29 WX NW ST No TX and No RX; Need Help Please

[Robb]

Was this a normally working radio that suddenly went <poof> all at once?
Or are you just fixing a radio that you picked up at a garage sale with unknown problems?
Just curious . . .

 

[LeapFrog]

Was this a normally working radio that suddenly went <poof> all at once?
Or are you just fixing a radio that you picked up at a garage sale with unknown problems?
Just curious . . .

I have had this radio for over a year, over the course of that year I have modified it, broken it and then fixed it several times.

The radio was working good when I put it up, and yesterday was the first time I've ran it in about 3 months.
While listening this problem just came about <poof> at once, I must say the power balance between channels was off! (so it is not a factory alignment, not stock driver/final PA configuration) I was poking and prodding the h3ll out this radio!

I will check TR23 voltages as the issue occurs, I have a feeling the problem will present itself again; I will get a chance to look into it today!

 

[BuckSkin]

check the voltages on TR23 in both receive and transmit. TR23 will be larger than the others on the board and looks about like the driver and final transistors.
post your findings.
LC

Okay........,
I could not find a TR23; however, I did find a W23 which looks like a bigger version of the two that are bolted onto that metal "wall" in the back corner.
With the radio upside-down, control knobs facing me, this W23 is located on the right-hand side, just ahead of the mounting bracket screw-hole, and about 1-1/4" in from the side.
Although this W23 has the metal mounting "plate" with bolt-hole, it is not bolted to anything.

This is how I checked voltage at W23: radio ON, DVM on 20v (or less) DC setting, black/ground cable clipped to the radio's grounded metal perimeter, touching each prong of W23 with the red cable probe.

Before I keyed the mike, the voltage reading at any of the three points would begin at around 9.5 to 10 and immediately start falling, with no definite voltage reading, as it constantly was dropping.

Once I had keyed the mike, readings were more stable.
The B pin held pretty steady at 6.28 whether the mike was keyed or not.
The C pin no mike keyed was 9.09; mike keyed was 8.33.
The E pin no mike keyed was 8.17; mike keyed was 7.61

Did I test the right thing and did I do the test right ?

Another thing I noticed when I had my ear very close to the radio: with the radio ON, as it would be for receiving, there is the faintest constant "ssshhhhhhh" coming from the speaker; I key the mike and it goes silent; release the mike and there is the little blip of static and the faint "sssshhhhhh" returns; this is so quiet that I just barely hear it.

Should I obtain some de-soldering wick before I proceed with the other tests ?

Thanks.

 

[9C1Driver]

I have had this radio for over a year, over the course of that year I have modified it, broken it and then fixed it several times.

The radio was working good when I put it up, and yesterday was the first time I've ran it in about 3 months.
While listening this problem just came about <poof> at once, I must say the power balance between channels was off! (so it is not a factory alignment, not stock driver/final PA configuration) I was poking and prodding the h3ll out this radio!

I will check TR23 voltages as the issue occurs, I have a feeling the problem will present itself again; I will get a chance to look into it today!

Sounds like a fun radio for you to mess around with. Don't put much money into it because it's not worth it. It would not be worth sending out for a repair either. The soundtracker radio's are probably the worst 25/29's ever built. Hence the nickname they earned, Soundcrappers.

 

[Robb]

Sounds like a fun radio for you to mess around with. Don't put much money into it because it's not worth it. It would not be worth sending out for a repair either. The soundtracker radio's are probably the worst 25/29's ever built. Hence the nickname they earned, Soundcrappers.

Yeah; but the soundtracker can so easily be disabled and is no longer an issue. Just have to lift two parts off of that board - is all . . .

 

[loosecannon]

ADDED MESSAGE: just read your last paragraph and need you to do a couple of easy tests.
with the broken radio set up like this: NB/ANL off, squelch all the way down, volume all the way UP, sound tracker and weather radio off, RF gain all the way UP, mic plugged in, antenna connected.

with your ear against the speaker (so you can hear the slight hiss) turn the squelch up while listening closely.
Did the sound change at some point in the squelch's range, or did it not change a damn thing?
put the squelch back all the way down.

next do the same with the RF gain. starting with it all the way up, ear against the speaker in the quietest room you have LOL, start turning the RF gain down.
did the hiss seem to lessen as the RF gain was turned down or did it not change a damn thing?






Buckskin, W23 is the right part (not sure why the heck they used a 'W' though!)

however, many CB radios (yours being one of them) have what is known as an isolated DC ground, which means that the ground on the PC board is isolated from the chassis (metal case) ground.

they are connected, but it's done through capacitors, and capacitors DO pass AC current (like the RF currents in your radio) but DO NOT pass DC current.

so, connecting your negative probe to the chassis is not going to get you an accurate DC measurement.

you will want to touch the negative probe to any of the metal cans you see on the PC board. each of these cans is a shield that covers a tuning coil, and these shields are all soldered to the DC ground plane on the PC board.

so, try the test again and post the results.

also, while you only want to do one test at a time, there really isn't a first second third type of relationship here because honestly i'm guessing and hoping that one of your tests will shine a light on your problem.

so you can test the voltages on the transistor first, then unsolder the driver and final leads, and while they are still unsoldered from the board (don't resolder them back in place until after you post the results of your tests on them) you can also unsolder one lead of D1, D2, and D3, and test them.

we are really shotgunning here, and if anyone has a more logical method that i am missing, please feel free to chime in.
LC

PS- yes, get some de-soldering braid, but don't bother buying it from a radio shack if you still have any in your area. it is useless.

 

[BuckSkin]

with your ear against the speaker (so you can hear the slight hiss) turn the squelch up while listening closely.
Did the sound change at some point in the squelch's range, or did it not change a damn thing?
When the squelch is at about the halfway point of it's rotation, the speaker goes silent, and it seems to do so abruptly, rather than tapering off; there is a definite point in the rotation where the hiss is either there or gone.

next do the same with the RF gain.

Turning the RF gain does nothing that I can hear; I tried it with the squelch all the way up and all the way down.

you will want to touch the negative probe to any of the metal cans you see on the PC board. each of these cans is a shield that covers a tuning coil, and these shields are all soldered to the DC ground plane on the PC board.

so, try the test again and post the results.

See my notes above in red.

By "metal cans", I hope you were meaning the little square metal boxes that each have a hole in the top with a visible plastic screw-driver slot in the hole, not much bigger than a sugar cube.

B: no mike = 8.60 --- mike keyed = 8.59

C: no mike = 11.42 --- mike keyed = 10.64

E: no mike = 7.96 --- mike keyed = 7.93

These readings were steady and several checks yielded consistent readings.

I will have to order the de-soldering wick/braid and it will take a few days to get here.

I really appreciate you taking the time to assist/educate me.

 

[loosecannon]

ok, sounds like squelch is working. good.

same test set up, but now measure the DC voltage on both sides of the ON/OFF switch. (on volume pot)
with the switch on, you should read the same voltage on either side of that switch.
what is that voltage?

after doing that test, unsolder the leads of the driver and final transistors from the PC board as previously instructed, and measure the DC voltages on W23 just like you did before.
did the voltage on the Collector change?

the voltage drop on the Collector of W23 is concerning, and might mean a short somewhere.
LC

 

[Robb]

Yeah if you like solder braid; then that is fine. IMO - it takes longer to heat up the wick and the joint in question. Ever try a suction tool? I recommend the kind that only takes one hand to operate so the other hand is holding the iron. Goes faster because the joint heats up faster.

 

[loosecannon]

Yeah if you like solder braid; then that is fine. IMO - it takes longer to heat up the wick and the joint in question. Ever try a suction tool? I recommend the kind that only takes one hand to operate so the other hand is holding the iron. Goes faster because the joint heats up faster.

Robb, if you get good quality solder braid that has the flux impregnated on it, it is just as fast, and cleaner than the solder bulb method. (IMO of course!)

I cant imagine trying to do a re-cap with a solder bulb. yeesh!
LC

 

[wavrider]

LC do you have an online source for ordering the flux impregnated solder wick? I would like to purchase some of the good stuff thanks.

 

[BuckSkin]

LC do you have an online source for ordering the flux impregnated solder wick? I would like to purchase some of the good stuff thanks.

I hope it is okay to post a link.

I just ordered this same stuff from E-bay (Ebay cost a few cents more, but I didn't have to spend $25 and wait an extra week or so):

Amazon product ASIN B00424S2C8
I looked at several brands and this stuff seemed to have the best recommendation from people who seemed to know what they were talking about.

MG Chemicals #3 No Clean Super Wick Desoldering Braid, 0.075" Width x 5' Length, Green

 

[BuckSkin]

same test set up, but now measure the DC voltage on both sides of the ON/OFF switch. (on volume pot)
with the switch on, you should read the same voltage on either side of that switch.
what is that voltage?
LC

Switch OFF: HOT side = 12.76v COLD side = 0.02
Switch ON: Both sides = 12.46v

My desoldering wick/braid is on the way; as soon as it gets here, I will do the tests that require desoldering.

 

[loosecannon]

good news on the switch.

I don't like that your supply voltage is less than 13.8 volts, but 12.5 volts in should be enough.

as for the solder braid, the "no clean" part means that it doesn't have a bunch of rosin on it that might need to be cleaned off later (IE wiped off with alcohol).

here is the stuff that i recommend, although what you ordered will probably work, you will just need a hotter temperature and may need to hold the iron on longer.

http://www.mpja.com/Superwick-426-Solder-braid-5ft-X10in-MG-Chemical/productinfo/30371+MG/

that is catalog #426 which is a 5 foot length of it.
I order #444 which is a 25 foot piece.

I would practice a bit on a junker radio so you know what to expect and won't be overheating traces. (PRO TIP- those copper pot scrubber things make great soldering iron tip cleaners)

i will check back with the thread after you get your wick.
if you post and don't hear from me within a couple of days, please feel free to PM me here on the forum.
LC

 

[LeapFrog]

Gentlemen, I worked on my E.F. Johnson Messenger Two yesterday replacing caps and I meant to post here but it never sent?

Anyway, today was a "day off" for me, I will probably be looking at the problem 29 in the next day or so, sorry I couldn't contribute anything important at this time.

All the Best