote
Old 13th Jan 2021, 10:13 pm   #63
Heatercathodeshort
Dekatron
 
Heatercathodeshort's Avatar
 
Join Date: Jun 2005
Location: Warnham, West Sussex. 10 miles south of DORKING.
Posts: 7,745
Default Re: My newly found Marconi 707

Use the original U52/5U4G H.T. rectifier. J.
Heatercathodeshort is offline   Reply With Quote
Old 13th Jan 2021, 10:37 pm   #64
em536716
Pentode
 
em536716's Avatar
 
Join Date: Dec 2017
Location: Guildford, Surrey, UK.
Posts: 103
Default Re: My newly found Marconi 707

Quote:
Originally Posted by Heatercathodeshort View Post
Use the original U52/5U4G H.T. rectifier. J.
Iíll be keeping original HT rectifier. Contemplating using solid state diode for EHT.
em536716 is offline   Reply With Quote
Old 13th Jan 2021, 11:44 pm   #65
rambo1152
Nonode
 
rambo1152's Avatar
 
Join Date: May 2010
Location: Manchester, UK.
Posts: 2,415
Default Re: My newly found Marconi 707

Quote:
Originally Posted by em536716 View Post

Iíve actually bought most of the RF Mica caps from justradios. Brilliant quality stuff.
How many of these were you intending to replace Ed?
__________________
--
Graham.
G3ZVT
rambo1152 is offline   Reply With Quote
Old 13th Jan 2021, 11:51 pm   #66
em536716
Pentode
 
em536716's Avatar
 
Join Date: Dec 2017
Location: Guildford, Surrey, UK.
Posts: 103
Default Re: My newly found Marconi 707

Quote:
Originally Posted by rambo1152 View Post
Quote:
Originally Posted by em536716 View Post

Iíve actually bought most of the RF Mica caps from justradios. Brilliant quality stuff.
How many of these were you intending to replace Ed?

Iíve ordered a few different values but only the two Domino type ones which are leaky. Iíve carefully checked the others and they actually appear OK. So for now I will leave them be.
em536716 is offline   Reply With Quote
Old 14th Jan 2021, 10:43 am   #67
peter_scott
Nonode
 
peter_scott's Avatar
 
Join Date: May 2003
Location: Edinburgh, UK.
Posts: 2,593
Default Re: My newly found Marconi 707

Mica capacitors are very rarely faulty.

Peter
peter_scott is offline   Reply With Quote
Old 14th Jan 2021, 10:55 am   #68
HamishBoxer
Dekatron
 
HamishBoxer's Avatar
 
Join Date: Aug 2007
Location: W.Butterwick, near Doncaster UK.
Posts: 7,710
Default Re: My newly found Marconi 707

I know this has probably been asked before but is there any import duty when ordering from Just Radio?
__________________
G8JET BVWS Member and V.M.A.R.S
HamishBoxer is online now   Reply With Quote
Old 14th Jan 2021, 12:15 pm   #69
mark pirate
Dekatron
 
mark pirate's Avatar
 
Join Date: Mar 2008
Location: Worthing, West Sussex, UK
Posts: 4,913
Default Re: My newly found Marconi 707

Quote:
is there any import duty when ordering from Just Radio?
I have had many orders & have never paid any duty.


Mark
mark pirate is online now   Reply With Quote
Old 14th Jan 2021, 12:45 pm   #70
HamishBoxer
Dekatron
 
HamishBoxer's Avatar
 
Join Date: Aug 2007
Location: W.Butterwick, near Doncaster UK.
Posts: 7,710
Default Re: My newly found Marconi 707

Thank you Mark.
__________________
G8JET BVWS Member and V.M.A.R.S
HamishBoxer is online now   Reply With Quote
Old 14th Jan 2021, 1:17 pm   #71
murphyv310
Dekatron
 
murphyv310's Avatar
 
Join Date: Sep 2006
Location: Kilmarnock, Ayrshire, UK.
Posts: 4,356
Default Re: My newly found Marconi 707

Quote:
Originally Posted by Heatercathodeshort View Post
Use the original U52/5U4G H.T. rectifier. J.
The 5U4/U52 are directly heated valves with a filament, although the surge is less than using a silicon or selenium rectifier, the voltage across the HT Line rises very quickly and doesn't stabilise to its running voltage until the load increases with the other valves warmed up.

On a set that is only used rarely I'd advocate using the likes of a GZ33 or GZ37 , being an indirectly heated valve the warm up time is much longer so its kinder to smoothing capacitors and other components, the peak surge voltage will never reach what it was with the 5U4 or silicon etc.
__________________
Cheers,
Trevor
Keep safe everyone.

Last edited by murphyv310; 14th Jan 2021 at 1:23 pm.
murphyv310 is offline   Reply With Quote
Old 14th Jan 2021, 1:46 pm   #72
Al (astral highway)
Dekatron
 
Al (astral highway)'s Avatar
 
Join Date: Nov 2006
Location: London, UK.
Posts: 3,285
Default Re: My newly found Marconi 707

Quote:
Originally Posted by em536716 View Post

Contemplating using solid state diode for EHT.

Great, so would you like me to pop some in the post to you?
__________________
Al

"Plans are useless but planning is indespensible..." (Eisenhower).
Al (astral highway) is online now   Reply With Quote
Old 14th Jan 2021, 5:18 pm   #73
em536716
Pentode
 
em536716's Avatar
 
Join Date: Dec 2017
Location: Guildford, Surrey, UK.
Posts: 103
Default Re: My newly found Marconi 707

Quote:
Originally Posted by astral highway View Post
Quote:
Originally Posted by em536716 View Post

Contemplating using solid state diode for EHT.

Great, so would you like me to pop some in the post to you?

Thanks for the Offer, Astral Highway, but Iíve got some here I can make use of
em536716 is offline   Reply With Quote
Old 14th Jan 2021, 5:20 pm   #74
em536716
Pentode
 
em536716's Avatar
 
Join Date: Dec 2017
Location: Guildford, Surrey, UK.
Posts: 103
Default Re: My newly found Marconi 707

Hi everyone.

All replacement capacitors are now finally here, so will get started and post some updates soon. Iíll see if I can link some YouTube videos as well, as a visual aid.

Thanks,
Ed
em536716 is offline   Reply With Quote
Old 14th Jan 2021, 7:40 pm   #75
draenog
Tetrode
 
draenog's Avatar
 
Join Date: Oct 2009
Location: Chepstow, Monmouthshire, UK.
Posts: 56
Default Re: My newly found Marconi 707

BTW, I notice from your pictures that you have the tuning dial glass in place. This is pretty much irreplaceable and can easily be accidently broken shifting the heavy chassis around. When working on my pre-war TVs for any length of time I always remove it, putting it in a safe place until the work is complete.
draenog is offline   Reply With Quote
Reply

Thread Tools



All times are GMT. The time now is 8:28 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 - 2021, vBulletin Solutions, Inc.
Copyright ©2002 - 2020, Paul Stenning.