Repairing a Vidor CN359 - someone who's never done this before

[Mike. Watterson]

Actually it's also page 206 Vol 1 in the very first two volume edition of R&TVS, which is all radios in Volume 1 and all TVs in Volume II. Totally identical in later edition. It seems to be gone in the 6 volume 1957-58 edition (index only in Vol. 6). The separate 1958-59 Vol VII is uniform with that edition. Then from 1959-60 till the end the volumes only published slightly and without Volume numbers. You need three different editions to get all the models from 1946 to 1956, the two volume, the four volume and the six volume. There was another edition between 1951 and 1956, but it doesn't seem to have anything not in the other three editions.
You used to get a set of the Trader sheets (I think no models before 1935?) covering up to issue 1900, April 1969, when you joined the BVWS.

If you are only doing the very occasional set then the service data here is the best value. There are other sites for French, USA, Dutch etc models.
UK export and Irish made models usually only have the Manufacturer's se

[newlite4]

Andrew, this is the sort of thing that most of us dream of. Most of us will have found an abandoned forties or fifties woody in a skip or on a verge, but this set looks rather special and would have been expensive when new. Any chance of a front view of this set, all we have to go on so far are some grainy printed images.
Neil

[andrewferguson]

Thank you for saying that - usually I'm the one that just misses out on things like this so it is nice to know that my repeated trips on dustbin day were not in vain!

I haven't yet posted any pictures of the cabinet yet.... because it's not in the best of conditions. It's not horrendous, but the varnish is quite badly scuffed in places. It's also missing two of the knobs on the front, which is a shame as I doubt I'll ever find replacements!

If you want pictures of a set without the scuffs, then the RadioMuseum page for the CN349 has good photos of a almost identically-looking set. I will post photos of mine once I (hopefully) get it working again, but I probably won't tackle the cabinet because re-varnishing etc.. is far beyond my experience (and in all honesty, I don't mind the scuffs - it gives it character!).

Mike, many, many, many thanks for your (very) detailed post on the replacement capacitors and (potentially) resistors. For a beginner link me this was exactly what I was looking for. My only question would be that you said in that post "No X caps on mains.", wile saying I should use X caps in an earlier post. My gut instinct (after a quick google to see what X/Y caps were!) would be to use them where appropriate, is there any reason against doing this?

Also many thanks to those for looking out the service books for the data on the set - most interesting.

I'm at work right now so I don't have access to the set but I'll be drawing up a shopping list of components when I get back - probably from Digikey / Mouser / Farnell - whichever has everything I need in stock and comes out cheapest no doubt!

[paulsherwin]

This radio doesn't appear to use capacitors across the mains, so there is no need for any class X caps. They are mostly found on live chassis sets without mains transformers.

[Mike. Watterson]

I looked through everything because I was trying to make a complete list of Vidor models. I even found a few advertised in the Straits Times (Singapore and obviously fancy export models).
Certainly, Andrew, I'm a little envious of your CN359!

I did once see a Kenwood Chief that had been "fly-tipped". After passing it for nearly a month I lifted it, let it dry out and it worked. Then ordered tools and bowl off eBay. We did have one once, but it had to be left behind when moving between countries.

[electronicskip]

I am the same. I cant pass a piece of abandoned electronics without going for a closer look.
I found a complete set up BBC B inc disk drives monitor once, thrown out by a student outside their door.
People ring me up and say theres an old radio/tv/thingy by the path/road do you want it !

[ajgriff]

Originally Posted by Mike. Watterson

Actually it's also page 206 Vol 1 in the very first two volume edition of R&TVS, which is all radios in Volume 1 and all TVs in Volume II. Totally identical in later edition. It seems to be gone in the 6 volume 1957-58 edition (index only in Vol. 6). The separate 1958-59 Vol VII is uniform with that edition. Then from 1959-60 till the end the volumes only published slightly and without Volume numbers. You need three different editions to get all the models from 1946 to 1956, the two volume, the four volume and the six volume. There was another edition between 1951 and 1956, but it doesn't seem to have anything not in the other three editions.

Not quite, but close. I know it's slightly off-topic but if anyone's interested in maximum model coverage have a look at this thread and in particular post #17:

https://www.vintage-radio.net/forum/...d.php?t=155437

Alan

[andrewferguson]

After several attempts yesterday evening as well as tonight, I've come to the conclusion that I don't have the time during the week to work on this. So that's why I likely won't be posting any updates until the weekend - I've not given up!

[andrewferguson]

I think it is time for a long overdue update on this. I did try to individually identify the the wax capacitors in the radio, but the solid core wiring made this difficult because I couldn't "move around" the capacitors to see their values. (I didn't want to remove them to see because if I did, then I would never be able to work out the right connections to put their replacements).

So I'm going for an alternative approach. As far as I can see everything looks original, so I'm going to trust the schematic (and Mike's advice) when ordering replacements, and hope I don't have to order anything else later on (along with the postage costs accompanying this).

I've looked on Farnell for the parts, and come up with the following. I also added in C35 (a 50uF 12V electrolytic) and C14 (a 0.005uF, added in because it was the only remaining "large" capacitors that I wasn't buying). The list is attached as an image, for those that prefer that, and I've also stuck it in an HTML page so the links to the Farnell parts are click-able.

I know this is all probably looking like Yak Shaving from the perspective of those that are more experienced than me, but I'm a bit nervous of buying everything and only to find "Oh, I ordered the RinkyDink capacitors and the radio actually needs the ThinyMaBob capacitors". I don't suppose that some kind soul would be able to briefly confirm that the parts I'm going to order are the right kind?

(Part of the reason for all of this pedantic-ness is that I'm trying to avoid paying the £4 postage multiple times when I - inevitably - order the wrong parts. In that mind, I've also stuck a 150ohm 1W resistor (replacement for R25) in the basket as Mike mentioned that was the only "really critical" one - as their only a few pence, is there any others I should get?)

[Mike. Watterson]

I buy resistors about 1000 at a time and capacitors about 100 at a time from Asia. Often $0 to $2 postage and 1/2 to 1/10th of price Maplin used to charge. However you wait 4 to 8 weeks!

Your list seems reasonable, but I'm giving no warranty.

[andrewferguson]

I often do that too, however on this occasion I decided to use Farnell, for two reasons:
a) When buying high-voltage components, I want to be sure they are not fakes. I've had a few fakes when getting stuff cheap from China, and I don't have a way of testing the capacitors prior to installation in the radio.
b) I want to get the parts soon - the radio has been sitting for several years. I'm fully aware that if I don't attempt to fix it now when I have (limited) free time, it'll go back to the shed and sit for another few years!

[Mike. Watterson]

Farnell was often my preferred supplier when I worked in Electronics.

I removed the Xenon tube and 300uF cap from the flash PCB in a single use camera. Added a toggle switch to power it. 1uF 630V met poly instead of the 300uF. Two miniature 1M resistors in series from + out to "+ terminal" (one 2.2M might breakdown!). A neon (with 100nF in parallel) in series between "- terminal" and 0V. There should only be a single blip as the internal capacitor charges. Flash rate is external leakage at about 300V. You can measure Giga Ohms by timing a very slow flash.
Virtually every Hunts and paper cap lights it solid. Curiously all my 50V ceramic discs pass!

Take care to short pins of a non-leaky cap. A 1uF charged on it might be lethal! My Grown Up EE kids found it fascinating that you could safely hold the terminals without a cap, and then the almighty bang discharging a 400V 1uF plastic dielectric cap on a metal surface. They deal with logic level stuff. One did want a generator for an isolator demo and I sent him off to buy a Cattle fence energiser at the local Co-Op (simply called a 'Fencer' here).

I have an older one from a scrap flash gun that does 600V. I have it in a box with a 20uA meter instead of a neon. Any movement is a fail. It can be used with a VVM or 10M DVM to measure Vce or Vcb or diode reverse voltage as the 2M Ohms series resistance means the semiconductor isn't damaged. I've selected on test a 1N4148 as a high voltage regulator using it. A simple oscillator and an old car ignition coil will work, but I doubt that even scrap yards have ones from the days of mechanical points.

Electrolytics are easily tested using current limit and a 30V PSU. Even if 450V, you can reform or see if they are leaky. OK ones should be less than 1mA. I set limit to 20mA and start at 10V to reform.
Dried out parts will fail on ESR and usually value too.

[andrewferguson]

Time for an update - and it's good news.

The radio now works! Over the course of yesterday morning and afternoon all the wax capacitors were replaced. I'm not experienced enough to attempt to restuff them (nor are the originals in good condition, nor are the replacements suitable for restuffing), but I'm keeping all the originals in a tub in case I ever fancy restuffing them at a later date.

With all the capacitors replaced, I took the radio outdoors (you can never be too sure), connected a ~20 foot piece of wire lying across the garden as an aerial, and turned it on. It came on first time, and to my amazement all the incandescent bulbs in the display worked. I was able to pickup many, many stations across the four bands (LW, MW, SW1, SW2).

I've attached a photo of the radio as I was testing it. It's still out of the cabinet, and please ignore the two bits of wood screwed to the bottom (they allowed me to balance it upside down in order to access the capacitors).

The only slight problem is that I couldn't find one of the wax capacitors, and therefore I have a single capacitor leftover that I could not replace. It's a 0.01uF capacitor, so is either C30 or C33 in the schematic I have. Attached is a snippet of the schematic showing how C30 and C33 fit into the circuit, I hope it's specific and cropped enough to be permitted under the forum rules. I've also attached a photo of the other 0.01uF capacitor (the one I managed to find and replace) with a paperclip for size. Since the radio works, I'm inclined to leave as-is, unless the capacitor could damage the set in some way, in which case I'll try and reverse-engineer the schematic to work out where the missing wax capacitor is. Thoughts?

Some post-repair questions:
1.) Now that I've got it working, and while I've still got the chassis out of the cabinet, is there anything else I should do? I'll probably give the front of the dial glass a quick clean (not the back - I know from reading other posts how easily the markings come off).
2.) Two of the knobs are missing. I don't suppose anyone here has a couples of spares? I've attached a photo of the front and rear of one of the knobs, and amhappy to pay a few pounds + postage to complete my set.
3.) Is it advisable to replace the power cable? It still has what I imagine is the original cable, a fabric-y one which looks fine to me. I'm currently inclined to leave it as-is. (I'll only ever be using the radio when I'm in the room, so I'll be able to keep an eye on it).
4.) I left the RadioSpares replacement 16/32 uF capacitor in the radio, but completely disconnected all of it's leads. Taking it out would leave an unsightly hole in the chassis, I assume it is OK to leave in?

Finally, and most importantly, I would like to say a huge thanks to the kind folks here that have helped me get this running. Particularly Mike - without your detailed parts list I would never have managed to even attempt a repair.

[Mike. Watterson]

You can buy fabric covered "rubbery" mains cables. They are sold to replace cables on irons and farming gear. Hence our famers Dairy Co-op sells them by pre-packed length.

You should be able to trace wires to magic eye and volume control to find missing cap location. Cap at magic eye might be on its socket at the front panel?

Eye looks good and bright. They wear out fast.

[Mike. Watterson]

Oh, and congratulations!

You can mould knobs or use a set of four similar knobs.

[Sideband]

Excellent work and well done on getting an unusual, possibly rare radio working. It's looking good and you are very lucky to have a bright tuning indicator. Most originals are far too weak to see even in a darkened room and EM34 replacements are eye-wateringly expensive.....if you can find one that is! There are some Russian subs that can be used with modifications but fortunately you won't have to bother.

[andrewferguson]

Ah, Mike, you've nailed it again. The capacitor was right next to the socket for the magic eye. I'll replace that later this week.

I'd never heard of a "magic eye" before this thread. I've tried several searches online, but can't quite get my head around what it actually is doing. Is it part of the amplification or just an indicator. I've also now looked on ebay for the prices of replacements - eek! This will sound like a really stupid question, but will the radio function as normal if the magic eye is removed? I'm basically wondering if there is a way to preserve the lifespan of the magic eye when using the radio for daily use, keeping it for more "special" uses.

As always, feel free to laugh at my lack of knowledge on these things. I really don't know much about what I'm talking about!

[LyntonP]

Looks as if you are making a great job. Don't worry about the lack of knowledge, I'm in the same boat and sinking fast! The other members of the forum are very knowledgeable and are always happy to help.

[Mike. Watterson]

The Magic Eye is only an indicator, though most have an internal amplifier triode to drive the deflection. Most are simple CRTs (Cathode Ray Tubes).

The modern equivalent is an LED or LCD bargraph. Meters (moving coil with a needle) are rare now, but have been used as tuning indicators before Magic Eyes (1935) and on transistor gear.

This was a lot of research and work. I don't know the guy, but he is a Radio Museum member:
http://www.magiceyetubes.com/patterns.htm

Radio Museum Articles
https://www.radiomuseum.org/forum/ma..._patterns.html
https://www.radiomuseum.org/forum/hi...c_eye_led.html

Article by ex-Grundig radio designer
https://www.radiomuseum.org/forum/ho...hread_id=50704

Other indicators and timeline of tuning indicators
https://www.radiomuseum.org/forum/vi...al_meters.html

[Mike. Watterson]

Originally Posted by andrewferguson

The capacitor was right next to the socket for the magic eye. I'll replace that later this week.
I'm basically wondering if there is a way to preserve the lifespan of the magic eye when using the radio for daily use, keeping it for more "special" uses.

The Vidor CN359 is hardly an all day every day radio like late 1950s early 1960s valve sets with VHF-FM.
I've always thought a slightly depressible tuning shaft operating a switch connecting the HT voltage would have been good. However it would have added too much cost, the glowing green was thought pretty and the makers didn't care about life of parts, they knew the paper dielectric capacitors used had about 10 years life and knew ways round it such as not using paper or a hermetically sealed case.

Don't worry about it, or fit an insulated 250V DC rated toggle switch on a hole on the rear panel (won't deface cabinet) that disconnects the HT (approx 200V) to the magic eye socket.