Two Questions: 142GTL, 29/w RFX75

[CarolinaChuck]

Turned on the 142 the other day and the channel light started to dim followed by a cloud of smoke before it shut off. Before I open the case, does anyone want to take a stab at what I might what to look at?

A friend I worked with left and I pulled his radio out of the truck he was in. I called him up to get it back to him and he said he left it for me, says he has two more of them. My question is, there was a fuse holder on both the positive and negative power leads-don't ask me why. I left the harness in the truck as I may get around to sticking a radio back in it.

As I recall a standard Cobra 29 uses a 2 amp fuse, but what will a 29 with the RFX75 draw? As I recall the power consumption on my Magnum S-9 is 7 amps.

CC

 

[Klondike Mike]

Turned on the 142 the other day and the channel light started to dim followed by a cloud of smoke before it shut off. Before I open the case, does anyone want to take a stab at what I might what to look at?

My first guess would be the large electrolytic capacitor in the power supply section blew up. 40 year old caps will do that. Left hand side when viewing from the front.

 

[2RT307]

The dual fuse setup is to help with reversed polarity mistakes. Just in case you hook it up backwards, the fuse blows before your rig does. Nice preventative thing to do.

As far as the RFX-75, I'm thinking 10 amp fuse is correct.

73,
Brett

 

[CarolinaChuck]

Klondike Mike,

I was hoping someone would say something simple; I don't think I'll have much of a problem finding a bad cap as it smoked pretty good. What is it like getting at said mentioned cap to replace it? I don't feel like learning how to rip a 142 apart to get at this animal.

I'll tell you a funny story Mike. A long, long time ago in a Galaxy far away I was a radio repairmen in the Corps. My last duty station was aboard a Gator Freighter in the US Navy which had some gear on it we used and I was trained on in the Corps. Now, The Marines didn't own any of this gear on this ship, or any ship in the fleet for that mater; not our head trip, but from time to time I would help the guys with their gear. I did love the ride though...

Radio repairmen in the Corps were appliance changers. If a radio is broke you replace it and do the paperwork and send it off to "Float" and get another one back. Easy deal. At "float" you would replace the bad module and put it back into "float." Easy deal. On a Navy ship your at float out on the high seas, different story; no port-no "float" as a Marine would know it. They had parts in stock though like I had never seen.

We are out at sea, and out of boredom, I am playing with a bad radio the Navy techs were not trained on with a bad power supply. I am in a place no repairman should be and touch the 900V DC side of this power module and it lights me up, it hurt; I shook till after lunch.

Woo... Wooo....

Them Bloody Swabbies sure got a kick out of it! God I loved them boys, a no more bunch of particle jokers you'll ever fine. Don't tell Em, but they ain't much worth a piss in a fight individually, but as a whole they don't give up. I would sail with them any day, anywhere, to the ends of the Earth. Men, all of them.

R2T3,

I am thinking down the same road, and thought I would ask why I was at it. Although, the dual fuse thingy is probably not going to save much behind it as far as an Oops in cross polarity. It draws 10 amps?

What do I know? I am asking the questions here?

On to the next Caper,
CC

 

[ExitThirteen]

Hey CC, when the 142 base smoked and went dead, did you hear a hissing noise or a loud "bang" before it went black?


~Cheers~

 

[space cowboy]

the 142 is fairly easy to recap. you can replace them all without removing anything except the case and the capacitors. the hardest part for me was making sure I was unsoldering the correct components in the crowded sections of the main board.

I'd also recommend getting the caps from Klondike Mike if he's still selling them. all the caps and some pdf files of the board to help with placement. your main concern is a decent solder job and making sure the polarity is correct.

 

[Robb]

 

[space cowboy]

uh... there was no explosion.
exploding caps actually do explode, flying shrapnel and a fairly loud bang. that was just a cap frying.

 

[CarolinaChuck]

Exit,

Something made me look back at the channel indicator; the TV was on as the CB gear is out in the main room. It could vary well have been a cap leaking: I though I was hearing an an almost inaudible sizzle. When I turned it on it , the speaker did its crack thing and the indicator went on full glow; the radio came on.

Space,

You definitely need a nick name; I'll have to think about that...
Nice to know getting at the caps wont be a pain, but the idea of a complete cap replacement sounds both good and bad. I don't want to align the thing as I don't have the gear, nor have been trained on it. Also think that most of my board work was back on old Collins radio gear, or gear post of that era. I have actually seen wire-rapped components on posts...

I might have to rethink the whole thing. I guess I'll will just have to pull the cover off it and see what I see. Son, I ain't put an iron to a PC board in 30 years, or bought an iron for that matter since then; hell, I still got a tin of soldering paste I still use from when I left The Corps.

I'll have to let this thread soak a minute.

This Caper sounds like its Back-On!
CarolinaChuck

 

[space cowboy]

you don't need to align it after a recap. maybe it someone re-aligned it to compensate for the bad caps...
otherwise, swap-n-go.

 

[Klondike Mike]

... I'd also recommend getting the caps from Klondike Mike if he's still selling them. all the caps and some pdf files of the board to help with placement.

Thanks for the reference space cowboy. Yes, I still sell the kits. See link below for eBay listing but do not buy from there. I offer a $1.00 discount for all worldwidedx members for all of my kits. Send me a PM for details.

http://www.ebay.com/itm/Electrolyti...-PC-385-/142009620426?ssPageName=STRK:MESE:IT