2000 problems Cobra down

[Bushwhacker]

Hello first post, I have plenty of gear and no idea! With that said I have a few cobra 2000’s 3 actually. all with similar problems. So I’m starting with the one I paid the least for $140. Came with the toggles snapped off. I was able to snag some replacement unit and after finding the rats nest of wires I just changed the switches themselves
It came doa and after a quick look found the power switch in the back 120/12v was pushed in and lucky for me all the parts were floating around inside. I was happy to see some life.
The radio is in great shape as I have seen some really bad golden screwdriver cobras and I must say it hurts. Looks like my cobra 2000 # 3 has the headphones Jack strip tied inside and the 2 crystals added for channels, easy to remove like it so far.
Radio came on never got tx/rx but the counter worked for a few then went to 32.424 something like that
So now it’s static on ssb but dead am.
I ordered the cap kit from Klondike like $30
And blindly ordered some chips tc5032. Ta7222. mb3756. Nothing out the pa speaker. Started to clean it a little
Any help getting #3 up with really be appreciated I don’t have Carlsons lab over here, but I do have a lot of equipment I acquired slowly. not that I know how to use it. Few o-scopes some old signal stuff that I need to get working tube testers as well and I apologize for not knowing exactly what I’m doing

 

[Bushwhacker]

I think with a little help (hint hint) I can get this old girl back up and running.
Just waiting for some parts.
This definitely will take huge time, I know it’s going to need heat sink compound on everything as it looks a little dry. New caps and a few hours of work.
Was hoping to get some pointers and guidance. Just seems the info is out there just all over the place. Feel free to jump in here with some ideas

 

[nomadradio]

Age and mileage both serve to suggest where you look first. The very-oldest Taiwan radio from 1979 has a longer list of likely failures to choose from than the 1993 Philippines radio.

The older the radio, the more important it can be to get a proper control cleaner/lube into the mode selector. If it gets crusty enough, nothing works.

If there is no audio at all, my go-to Swiss-army knife is a 'scope. Probe pin 9 of the TA7222P audio power chip. Should have a DC voltage very nearly one-half the DC supply voltage at pin 1. Connect an antenna, turn up the RF Gain and volume. If the meter isn't stuck, and you see movement, turning up the volume should get you the audio waveform on pin 9. Any problem hearing the receiver from this starting point lies with the headphone jack, receive side of the mike, or the front-panel speaker selector. And if you don't have a 'scope, a DC meter on pin 9 will at least reveal if it's close to the half of pin 1 voltage rule.

Troubleshooting starts with identifying which circuit elements are working, Eventually you'll find what isn't.

Of course, you can just use the "Manual Digital Signal Injector". Lay your index finger alongside the metal shaft of a small screwdriver. Touch it to pin 4 of the TA7222P audio power chip. If you hear a raucous hum, the receive trouble is upstream from there. Touching it to the center pin of the volume control with the control turned full up should also get you a hum.

If you do, next try the squelch knob. The squelch circuit should produce a small "thump" in the speaker when turned quickly end-to-end.

The result of the S-meter check and the steps above will determine what to look at next.

73

 

[Bushwhacker]

Yes this is the early Taiwan version, I hear static so there is some audio. I used a 40 channel walkie-talkie and can’t pickup the signal. Meters work good on this one. Othe two not so much. I did see Mike’s video on adjusting them though. Got a good look at the 7222 which is not that easy with things packed tight in the way, but I do have one on the way just in case. Will like to pull it to clean of the old compound and I’ll get a reading. I have the rigol

And a nice Tektronix

I’ll check that voltage though sounds like the best place to start. I’m sure it’s my fault I could have use my variac and brought this up slow. I’m just to anxious at times. Hope to recap her and then get a good feel for what is out of whack. After the ne capacitors are in.