Ranger RCI-69 (1st edition) blowing finals...

[Hawkeye351]

Got a Ranger RCI-69 (1st edition) on the desk today.

Reason for being on my desk:
Blowing finals not long after being replaced.

Evaluation:
The last final (RT1) shorted and next to last final (RT1) weakened, then popped.

I've replaced these mosfets once before about 2 months ago, then the user stated he had an issue with the input of his amp and it took out those new finals. I just replaced those mosfets again, keyed up for a brief second and pow, it blew the last final in the chain again. Each time I replace finals, I always reset the bias before testing it, as I did this time also. The bias sets great, but once you reattach the bias jumpers and key up, pow it blows a final, as if it sees an immediate high SWR, but my external meter shows a perfect SWR from my dummy load. When it blows a final, the radio immediately shuts off and the power supply won't come back on unless you unhook the DC supply feeding the main board.

Any advice guys/gals?

 

[brandon7861]

Dummy loads are non-reactive, so harmonics and other spurious emissions are all the same to the dummy load. It will absorb all of it without any reflection. To see no reflection (flat SWR) on a dummy load is expected.

Try the next batch of finals into a dummy load only (so there are no reflections to do damage) and have a look at the spectrum coming out. Any RF not on 27MHz will be bouncing back to the finals when the radio is connected to anything other than a dummy load. Maybe the harmonic trap is messed up or higher gain replacement parts are causing oscillations.

Edit: Should have asked first. Is it blowing on the dummy load too? Or just into a reactive load?

 

[Hawkeye351]

Dummy load, haven't tested on air yet. Checked my jumper also, no issues on my setup.

 

[brandon7861]

Check for continuity between the antenna jack and ground just to be sure none of the filter and matching caps shorted.

 

[brandon7861]

I don't have a schematic, using the dx55hp as a reference since it is dual final using 520's.

Another thing to check would be the zener diodes. They don't do much for biasing, they just protect the gate from higher voltage spikes. If somehow the driver or self-oscillation provides more than 20v to the gate, its toast (and I don't think it would even take that much since that datasheet spec is just for ESD or oops moments, not repeated spikes that turn it on hard over and over).

 

[Recon]

Got a Ranger RCI-69 (1st edition) on the desk today.

Reason for being on my desk:
Blowing finals not long after being replaced.

Evaluation:
The last final (RT1) shorted and next to last final (RT1) weakened, then popped.

I've replaced these mosfets once before about 2 months ago, then the user stated he had an issue with the input of his amp and it took out those new finals. I just replaced those mosfets again, keyed up for a brief second and pow, it blew the last final in the chain again. Each time I replace finals, I always reset the bias before testing it, as I did this time also. The bias sets great, but once you reattach the bias jumpers and key up, pow it blows a final, as if it sees an immediate high SWR, but my external meter shows a perfect SWR from my dummy load. When it blows a final, the radio immediately shuts off and the power supply won't come back on unless you unhook the DC supply feeding the main board.

Any advice guys/gals?

This is a photo of a bent board on a new out-of-the box Ranger made mobile radio. Should the radio be turned-on and used?

 

[Shadetree Mechanic]

This is a photo of a bent board on a new out-of-the box Ranger made mobile radio. Should the radio be turned-on and used?

Wow, how did they even get the screws in? Quality is in the dumpster, and it's a shame to see them going down hill. I really wish they could have Anytone build them a few radios....

 

[Recon]

Wow, how did they even get the screws in? Quality is in the dumpster, and it's a shame to see them going down hill. I really wish they could have Anytone build them a few radios....

And......the Authorized Repair Center's response was, "it will be OK".

 

[Shadetree Mechanic]

And......the Authorized Repair Center's response was, "it will be OK".

Wow, their response was "we are not going to make any money on this".... Buyer beware....

I would take the front screws out so the board can lay flat.

 

[Recon]

Wow, their response was "we are not going to make any money on this".... Buyer beware....

I would take the front screws out so the board can lay flat.

Oh yea, I forgot about the TDA2003.

 

[Recon]

Oh yea, I forgot about the TDA2003.

Removing the screws will not resolve the issue because the location / position of the "tab" is applying down-pressure on the board. The location of the hole for the tab is the cause of defect.

 

[brandon7861]

Can the holes be reamed out a little? Maybe a dremel using a carbide cutter? I've done that while Frankensteining two radios together.

 

[AudioShockwav]

And......the Authorized Repair Center's response was, "it will be OK".

I have to ask, was this Chris in CA?
I am gobsmacked by that bend in the board.

73
Jeff

 

[Recon]

Can the holes be reamed out a little? Maybe a dremel using a carbide cutter? I've done that while Frankensteining two radios together.
View attachment 70820

Yes, it is possible, but I don't have the radio. I am assuming this is not the first and only radio produced and released with a bent board because the hole was probably punched / drilled by an assembly line machine. The assembly line must continue to move, and installer of the board had no choice but to bend the circuit board to attach the tab. Is this another normal and acceptable practice? What is the longevity of a radio with a bent / distorted circuit board? It's just another example of Form, Fit and Function.

 

[Recon]

Wow, how did they even get the screws in? Quality is in the dumpster, and it's a shame to see them going down hill. I really wish they could have Anytone build them a few radios....

My guess is that the board was secured with the screws prior to connecting the tab and the board was bent down to attach the tab.