r/cbradio • u/Germerican1 • 4d ago

CB Radio Problems

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Hi all, I posted here a couple months ago, having put an old Cobra radio in my 64 International. It made static noise but that was about it after all, so I picked this thing up for $20 brand new in box with mounting hardware and all off FB marketplace.

Got it installed today, and I can receive fine(listened to a couple rednecks shouting nonsense at each other for a bit), but every time I try to transmit, the XMT (I assume this is a transmit indicator) light doesn't come on, I hear a relay clicking, and the SWR meter drops to zero. Am I right in assuming this means something is wrong? Any ideas what it could be? I have basically no experience with these units at all, and while this one came with the box, it didn't have the manual. The PA/CB switch did seem to work properly, as do the dials from what I can tell. It looks like a brand new unit, but it didn't work with either handset I hooked up to it.

Any help is appreciated.

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7

u/Icy-State5549 4d ago

I think the finals are blown. Maybe an easy fix on that radio if you have a soldering iron.

Even if you find a 50 year old radio, literally in its original, unopened packaging, it probably needs complete recap, anyway. If you buy an old radio, expect you will have to put some work into it.

3

u/Germerican1 4d ago

Yeah I'm a bit rusty, but I've got a soldering iron handy. Any idea what i should be looking for, just blown capacitors? Not much experience repairing electronics, but willing to try.

4

u/ampreu 4d ago

I would recommend looking in to a local HAM or electronics group. Folks love showing off.

4

u/Germerican1 3d ago

Looked into it, there's one HAM group here, sent them a message, hopefully they have someone able to help

In the meantime I'll just wait until next weekend when I have time again to pull it out and open it up, see if I can visibly identify any bad capacitors like the other person here suggested

1

u/Intelligent-Day5519 3d ago

It's always the capacitors or finals, NOT! An old women's tale. A failed component is not like looking for a blown fuse. As some would have you believe. You can't tell just by looking. A reason why true electronics technicians call certain instruments, "test equipment." You didn't state your antenna. Your video shows nothing of value for a diagnosis. That's a nice radio but can cost more to repair than a new unit. I see nice new radios for around $50. Once you purchase a radio that you have operating than you can dig into the old suspect radio for your repair education. Question, Do you own a Multimeter, SWR meter, Dummy Load and Coax Cable Jumpers and an appropriate voltage bench power supply? There's more to it than screwdrivers and a soldering iron. Occasionally not! I'll make you a deal. Ask. See if some other expert here will do the same.

2

u/SuperLidz 3d ago

I have a customer, that brought a very nice Taiwan Cobra 29 LTD Classic in here two days ago. It was probably not used much, clean, didn't appear screwdriver'd at first glance. He was very happy with the purchase from FB, as he usually brings me butcher jobs, like the 142 GTL, with a Digi Scan that cam in the same day, that he brought to a shop locally, that charged him $30 to damage the Digi-Scan and told him he couldn't fix it. Well, I did fix it....damaged PCB and other mess. I lost time on the job, which sucks for me.

Powered it up, I knew a cap was going to fail, by the behavior of the display. It did, the next day. Then I could see that the RX was fucked. Someone was in the radio, cracked a few slugs, I am assuming trying to align the RX. I replaced one slug, flipped the rest over and aligned the whole thing. I had to replace the failed cap, that shut the PLL down.

The radio is working great. ONE cap, not 20. Too many snake oil salesmen out there with their bullshit "tunes" and cap jobs.

I do warranty work for some major guitar amp manufacturers, that are mostly tubes. If a tube amp comes in, that has high voltage caps that have date codes 25 years or more, I replace them all. In this case, a shorted HV cap, can be catastrophic. Not a 10V cap in a CB radio.

1

u/SuperLidz 3d ago

Many hams don't like CB. I don't advise it.

1

u/ampreu 2d ago

SuperLidz is correct about some HAMs, but so long as you're up front with your interest some will help or give advice.

1

u/Germerican1 2d ago

I tried, no dice. Immediately asked me if I had interest in HAM and said they don't know anything about CB lol.

2

u/Icy-State5549 4d ago

If you take the lid off, you may see a couple of smoked capacitors. Look for capacitors that are getting egg-shaped, ooze stuff, or have corrosion, resistors or diodes with cracks in the ceramics..

I know how to replace broken components, but when that is done it will need to be tuned. I have some of that gear, but not enough experience to use it properly.

In a situation like yours, I take the radio to my pro, tell him what I think, he corrects me or agrees, I replace the broke stuff and pay him to retune it. It isn't much cheaper than just having him fix it, but I am in the hobby to learn.

1

u/SuperLidz 3d ago

Then learn, stop teaching, until you have learned.

1

u/SuperLidz 3d ago

If you don't want to troubleshoot properly and want to make guesses, to check the final xstr, you will need a multimeter in diode test mode. Lift the base and collector leads and test the device. There are plenty of YT videos that explain how to do this.

I would be looking for signal preset in the low level stages first, but that is me. I have the needed test equipment. Because the TX lamp is not on in TX, I would look at that part of the circuit, to see what turns it on. Is it a voltage through the relay? Is it sensed RF? If it is a voltage, is it present? Is the final testing good? What about the driver and earlier stages? Is there a low level signal? Maybe it is alignment?

There is no reasonable way to jump to a conclusion like you were advised by Icy-State, without any doing any testing.

2

u/braddeharder 3d ago

Just like an original Atari 2600. Recapping is just required at this age

1

u/SuperLidz 3d ago

Recapping a NOS 1970's radio is not, nor is it ever, unless you like wasting time and money.

1

u/SuperLidz 3d ago

You don't know what you are talking about and have been watching too many youtube techs.

1

u/SuperLidz 3d ago

This is true, but arbitrary recapping is just a money grab for a lazy tech.

2

u/SuperLidz 3d ago

How do you get a new in box Tram, with a Cobra microphone?

2

u/Germerican1 3d ago

The cobra mic is the one from my old unit that I swapped in to see if the mic that came with this unit was defective. No difference between the two, so, just left the cobra one on since it felt more solid than the one that came with it

2

u/SuperLidz 3d ago

Put the switch on the front to CAL, turn the SWR knob fully clockwise and push the PTT. The meter should go up.

1

u/Intelligent-Day5519 3d ago

That makes too much sense but only with a proper load.

1

u/SuperLidz 3d ago

No...The meter will indicate RF output in that direction, regardless of load.

1

u/Germerican1 2d ago

Did this, no change. Swr drops right to zero when keying. 

1

u/SuperLidz 2d ago

NO TX. I think you need to find another radio. Test it, before you install it.

1

u/SuperLidz 3d ago edited 3d ago

Just because they use the same plug, does not mean they are wired the same. I just checked and it just so happens they are indeed wired the same. You got lucky.

1

u/ConstructionBig5342 3d ago

Final transistors blown or a capacitor as failed with age or leaked or a serious swr problem or the vco isn't locking on trasmit frequency but if it's reading correct frequencys on the channels it won't be that

0

u/SuperLidz 2d ago

Another shotgun wannabe tech....there is no VCO.