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 Radio (domestic)

Notices

Vintage Radio (domestic) Domestic vintage radio (wireless) receivers only.

Reply
 
Thread Tools
Old 10th May 2024, 9:21 am   #1
mancunian69
Pentode
 
mancunian69's Avatar
 
Join Date: Apr 2013
Location: Manchester, UK.
Posts: 193
Default Ekco A455

Hi all, I have an Ekco A455 solid state set in for repair.
I have recapped all the electrolytics, powered it up and all I can hear is white noise, no audio.
Does anyone have an idea what I can do next?

I have a feeling it could be something to do with the IF module.
Rgds
Michael.
mancunian69 is offline   Reply With Quote
Old 10th May 2024, 9:30 am   #2
dazzlevision
Dekatron
 
Join Date: Sep 2003
Location: Near Swindon, North Wiltshire, UK.
Posts: 3,695
Default Re: Ekco A455

The Mullard module contains AF11x series transistors which are subject to the "tin whiskers" effect. You could try tapping the module to see if that causes a response (sometimes the radio bursts into life for a short time). Almost all of the radio's RF and IF circuitry is inside this.

Otherwise, try a finger hum test on the volume control's slider (set to max vol). If that produces a hum, then the module is very likely faulty and will have to be opened up.
dazzlevision is offline   Reply With Quote
Old 10th May 2024, 9:34 am   #3
sexton_mallard
Heptode
 
sexton_mallard's Avatar
 
Join Date: Sep 2013
Location: Ellesmere, Shropshire, UK & Co. Cork, Ireland.
Posts: 527
Default Re: Ekco A455

Check the wavechange switch as well. This is a problem on my A455 where it is intermittent and all I hear is static when it 'breaks'.
__________________
Dom

Less snakes...more ladders!
sexton_mallard is offline   Reply With Quote
Old 10th May 2024, 9:43 am   #4
Station X
Moderator
 
Station X's Avatar
 
Join Date: Jan 2003
Location: Ipswich, Suffolk, IP4, UK.
Posts: 21,628
Default Re: Ekco A455

Check voltages?
Inject signals?
__________________
Graham. Forum Moderator

Reach for your meter before you reach for your soldering iron.
Station X is online now   Reply With Quote
Old 10th May 2024, 11:27 am   #5
Nickthedentist
Dekatron
 
Nickthedentist's Avatar
 
Join Date: Jan 2005
Location: Oxford, UK.
Posts: 18,130
Default Re: Ekco A455

Quote:
Originally Posted by Station X View Post
Check voltages?
Inject signals?
This book will tell you all you need to know, in a very down to earth way:
https://www.vintage-radio.info/download.php?id=361

Apologies if you know much more about radio repair than you first post led us to believe
Nickthedentist is offline   Reply With Quote
Old 10th May 2024, 11:36 am   #6
paulsherwin
Moderator
 
paulsherwin's Avatar
 
Join Date: Jun 2003
Location: Oxford, UK
Posts: 28,460
Default Re: Ekco A455

As said in #2, it's very likely that one or more of the AF11x transistors is bad. I've no idea how easy it is to get inside the module with this model. There's plenty of info about AF11x problems and solutions if you search the forum.
paulsherwin is online now   Reply With Quote
Old 11th May 2024, 2:52 pm   #7
mancunian69
Pentode
 
mancunian69's Avatar
 
Join Date: Apr 2013
Location: Manchester, UK.
Posts: 193
Default Re: Ekco A455

Thanks guys. I will look into it further.
I can say right now that the white noise level is the same regardless of the volume position. I'll take a look and the band selector next before opening the module.

Michael.
mancunian69 is offline   Reply With Quote
Old 11th May 2024, 3:10 pm   #8
paulsherwin
Moderator
 
paulsherwin's Avatar
 
Join Date: Jun 2003
Location: Oxford, UK
Posts: 28,460
Default Re: Ekco A455

Ah, constant white noise unvarying with the volume setting normally suggests a bad transistor in the first AF stage (OC75?). Any OC71/AC126 type should be OK - just try whatever you have to hand.
paulsherwin is online now   Reply With Quote
Old 12th May 2024, 6:33 pm   #9
mancunian69
Pentode
 
mancunian69's Avatar
 
Join Date: Apr 2013
Location: Manchester, UK.
Posts: 193
Default Re: Ekco A455

I don't normally work on solid state sets and have no transistors at all. I'll have to look online, unless of course a member would like to donate one.
I have the IF module out now, which wasn't difficult. I will try the A/F idea before the module.
mancunian69 is offline   Reply With Quote
Reply

Thread Tools



All times are GMT +1. The time now is 4:28 pm.


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 - 2024, vBulletin Solutions, Inc.
Copyright ©2002 - 2024, Paul Stenning.