SBE Console V no modulation

[NightThumper]

Well one month to the day my beautiful SBE Console V decided to quit modulating. It shows a dead key of 5 watts on AM and as expected no carrier on SSB. When the mic is keyed I can say AUDIO, PEP reads about 17 watts and it immediately drops back to a 5 watt carrier. The Console V receives both AM/SSB from other stations just fine. It transmits audio for about 1 second before no audio is hear through my monitoring radio. (both AM/SSB). Three different mics, same result.

I can immediately unkey/key and it does the same again and again and again.

Looking for some assistance on pointing me in the right direction for trouble shooting. Don’t mind sending it off to someone for repair its a very nice radio.

Thanks
Brad

 

[NZ8N]

Check the Speech Compressor add-on board between the Mic input and the main board.
http://www.cbtricks.com/radios/sbe/sbe_27cba_sidebander_iv/graphics/27cb_a_39cb_40cb_sm.pdf
Page 33 of the service manual has the schematic and board layout of the compressor.
That is where I would start, check the voltages of this board in Transmit, see if they fall off after the first few seconds.

 

[Unit 75]

Sounds like the radio is due for a re-cap. I did one a few years back that fixed a similar audio problem. Man, I remembered those foil boards.....and all those tiny caps.
If your radio is a keeper, I would highly recommend replacing all the electrolytic capacitors and then re-aligning the radio, Should last you another decade or two after that I think that would be the best choice so nothing else goes wrong with it due to a dried out or shorted electrolytic. They were nice radios.

 

[nomadradio]

A reputable shop will recommend replacing all the electrolytic capacitors. Two good reasons for this. If they send it home with old caps still in it, you'll be unhappy when the next capacitor fails way too soon.

Second, a failed capacitor can hide other problems. Replacing them doesn't always fix every fault. But finding them will be a lot easier without bad capacitors muddying the water and making it tougher to troubleshoot.

More than once a horse trader has brought us one of those. He'll just want the two or three caps causing trouble to get replaced. The next few capacitors to go bad will be the buyer's problem. Keeps his costs lower before unloading the radio.

Age takes its toll.

73

 

[NightThumper]

Thanks for the input everyone. Radio is on the bench. Just need to take some pictures, warm up the Hakko, make a parts list and get to work...but not before a Labor Day Barbecue with friends.

 

[nomadradio]

Just don't install any of the electrolytics backwards.

Yeah, sounds simple, but it matters. I'm a witness.

Pulling out one at a time to then insert the next replacement is safer than removing them all at once. Helps to make sure the correct part goes in. May seem slower than simply removing them all at once.

Maybe, but it's safer.

73

 

[grimace]

some board can be market wrong like + should be - or - should be + look at the cap before you take it out

 

[nomadradio]

That's one good reason. The direction you found the cap turned is the right way, no matter if the screen-print legend on the circuit board says to install it the other way.

Good point.

This is another thing that can confuse a newcomer. The capacitors are nearly all marked with the negative end, a "-" in some form.

But the circuit board screen legend usually marks the "+" side. Just gotta put the lead marked negative in the 'other' hole. The one that's NOT marked "+".

Gotta wonder where that tradition comes from.

The radial-style caps also have one lead longer than the other. The long one is positive.

73

 

[NightThumper]

Thinking about just selling it as is with the SBE desk mic. This would be the 3rd radio I’ve re-capped in a month and my heart just isn’t into re-capping another one. I hate re-capping radios...yuk.

 

[guitar_199]

I'm about to order my caps for mine. I think my count is about 51 electrolytic caps and maybe 8 or 10 tantalums... something close to that. Does look like a LOT of work but worth it to me.

 

[guitar_199]

NT,

Did you ever make a call as to what you were going to do with this Console V?

I just found this old post and JUST this last Saturday (9/26/2020) started my recap on my own Console V. This is actually my first recap of a sideband radio and, while it is the same work as an AM, it is a lot more complex on the inside layout. for that reason.... I am taking it slow and easy.

But I did just see this and wondered what became of your effort?

I have high hopes for this one!!!!

Thanks,
Bob

Thinking about just selling it as is with the SBE desk mic. This would be the 3rd radio I’ve re-capped in a month and my heart just isn’t into re-capping another one. I hate re-capping radios...yuk.

 

[NightThumper]

Bob
It was a great radio when working. I didn’t have the time or inclination to re-cap it as I was working on three other radios at the time. I made a few inquires but no one who seemed interested in taking the job. I ended up mounting it in the way HomerBB(I think that’s right) did with his 980. Sent to the landfill

I saw your post and thought to bad I didn’t still have it, we could have compared notes or I could have given it to you for parts.

Good luck on your endeavors.

Brad

 

[guitar_199]

I'm sorry to hear it went that way but understand completely.

I have my original PLUS a very kind member on another forum found that I was working on mine and did exactly what you said..... GAVE me a unit he just had sitting aside...and thought he would never get to. I paid shipping and it is in a box under my bench here. Lucky for me as, I like my chassis better where his has a few bumps on it BUT his enclosure is in excellent shape where mine has some dings on it. I think it will turn out fine.

Thank you for your response.
73 and good luck down the road!

Bob

Bob
It was a great radio when working. I didn’t have the time or inclination to re-cap it as I was working on three other radios at the time. I made a few inquires but no one who seemed interested in taking the job. I ended up mounting it in the way HomerBB(I think that’s right) did with his 980. Sent to the landfill

I saw your post and thought to bad I didn’t still have it, we could have compared notes or I could have given it to you for parts.

Good luck on your endeavors.

Brad

 

[Slowmover]

See? Friends.

Connectin-the-bones.

Now, . . . if you can make the soldering iron work in time to Harry James

 

[radioreddz]

There was the same instance on Mikes cb repair Youtube page go there and search thru it he actually pirated some part from a Cobra MC 75 mic to fix it you may have the same problem search his Youtube post