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QDX Toast for Breakfast #smoke #ibreakfast4mosfets #qdx

 

While you have the BS170s out, consider installing sockets.? Cut three pins off of a machine-pin DIP socket with a Dremel tool or a teeny tiny modeling saw.

For the 3 and 3A boards, you have to spread the two end pins out a little bit to get them into the holes in the PCB.? For 4 and later boards, the pin spacing is perfect.

73
Jim N6OTQ

On Fri, Nov 18, 2022 at 10:16 AM Rob - KC4NYK <rbt@...> wrote:

Questions questions.
1. Looks like I need to analyze that again and maybe check the finals although I don't have a clue how to do that. VOM? Can Q11 I test in-situ?
2. Would the software disconnecting have anything to do with toasty finals? (I'm running on an R-Pi but no problems the other 10 times I've used it)?
3. Anything else to check? - I have access to but no working knowledge of bench equipment - well rudimentary at best.
4. Would the lack of a final cause the entire board to go dark? No RX ? Etc.?

Other suggestions?
 

Has anyone done this? Doesn¡¯t it change capacitance and inductance values, and limit the use of the heat sink in a QMX+?
 

As a thermal analyst by trade I'm not a fan of sockets, for the reasons you state. Given that these are at least sort of pressed against the board to improve the heat removal the lead conduction is less important, but probably not nothing.

 

Once upon a time socketed semiconductor and SOT devices used to be very common. ?

Based on history in a test equipment repair dept ? large or fixed or multi pin thermally active (meaning pins/wires all moving in the socket or pins/wires moving differentially) ?devices in sockets were a sure place to look first for failures as microscopic lead movement led to bad contacts. ?
?
A huge proportion of failure stories after a couple of years were actually only bad sockets. ? Every manufacturer stopped using them in these scenarios?
?
Sockets have their places in many designs and for prototyping but I would never dream of using them in this BS170 scenario

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