Vidor 396A Mains/battery portable. - UK Vintage Radio Repair and Restoration Discussion Forum

sparkymike · 22nd Feb 2016, 1:36 pm

I was presented with a Vidor model 396A portable radio last week and it is too good to scrap for parts.
I connected it to the variac and gradually brought the voltage up to normal. I can pick up a few stations on both LW and MW but no foreign broadcasts even though I have connected a throw out aerial to the socket in the lid. There is also a loud hum on parts of the tuning scale range but not everywhere. Could this be household interference? TV ? Sound is slightly distorted although speech can be understood ok.
There is a three position mains tapping at the side of the battery compartment and at the moment the wander plug is in the middle hole. Anyone know which tapping is which , as none are marked on the tagboard.? The internal battery detailslabel is rough, so I was going to print out a better copy, but if anyone has this on file it would save me a lot of time.
Mike.

Herald1360 · 22nd Feb 2016, 1:56 pm

I'd replace the output valve grid coupling cap toot sweet, then measure HT and LT voltages PDQ before doing anything else.

(Sorry if you're already a competent egg sucker)

Once you know you're not risking further damage, if it still misbehaves come back!

The mains selector has 200-220 and 230-250 settings- disconnect the set from the mains and go for the setting that gives the highest resistance reading when looking into the mains lead with an ohmmeter with the set switched to ON. You may need an analogue meter to get a sensible reading, some DMMs don't like inductive loads much.

sparkymike · 22nd Feb 2016, 10:46 pm

Hi Chris,
yes I sussed the mains transformer and readings are 130/ 120 and 111 ohms, so I will replace the wander lead on highest setting.
I have replaced the mains lead with a suitable three core and earthed the chassis and also made sure that the neutral is on the wander plug and not the live side, as that would be easily reached in the battery compartment by an unsuspecting owner in the future..
I briefly tried it tonight and hum has vanished, so next job will be to check the various wax caps. Valve pins are also on the hit list for a clean.
Mike.

sparkymike · 23rd Feb 2016, 3:57 pm

I have now changed the .01 mfd af coupllng capacitor and now much less distortion and much more volume and also need to change the 200 mfd smoothing electrolytic for the heater chain as this is reading very low.
I need to locate a knob for the wavechange, as there is a small crack in it. ((The grub screw is a long type that pases right through the brass boss and into the plastic, so beware of this point if repairing a similar set !!) This knob is the "chickens head type that used to be made by Bulgin I think but it is a smaller version. If anyone knows where I can locate one that would be handy.
Mike.

22nd Feb 2016, 1:36 pm	#1
sparkymike Octode Join Date: Dec 2006 Location: Colchester, Essex, UK. Posts: 1,076	Vidor 396A Mains/battery portable. I was presented with a Vidor model 396A portable radio last week and it is too good to scrap for parts. I connected it to the variac and gradually brought the voltage up to normal. I can pick up a few stations on both LW and MW but no foreign broadcasts even though I have connected a throw out aerial to the socket in the lid. There is also a loud hum on parts of the tuning scale range but not everywhere. Could this be household interference? TV ? Sound is slightly distorted although speech can be understood ok. There is a three position mains tapping at the side of the battery compartment and at the moment the wander plug is in the middle hole. Anyone know which tapping is which , as none are marked on the tagboard.? The internal battery detailslabel is rough, so I was going to print out a better copy, but if anyone has this on file it would save me a lot of time. Mike.

22nd Feb 2016, 1:56 pm	#2
Herald1360 Dekatron Join Date: Feb 2007 Location: Leominster, Herefordshire, UK. Posts: 16,536	Re: Vidor 396A Mains/battery portable. I'd replace the output valve grid coupling cap toot sweet, then measure HT and LT voltages PDQ before doing anything else. (Sorry if you're already a competent egg sucker) Once you know you're not risking further damage, if it still misbehaves come back! The mains selector has 200-220 and 230-250 settings- disconnect the set from the mains and go for the setting that gives the highest resistance reading when looking into the mains lead with an ohmmeter with the set switched to ON. You may need an analogue meter to get a sensible reading, some DMMs don't like inductive loads much. __________________ ....__________ ....\|____\|\|__\|__\_____ .=.\| _---\__\|__\|_---_\|. .........O..Chris....O

22nd Feb 2016, 10:46 pm	#3
sparkymike Octode Join Date: Dec 2006 Location: Colchester, Essex, UK. Posts: 1,076	Re: Vidor 396A Mains/battery portable. Hi Chris, yes I sussed the mains transformer and readings are 130/ 120 and 111 ohms, so I will replace the wander lead on highest setting. I have replaced the mains lead with a suitable three core and earthed the chassis and also made sure that the neutral is on the wander plug and not the live side, as that would be easily reached in the battery compartment by an unsuspecting owner in the future.. I briefly tried it tonight and hum has vanished, so next job will be to check the various wax caps. Valve pins are also on the hit list for a clean. Mike.

23rd Feb 2016, 3:57 pm	#4
sparkymike Octode Join Date: Dec 2006 Location: Colchester, Essex, UK. Posts: 1,076	Re: Vidor 396A Mains/battery portable. I have now changed the .01 mfd af coupllng capacitor and now much less distortion and much more volume and also need to change the 200 mfd smoothing electrolytic for the heater chain as this is reading very low. I need to locate a knob for the wavechange, as there is a small crack in it. ((The grub screw is a long type that pases right through the brass boss and into the plastic, so beware of this point if repairing a similar set !!) This knob is the "chickens head type that used to be made by Bulgin I think but it is a smaller version. If anyone knows where I can locate one that would be handy. Mike.