If either #219 or #220 were in reply to my question to Logic800, I agree with what you're saying, separate from my question.
However, referencing back to Logic800's statement and my question...
My thought would be that it does not matter how the hole was tapped or who tapped the hole... if the premise was that the path of conduction is from the 'bare metal' in the heatsink (inside the hole) which is generally at mains earth potential... through the bolt... through the 'insulator' ... and to the drain of the device.
Now... those two things above could certainly provide other paths of conduction / bad things... but they are additional to what I(I think) Logic800 was trying to convey. Maybe they've got some additional thoughts.
However, referencing back to Logic800's statement and my question...
My thought would be that it does not matter how the hole was tapped or who tapped the hole... if the premise was that the path of conduction is from the 'bare metal' in the heatsink (inside the hole) which is generally at mains earth potential... through the bolt... through the 'insulator' ... and to the drain of the device.
Now... those two things above could certainly provide other paths of conduction / bad things... but they are additional to what I(I think) Logic800 was trying to convey. Maybe they've got some additional thoughts.
^ Now I'm following. THANKS! Really appreciate the clarification. I knew I was missing something in the train of thought.
However, the inside of the holes for the Modushop chassis are not anodized. Edited to add - or if they are, then it's still conductive... or the threads cut it... or ... or...
So, FWIW... I agree with the concerns overall re: contact with the bolt, and I just wanted to be sure folks didn't think that they were somehow immune to this with Modushop chassis.
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For all - FWIW, I learned from a wise man that is kind enough to post a lot around these parts that it's always a wise thing to check the resistance from the bolt head => inside the sink => mains earth to all three pins of the MOSFET before soldering the MOSFET into place. If it's not in the MOhm range, I start looking around.
@TungstenAudio ... I think I stole that from you ages ago when I was building my first amp. It's been in my startup process ever since.
However, the inside of the holes for the Modushop chassis are not anodized. Edited to add - or if they are, then it's still conductive... or the threads cut it... or ... or...
So, FWIW... I agree with the concerns overall re: contact with the bolt, and I just wanted to be sure folks didn't think that they were somehow immune to this with Modushop chassis.
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For all - FWIW, I learned from a wise man that is kind enough to post a lot around these parts that it's always a wise thing to check the resistance from the bolt head => inside the sink => mains earth to all three pins of the MOSFET before soldering the MOSFET into place. If it's not in the MOhm range, I start looking around.
@TungstenAudio ... I think I stole that from you ages ago when I was building my first amp. It's been in my startup process ever since.
Yep... that's why I had asked the follow-up.
If I got it correct, and if we agree...
Moral of the story (from my perspective) was and is... if you're gonna use those pads (or any other conductive pad), then it's best to absolutely ensure that there is no contact / no conductivity between the pad and anything that leads to mains earth potential (including the bolt) or anything other than where you'd like current to flow...
piece of cake
I'm so good at it, I can do it at distance ....... 1K2miles is doable
all I need is general area
Not expected as a problem as the transistor case has a 0.3" plastic insulating ring
around the mounting hole.
As long as the non-insulating pads don't touch the bolt, it should be fine to use them with a clean anodized heatsink. If you need to drill your own holes and tap them, I would recommend drilling, countersinking to a depth of 1-1/2 threads and tapping. Burrs from tapping will be below flush, and the "funnel" created by the chamfer will help guide the screws into the hole to start threading. Forty + years in the machine shop has taught me a few tricks.
His logic is quite sound but I see he explained it already.I don't follow your 'Logic'
Why does it matter how the holes were drilled/tapped or who did the work? What did I miss?
Mr. Pass' remark is the best answer, to247 and similar have an insulated hole so it really won't matter.
This related ONLY to the burrs/raised edge and to the poster's comment Mr. Pass quoted.
It DOES NOT apply to the situation of the bolt touching the pad and the interior of the drilled / tapped hole being conductive.
So... are you following?
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