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Surgeon needed for RM Italy KL503HD

Is there a recommended wire solder type and diameter that is best used when doing mosfet replacements? I have a bunch of bars like this in my workshop but I think they may be a bit unwieldy. :)

1674742471743.png
 
I have started my attempt at repairing the amp by removing the driver mosfet and am testing it out. The pictures below show how I have oriented the mosfet and which pin I think is which. I am following this video's instructions to test it.

1. Put fingers on G, D, S to turn mosfet to off state.

2. Test off state:
S: Black lead
D: Red lead

My reading is 0, so no continuity which is good. If reading was > 0, mosfet is bad.

3. Turn on mosfet:
S: Black lead
G: Red lead

Hold for five seconds, my meter remained at 0, sounds right.

4. Check if mosfet is now on:
S: Black lead
D: Red lead

My reading is still 0 but is supposed to be > 0 to indicate the mosfet is turned on. Bad mosfet?

5. Turn off mosfet:
Finger on G and S for several seconds.

6. Confirm mosfet is off:
S: Black lead
D: Red lead

My reading remains at 0.

Does step 4 indicate the driver mosfet is kaput? I want to make sure I understand the proper diagnostic steps before diving into the other eight mosfets.

Mosfet1 - Copy.jpg
Mosfet2 - Copy.jpg
TestMeter - Copy.jpg
 
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I finished removing the rest of the mosfets and tested them the same way I did the driver. The driver is the only one that failed step 4. The rest turned on/off the way it was described in the video.

I ordered the replacements on Wednesday and they are supposed to be here today. However, I really don't think that is going to happen because the FedEx shipping status is still just at the label created stage and the order itself is still sitting in Minnesota. Oh well.

I did make one mistake I am aware of so far in this repair. When I was removing the circuit board I missed a screw that looks like it was for grounding the board to the case. @#$#@.

Capture.JPG
Capture.JPG
 
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Your trouble shooting looks correct. I would expect a good one to show continuity one way or the other. But you got a reading of wide open no matter which way you did it. I am not sure what the 7db component left on the heat sink would be. Almost makes me think of a temperature switch the way it is mounted. But then 7db doesn't make sense.

Do you plan on bypassing the driver?
 
Your trouble shooting looks correct. I would expect a good one to show continuity one way or the other. But you got a reading of wide open no matter which way you did it. I am not sure what the 7db component left on the heat sink would be. Almost makes me think of a temperature switch the way it is mounted. But then 7db doesn't make sense.

Do you plan on bypassing the driver?
I've been searching the web to try to find a picture of how that 7db component actually connects to the two ends that I broke off. Bound to be a picture out there somewhere.

I did start doing some searching on here about bypassing the driver but ended up getting dragged away by that great interrupter... my job. I'm hoping to have some time to continue the research and learning on the bypass tomorrow afternoon.
It sounds like if I just stick to using the President Lincoln II+ at a lower PEP than the Q5N2 is blasting at the amp, the amp would be okay. I sure hope it works after this repair. If not, it's still another good step on my learning curve (positive spin). I must admit I much prefer the steps are not so costly.

Transceivers don't kill amps, people misusing transceivers kill amps. Or something like that.
 
I've been searching the web to try to find a picture of how that 7db component actually connects to the two ends that I broke off. Bound to be a picture out there somewhere.

I did start doing some searching on here about bypassing the driver but ended up getting dragged away by that great interrupter... my job. I'm hoping to have some time to continue the research and learning on the bypass tomorrow afternoon.
It sounds like if I just stick to using the President Lincoln II+ at a lower PEP than the Q5N2 is blasting at the amp, the amp would be okay. I sure hope it works after this repair. If not, it's still another good step on my learning curve (positive spin). I must admit I much prefer the steps are not so costly.

Transceivers don't kill amps, people misusing transceivers kill amps. Or something like that.
I think the Q5n2 will be ok with the driver bypassed, maybe someone who has done the modification can verify.
 
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