Dead DX2517

[TruckerKevin]

The bridge rectifier tested good. Your troubleshooting mini guide made sense to me and I understood how I could have been testing it improperly.

I printed out the schematic for the power supply Saturday morning so I could follow it with a small marker and began tracing the cause. I tested each diode, resistor and transistor and slowly followed the trace until I narrowed it down to the board losing power at the mentioned transistor. I discovered that voltage went it, but never came out. That is when I got curious and removed the transistor and tested it.

I suspect that I have an issue around D107 area of the board, or else the power supply board threw voltage to that area. Because when I acquired this radio, I found diode D-107 smoked, and a burn spot in that area. I replaced the diode, but the radio quit working minutes later.

But, since it is not powering on, I am limited to what I can do there. I might very well continue on with this thread.

 

[Ranch55]

Well sure. Let us know how you are progressing. You have some good help on this forum.

 

[kaos513]

I like this thread,like to see people help others i think kevin maybe very close.

 

[loosecannon]

TK, While you may have found a bad transistor, the new info you provided suggests to me that you may have another culprit.

When describing a problem to a tech, you want to include ALL the info you have even if you don't think it's relevant.

D107 being smoked is a big red flag!

have a look at the schematic and look at Q54, the 2SB754 (might be a 2SB827 in your radio) see how the emitter is tied right to the main voltage rail.

If this transistor is shorted, it could definitely take out D107 and pull the supply voltage right down to where the radio won't turn on.

remember that you CANNOT test a transistor while it is wired to anything.
EVERY time you want to test a transistor, you need to remove it from the board first.

this should be an easy concept to understand seeing the problem you just had with the bridge rectifier was solved by taking it out of circuit in order to get a correct test on it.

so, you need to remove that power supply transistor and test it out of circuit, then do the same for Q54 and the transistors surrounding it (Q55, Q57 etc...)

i have a hunch that you are going to find Q54 shorted and maybe some others, as i believe this radio might have suffered a catastrophic failure that might have taken out multiple parts.

if you are going to just try replacing transistors and turning it on with fingers crossed, be sure to replace the two fuses (external and internal) with 2 amp fuses.
the radio doesnt draw even 1 amp on receive so this will help save other components if you do indeed have a short somewhere else.

If the radio was here, i would disconnect the output of the power supply from the main PC board and any other outputs before replacing parts and testing it.
then i would get it working properly.
then i would test for shorts on the main voltage rail of the PC board to make sure it was safe to re-connect the power supply, again using small amperage fuses at first.

take it in stages, and replace one part at a time so you will know if you screw something up along the way.

good luck,
LC

 

[TruckerKevin]

Fixed

Although I am not positive I have it all cured (yet)

But the transistor was indeed bad

 

[TruckerKevin]

Okay, I know what was wrong with this. Really.

After I got it working, there was an intermittent short, the radio would shut off and back on. It acted like a cold solder joint.

I could press on the board and it would unsquelch and briefly shut off. I looked for the cold solder joint very carefully, but could never find it.

I found the corner of the board arching between the ground. It looked like it was losing ground. Upon close inspection, I saw the board actually cracked on the corner, like someone had pressed down on it. I’m not sure if the crack was the real culprit, but the arc shut her down again and blew the same transistor.

Fed up, I put it on eBay for parts, explained the board was bad and sold it within 30 minutes.

I’m just referencing what I went through in case any other google searches leads anybody to here.

 

[357magnum]

Hmmm ... That's another thread to start about radios and bad cold solder joints I myself have seen to much of this lately . I myself not a Big Fan of Galaxy's but before you all start I do own a 98V but seldom use it ! JMO 73 and God Bless , Let it roll I have big shoulder's.lol