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.

Closed Thread
 
Thread Tools
Old 5th Jun 2018, 12:30 pm   #1
ChasHeater
Triode
 
ChasHeater's Avatar
 
Join Date: Jun 2018
Location: Ash, Surrey, UK.
Posts: 38
Default Some advice On my Ekco AD86

I'm looking for a little guidance. In the past I have managed OK but no man is an island. I have been working on an EKCO AD86 for a while and have restored it visually to look good. Internally I have replaced the electrolytic capacitors with modern equivalents, and recreated the capacitor block where it had been ripped out at some point in the past. On further inspection I have found the output transformer open circuit on the primary winding. I have had a look and don't think I want to try and rewind it. The manufacturers information indicate it to be around 800ohms on the primary and 0.4ohms on the secondary. Does anyone in the community have any suggestions for a replacement? I could keep the original in place and fit a replacement elsewhere. How critical is the primary impedance. The output valve is a Mazda Pen 35/20. Thanks all.
ChasHeater is offline  
Old 5th Jun 2018, 1:06 pm   #2
ms660
Dekatron
 
ms660's Avatar
 
Join Date: Apr 2011
Location: Cornwall, UK.
Posts: 13,454
Default Re: Some advice On my Ekco AD86

I don't have the schematic but if it's a standard output stage then most valve single ended output transformers will work, the valve data suggests approx. 4.5k primary impedance.

Lawrence.
ms660 is offline  
Old 5th Jun 2018, 1:35 pm   #3
Boater Sam
Banned
 
Join Date: Dec 2013
Location: Middlewich, Cheshire, UK. & Winter in the Philippines.
Posts: 3,897
Default Re: Some advice On my Ekco AD86

With a primary resistance of 800 ohm there is possibly going to be 6000 to 8000 turns of fine wire in the winding.
For originality a rewind would be best, there are several forum members who would do so for you at a reasonable cost.
The ratio of primary to secondary with a 4.5k output valve impedance will be 40 to 1. There is an RS universal transformer 210-6475 which will do just fine.
Boater Sam is offline  
Old 6th Jun 2018, 11:33 am   #4
ChasHeater
Triode
 
ChasHeater's Avatar
 
Join Date: Jun 2018
Location: Ash, Surrey, UK.
Posts: 38
Default Re: Some advice On my Ekco AD86

Hi all, thanks for the reply. Bit of an update and disaster! I thought I might have a look myself by unwinding the secondary and seeing if the primary winding was open circuit near the surface. Good news is it was and I now have a measurable primary at around 800ohms. Bad news is that the secondary winding is not re-usable and the cardboard former is dropping apart! Less haste more speed eh? I'll just have to see how this goes, one of the forum members did offer a rewind - Ed in Newcastle. Think I may have burnt my bridges now. Hay Ho.
ChasHeater is offline  
Old 6th Jun 2018, 1:05 pm   #5
Boater Sam
Banned
 
Join Date: Dec 2013
Location: Middlewich, Cheshire, UK. & Winter in the Philippines.
Posts: 3,897
Default Re: Some advice On my Ekco AD86

There is not much to the secondary winding, any gauge of wire close to the original will do if you can buy a bit or claim some from an old wound component.
Why is the original unusable? There is little voltage on it.
If the card former is crumbling, try soaking it with pva to stiffen it up.

You have succeeded doing the hard part in finding the break, carry on!
Boater Sam is offline  
Old 6th Jun 2018, 3:53 pm   #6
Ed_Dinning
Dekatron
 
Join Date: Jan 2004
Location: Newcastle upon Tyne, Tyne & Wear, UK.
Posts: 8,171
Default Re: Some advice On my Ekco AD86

Hi Chas, it should be recoverable if you did not damage the lams. Note that there would normally be a piece of thin gapping paper in between the lam stacks.

Ed
Ed_Dinning is offline  
Old 7th Jun 2018, 10:58 am   #7
ChasHeater
Triode
 
ChasHeater's Avatar
 
Join Date: Jun 2018
Location: Ash, Surrey, UK.
Posts: 38
Default Re: Some advice On my Ekco AD86

HI all many thanks for the replies. The laminations are fine, but the secondary winding copper enamel is peeling, I have ordered some which is fine. I have also sorted the former. This has been like a therapy session, I normally beat myself up when I make a mistake but now I can unload my problems, thanks again.
ChasHeater is offline  
Old 17th Jun 2018, 5:58 pm   #8
ChasHeater
Triode
 
ChasHeater's Avatar
 
Join Date: Jun 2018
Location: Ash, Surrey, UK.
Posts: 38
Default Re: Some advice On my Ekco AD86

Thanks to everyone who previously replied to me over my output transform woes. The good news is the transformer is rewound and that side of things appears to be fine. I have had to replace a couple more old waxy capacitors as one was high and another shorting out. I now have a radio I can safely apply power to and all I get is a slight hum form the speaker. So now I was hoping that someone out there with experience of this model can give me some guidance on the most likely cause for no signal reception. I have been through some fault finding from the manufacturers guide and its pointing towards a valve possibly faulty? But maybe some previous knowledge can point me in the right direction. In the meantime it look great on the sideboard.
ChasHeater is offline  
Old 17th Jul 2018, 5:08 pm   #9
ChasHeater
Triode
 
ChasHeater's Avatar
 
Join Date: Jun 2018
Location: Ash, Surrey, UK.
Posts: 38
Red face A little more help with my EKCO AD86

Hello all, one or two of you may remember I had an issue with the output transformer on my AD86. The good news is that has been fixed! The current state is that I have a radio which powers on and, well, thats about it, not a sniff of any reception. I have been through the EKCO service documentation for the radio and all voltages are correct, bandpass and I.F. windings OK. I have changed the Electrolytic capacitors and a few leaking waxy ones. found a couple of open circuit resistors. The radio will currently warm up after which I get a pronounced hum which then goes away to a slight background hum. My guess is that a valve is the culprit but which one? I did change V2 (VP13C) with a known good one but without any joy. The service documentation says test by substitution of V1-5 but I don't have a full set! Does anyone know what would be the most likely culprit. The line up is: V1 - FC13C, V2 -VP13C (changed), V3 - DD620, V4 - HL13C, V5 - PEN35/20 and a Brimar ID5 rectifier. Even applying a 130K/c to the top cap of V1 gives nothing, though the tests indicate V1 is oscillating. Thanks in advance, it would be nice to get it going. Charlie
ChasHeater is offline  
Old 17th Jul 2018, 7:45 pm   #10
Lloyd 1985
Nonode
 
Lloyd 1985's Avatar
 
Join Date: Jun 2008
Location: Coningsby, Lincolnshire, UK.
Posts: 2,814
Default Re: Some advice On my Ekco AD86

Sorry to ask a daft question, have you tried playing with the sensitivity control? I’ve got the AC86 version, and it’s very fussy about setting that control!

Regards
Lloyd
Lloyd 1985 is online now  
Old 17th Jul 2018, 8:06 pm   #11
crackle
Rest in Peace
 
Join Date: Mar 2011
Location: Basildon, Essex, UK.
Posts: 4,100
Default Re: Some advice On my Ekco AD86

If the heaters are OK then the valves will probably be OK.
Test the audio stage first, by feeding in an external AF signal, e.g. from the earphone socket from another transistor radio.
Then feed the modulated 130khz signal into each IF stage working forwards towards the rf/mixer valve.

Mike
crackle is offline  
Old 17th Jul 2018, 9:36 pm   #12
PJL
Dekatron
 
Join Date: Sep 2005
Location: Seaford, East Sussex, UK.
Posts: 5,997
Default Re: Some advice On my Ekco AD86

First thing I would do is to measure the valve voltages and compare with the service sheet. It's a live chassis set so be careful.
PJL is offline  
Old 18th Jul 2018, 1:35 pm   #13
cathoderay57
Nonode
 
Join Date: Oct 2017
Location: Bristol, UK.
Posts: 2,364
Default Re: Some advice On my Ekco AD86

Hi Charlie, it's usually pointless guessing what might be at fault - you will need to do some simple tests. I agree with advice so far i.e. check the valve voltages starting with the HT at the cathode of the 1D5 rectifier and then at least the anode voltages of the other valves. As suggested, it should be easy to check if the audio stages are working. A finger on a screwdriver blade applied to grid 1 of the output valve (keeping your other hand in your pocket and not touching anything earthed with either hand!) should induce crackling and hum from the speaker followed by grid 1 of the HL13C (louder hum). I don't suggest you rush out buying valves until you work out which one, if any, is faulty. I have checked my stock and I only have FC13 and HL13. These are electrically identical to the FC13C and HL13C except mine are on side-contact (Ct8) bases. If you needed/wanted to use these you'd need to make a valve base adaptor or change the valve base. Cheers, Jerry
cathoderay57 is offline  
Old 19th Jul 2018, 11:50 am   #14
ChasHeater
Triode
 
ChasHeater's Avatar
 
Join Date: Jun 2018
Location: Ash, Surrey, UK.
Posts: 38
Default Re: Some advice On my Ekco AD86

Thanks to all who replied, I will keep looking. I had it powered up last night and in the quiet, (I turned off the BB router, as many SMPSU's as I could and disconnected the powerline plugs) I could hear the slightest glimmer of a heterodyne whistle at a couple of points on the dial which bode well.
ChasHeater is offline  
Closed Thread

Thread Tools



All times are GMT +1. The time now is 8:00 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 - 2023, Paul Stenning.