Galaxy 44v diode?

[Eldorado828]

So I've got a 44v here that I'm putting back together after a hack go ahold of it.... Imagine that right? OK well on the back of the am/fm/pa rotary switch there's a diode that goes from pins 3/2 back over to pin 1 with the banded end on pins 2/3. There was only a piece left of it and a disconnected yellow wire that goes back to the echo pcb. Question I have is what is that diode supposed to be? I've looked over at cbt and it's nowhere on the parts list so I'm at a stand still on that part of it. Wondering if anyone might be able to help me out on what that's supposed to be. What's left of the diode is illegible and my eyes with readers and magnifier just can't make what's left haha. I appreciate it in advance

 

[999]

There is no indication that it should have been there from this:

http://www.cbtricks.com/radios/galaxy/dx44v/graphics/dx44v_inter_wiring.pdf

 

[Eldorado828]

There is no indication that it should have been there from this:

http://www.cbtricks.com/radios/galaxy/dx44v/graphics/dx44v_inter_wiring.pdf

That's what complicates it. Working on 1 or 2 in the past I remember replacing the switch and just using the same diode from the donor turned out OK. Thing is that I don't remember looking to see what the diode was

 

[NZ8N]

1N4148. That goes in the PTT line from the Mic to the Echo Board, and it is not on either schematic diagram, the B (early) or the C (later). The schematics show 2 sections on the switch with a jumper to adjacent pins, the PTT section, and the speaker ground/PA switch ground, which would not need a diode.. It is not in the interconnect diagram, as 1,2,3 and 4 are empty on that. The banded end (Cathode) goes towards the PTT input of the Echo Board so it can key the radio, but in PA mode, it doesn't key the radio.

 

[Eldorado828]

That's what I'd assumed it was so with you verifying that I'm going to run with it.

 

[Eldorado828]

Now it's undoing everything that's been done... Removed diode resistor and put back to original r239, installed tr32 because it was missing of course. Dual Mosfets but the modification looks done correctly as far as I can tell so far all the values are correct and solder work looks good too. Hopefully I'll have a chance to get it powered up tonight and see how it does. I appreciate the help so far fellas!

 

[Handy Andy]

Keep Us Posted!

 

[Eldorado828]

Finally got back to the 44 and put some voltage to it. Mostly everything seems to be working like it should other than the echo pcb. Without it, audio is nice and clear through my monitor radio and through the talkback. Turning it on turns into a different story. A high pitch noise almost like a whistle with the echo volume up anything past 12 o'clock. The delay is inconsistent as far as staying at one level of delay as well. I'll start looking for bad caps and solder pads now to see where that leads me. It almost seems like a ground loop issue but we'll see where the chase goes. I'm open for hints!

 

[Eldorado828]

Does anyone have one of these boards and willing to part with it?

 

[Handy Andy]

The things are old, so would a recapping of that little board help?

 

[TheRealPorkchop]

Does anyone have one of these boards and willing to part with it?

The noise you’re talking about seems common with those things. Seen it hundreds of times. I probably have a 5 gallon bucket full of those things but I can’t guarantee their condition.

You May be better off doing what I do, toss them in a 5 gallon bucket and install a new one. But I’ll gather you up one or two if you really want to try one.

 

[Eldorado828]

Well fellas I've finally got an update. Thanks Andy, I replaced all the electrolytic and mica caps on the board and it really seemed to straighten it out but like realporkchop said, even though it sounds ok the board is just noisy when turned on. I guess I've never noticed one of these older rigs having a noisy TX with echo like this one. Realporkchop, thanks for the offer bro I just almost took you up on it and I would have if this thing didn't pan out. Much appreciated

 

[TheRealPorkchop]

No problem, you’re welcome. Glad you got it sorted as best you did.

 

[Robb]

Well fellas I've finally got an update. Thanks Andy, I replaced all the electrolytic and mica caps on the board and it really seemed to straighten it out but like realporkchop said, even though it sounds ok the board is just noisy when turned on. I guess I've never noticed one of these older rigs having a noisy TX with echo like this one. Realporkchop, thanks for the offer bro I just almost took you up on it and I would have if this thing didn't pan out. Much appreciated

If you are going to take it any further, then you might also check resistors for being out of tolerance too. These may contribute noise. Likewise testing transistors for leakage (low hfE) and diodes for leakage too.

 

[Handy Andy]

They have those "controls and headers" connector issues too, dirt gets into the knob and switch, making it sound scratchy - best to just give it a shot of a simple tuner cleaner.

If you remember the Mongoose or even the Detta-Force early vintage models? Uses headers - similar setup - you switched around headers and the Echo worked - but the knobs went back to the board, not the main PCB - which generates it's own issues. So even a cleanup - burnish of the side panel to right-angle bracket to board mounting flange may be needed. If you'll note in your echo photo - you have "press inserts" even for the clamshells - so the Oxides of March are upon you...Happens every season...

I actually liked the echo in this board - but the age is usually what kills the fun of even using it - when it's old - it is old - and sounds like it - which, sadly a little effort in clean up is not what too many have the patience for.