How to repair rebuild a Cybernet CB radio VCO block / can.

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[@Alfa011]

Thank you very, very much for this great video. It will now enable me to replicate the same to repair my old GE and TriStar Cybernet chassis CB radios! Keep the good work Mike!!!!!!!!!

[@argentogoldspier5211]

Mike Thank-you for sharing and explaining so well how to do this. So many people on the internet just race through things and keep little things to themselves. For example you showed the actual values of the cap and diode. People don't always share that kind of stuff and when someone messages them about some detail they just ignore the message. You have no doubt saved a lot of cybernet CBs from the dump and I am in no doubt some CB repair shops that see this will be amazed. You should get some VCO Blocks and repair them and sell them as reconditioned on that auction site everyone uses. I guess the green VCO blocks use the same diode? This is the first of your videos I have watched and look forward to viewing them all. Good work, much appreciated

[@mikesradiorepair]

Thanks for the comment. Yes, use the same NTE diode in the green VCO blocks.

[@SWIZZRADIOS]

Mr mike hello! Thank you for this great instruction. I've done the same with the newer VCO-blocks (orange or green plastic can). The radio was a CYBERNET ARGUS-5000. Best 73s to you...

[@mikesradiorepair]

I just did a green one yesterday. Will be uploading a video of that one soon.

[@garyp5522]

You're not a Technician. You are a surgeon. LOL. Great Video.

[@samiam5557]

Great tips, awesome job.

[@charlieoscar09]

What a brilliant video thanks for this..Will help everyone with Cybernets.The only issue with the green ones i think the Epoxy is solid black and not transparent so its difficult to know were you are..cheers n beers

[@mikesradiorepair]

Every green VCO block I have ever done used the clear epoxy. Even if its opaque it still wouldn't be hard. Since the varactor diode is so close to the edge and on the corner in them it would still be fairly easy. Next time I do a green one I will make a video of it so I can show its location.

[@charlieoscar09]

+MikesRadioRepair Thankyou Mike

[@StalinTheMan0fSteel]

You should make a video solely dedicated to war stories, some of the most laughable and unbelievable repair disasters done by "techs" and "backyard mechanics" alike! 8-)

[@FelixTheHouseFreak]

Mike, what's the value for the ceramic cap next to the electrolytic? I chipped mine because it was too much in the way of the electrolytic. I can't find any schematics for the inside of the VCO. The only one I found looks very similar, has the same resistor values and pin count, but that one only shows 5 ceramic caps while the one I have has 6 of them. There it shows the ceramic cap I chipped and the electrolytic to be on the same line as the cathode of the varactor. It says the ceramic cap is a .01 and the electrolytic is a 10uf 16V

[@mikesradiorepair]

Usually you can see the values of the ceramic caps through the epoxy. Usually have to get the viewing angle just right. Also if you carefully chip away the epoxy the printing on the cap usually stays on the cap. Just a matter of getting to it.

[@FelixTheHouseFreak]

No such luck in this case I'm afraid. All the caps are sorrounded by a lot of fine air bubbles. When I tried chipping away at it the whole face of the capacitor came off. Do you think you might have one somewhere around that you could take a peak at? Otherwise I might just shoot for the .01uf cap and see what happens. Looks like its just meant to decouple the cathode of the varactor.

[@mikesradiorepair]

+FelixTheHouseFreak Ah ha, it goes to the cathode of the varactor. Yes, that should be a .01uf cap. It's a .01uf in pretty much all their vco cans.

[@FelixTheHouseFreak]

Sweet, thanks a lot man! I might upload a video on the finished repair. In my case I'm kinda working with what I've got on hand and I'm going to try using a BB505 varactor. Not quite the same rating as the original but I figure its close enough to not be a problem. Gives about 11 or 12 picofarad @ 3V. The original BB121 or BB122 give 11pf and 13pf respectively at 3V. I made a list of cross references. If this one wont work I'll try buying one of the cross referenced ones. Pulled this out of an 80s cordless telephone. The ceramic disk and the 4.7uf electrolytic are already soldered in place.

[@mikesradiorepair]

FelixTheHouseFreak LOL, we'll if it doesn't work as a CB maybe you'll be able to make a phone call with it. :-)

[@poduck2]

I just found one of these where the can had been opened and then soldered back together, but whoever did it didn't rebuild it. I'm not sure why they would go through the work of pulling off the RF shielding and putting it back on, but not rebuild the VCO. I was wondering though, is the potting necessary? Other than it being much more costly, would there be a problem with the replacement board that guy in the UK sells being put inside the shielding without the potting? After all, I'm lazy, and grinding the old VCO down and cleaning up the mess that comes with that doesn't seem like fun.

[@mikesradiorepair]

Nope, nothing wrong with them. I have the Spectrum Communications VCO modules in stock because some people opt for that instead of rebuilding the original.

[@poduck2]

Thanks. It is nice that people are making replacements for out of production stuff. Too bad not everything can be made in someone's home workshop.

[@carolinapirate2830]

What is the value of the electrolytic capacitor in the VCO block? It is not on the schematic. I have a Midland 79-892 that loses lock after a few minutes. The receive and transmit fades out, and the VCO starts drifting. Spraying component cooler on C5 (10uf tantalum) near the VCO brings it back for a few minutes. I've replaced the other two tantalum capacitors (C4 and C3), and I'm waiting on the 10uF tantalum cap to arrive in the mail. If replacing that does not fix it then I'm probably going to have to do what you did in this video.

[@mikesradiorepair]

10uF / 16V

[@carolinapirate2830]

@@mikesradiorepair Thank you.

[@andrewverran3498]

Why cant you just drill straight through the old eloctrolytic just before where it is seated on the board with the drill press?

[@g1fsh]

and after u knack it completly send it ti Mike and he will do it properly LOL

[@gh778jk]

Mike, Have you ever considered this to get rid of that polyester resin? landainternational.com/index.php?route=product/product&product_id=402 I also had some success with paint stripped that had methylene chloride in it Paddy

[@mikesradiorepair]

gh778jk Products that dissolve epoxy probably wouldn't be a good idea. Fiberglass epoxy circuit boards, epoxy coated capacitors, wire, etc... No doubt it would dissolve the potting compound but it would also dissolve a lot of other parts to. Would probably end up with a gelatinous blob with some metal parts floating around in it.

[@gh778jk]

Mike, You may be pleasantly surprised about this. The two suggestions I made will dissolve fibreglass, but will leave epoxy undamaged. The only product that will dissolve both (as far as I know, and I am an EE, not a chem engineer) is aqua Regia.... but that would dissolve a Mike as well LOL Paddy

[@mikesradiorepair]

gh778jk The product you linked to called "Attack" dissolves epoxy and pretty much any resin or glue. Definitely don't want to be dissolving any Mike's. :-) Though if I wanted to do that I think I still have about 10 gallons of sulfuric acid in one of the chemical cabinets out in the garage.

[@gh778jk]

Sorry, my mistake... it is the methylene chloride that leaves epoxy and Mikes unharmed ( it may take the shine off the later...),not the commercial product. Would it not be simpler just build those boards and pot them up with resin, rather than this neuro-rocket-surgery on them? Seems very laborious doing it this way.... obviously it works, but I can't help thinking there has to be a less infuriating way of doing this.... Paddy

[@rpcomms1]

I dont bother,easier to just buy new replacements vco blocks here www.spectrumcomms.co.uk/CB_Kits.htm