RCI-2980 Final Replacement

[Nomadd1776]

Got a RCI-2980 (non WX version) that a final blew on. Im planning on replacing both of them, along with the bias diodes, the 1w resistors and the pots. My question is about the MV1Y bias diodes. I have searched on here and other forums and not sure what way I should go. I have read that I can use 1n914's diodes, epoxied to the boards just like the MV1Y's are, and I have also read that I can use 1n4148's without them having to be on the boards. Will it make a difference in which ones I use? Is what I read correct and can I use either the 1n914's or the 1n4148's or should I try to find the MV1Y's? Thanks in advance for any advice.

 

[sp5it]

I use 1n4148, but must stick to transistor surface.
Mike

 

[Nomadd1776]

I use 1n4148, but must stick to transistor surface.
Mike

Should it be epoxied to the transistor or do you think thermal paste would be a better idea?

 

[sp5it]

I put a drop of the paste and bend legs of diode to make it stick to transistor.
Mike

 

[Nomadd1776]

Good deal. Thanks for the info. Ill post some pictures when I do the replacement aftet the finals get delivered. Thanks again.

 

[brandon7861]

I have SMD 1N4148's. I could make replacements that screw to the heat sync like the originals so the diode body is flush against the heat sync. I have no idea how they would perform compared to the originals, but that could easily be tested by bolting one next to an original and heating them together watching the VF with a scope on a long timebase. And I could borrow an original from my washington to do that.

I'll back-burner this thought unless someone says they want me to. Sounds fun though.

 

[brandon7861]

We are going to have cheap replacements for this part very soon. I just ordered 500 BAV99W's. I think I will sell pairs of them (on the PCB) for $5.

Since these are like the 3-terminal ones in my washington that have two diodes in them, they will be able to serve as a single junction MV1Y or a dual junction MV13YH by simply adding solder across two pads. I will pre-drill and etch a few dozen pieces this weekend while I wait for them to arrive.

edit: heres the plan. when I get them, I am going to monitor the bias current on my washington as it warms up. Ill key down into the dummy load for a specific time and watch the temp on the thermal camera. I can plot the bias current vs temp. Then I will put one of these diodes in and do the same and see if the bias remains acceptable over the same temp swing. I will probably have to readjust the bias for the new diodes, but I am guessing they will track the same. We are going to find out. I'll report my findings in a separate thread.