How to remove transistor heatsink clamp - Page 1
Forum section: electronics / repair

author: technoviking
author_rank: Newbie
timestamp: September 26, 2021, 09:33:05 am
content: I've got a motor controller that let out the smoke that I'd like to attempt to repair. The problem is that it is housed in an aluminium extrusion with the mosfets clipped to the housing and I have no real idea how to remove or re-install the clips.I´ve seen guides online on how to do this for clips that have a little slot in them, but these don't have that.If it's of any help the clips model number is MAX02H

author: technoviking
author_rank: Newbie
timestamp: September 26, 2021, 09:39:53 am
content: For the curios this is where the smoke escaped. I'm taking any bets on what took out what, Capacitor vs NTC

author: jpanhalt
author_rank: Super Contributor
timestamp: September 26, 2021, 09:58:48 am
content: The retainers look like they are simply held by spring compression between two narrow fins. A little wiggling will remove them.The bigger question is why do you want to remove them? That is not where the problem was. That disk shaped thing is probably some sort of protective element like a MOV (https://en.wikipedia.org/wiki/Varistor).

author: strawberry
author_rank: Super Contributor
timestamp: September 26, 2021, 10:51:14 am
content: NTC inrush current limiting resistor.

author: xrunner
author_rank: Super Contributor
timestamp: September 26, 2021, 11:12:26 am
content: Quote from: jpanhalt on September 26, 2021, 09:58:48 amHow is he going to repair the board (replace components) without removing it?

author: DavidAlfa
author_rank: Super Contributor
timestamp: September 27, 2021, 12:40:55 am
content: Quote from: strawberry on September 26, 2021, 10:51:14 amIt also could be a VDR, to mitigate voltage spikes. They have very similar packaging.

author: fzabkar
author_rank: Super Contributor
timestamp: September 27, 2021, 03:59:57 am
content: Quote from: DavidAlfa on September 27, 2021, 12:40:55 amThere is "NTC1" marked on the PCB nearby.

author: BrokenYugo
author_rank: Super Contributor
timestamp: September 27, 2021, 04:42:20 am
content: Looks like you just slip a screwdriver between the heatsink and clip and pry it out of the groove.

author: Ian.M
author_rank: Super Contributor
timestamp: September 27, 2021, 05:57:14 am
content: Prying them out would probably distort the spring clips or damage the groove in the heatsink they are press-fitted into. Instead lift them all slightly, by sliding in the shaft of a screwdriver (or other smooth cylinder with a chamfered end) of a diameter that just lifts the clips off the transistor bodies, then you should be able to slide the board out cleanly, though if its been undisturbed for years, you may have to pry gently to unstick each transistor from the silpad.

author: Alti
author_rank: Frequent Contributor
timestamp: September 27, 2021, 08:01:25 am
content: Linkto MAX CLIPFrom their "Clip and Rail Thermal Solutions":QuoteHowever, I have not been able to find any explanation about how to actually unclip this thing without damage.

author: perieanuo
author_rank: Frequent Contributor
timestamp: September 27, 2021, 09:22:46 am
content: slide them one by one, but i think they will block in that aluminiumanother way is to pull him out with something like a bent plier (dunno how the call this in english sorry)or, if the shorted transistor is in the middle, cut his legs, remove it, then the clip will come out easily because the 'spring' will be not tensioned. that's my option no 1 cause i'm lazy

author: aqibi2000
author_rank: Regular Contributor
timestamp: October 02, 2021, 12:03:12 pm
content: Pull out with pliers mate

author: Audiorepair
author_rank: Frequent Contributor
timestamp: October 02, 2021, 06:57:41 pm
content: Angle grinder.

author: WattsThat
author_rank: Frequent Contributor
timestamp: October 03, 2021, 02:38:42 am
content: Commonly used on small inverters (<1kw).You’ve got to pry them out from the back of the top slot. A sacrificial ~2.5mm flat bladed screwdriver works well, slid in behind the smaller curled top. The clips can be reused, the silpads usually don’t fair so well.

author: CJay
author_rank: Super Contributor
timestamp: October 03, 2021, 09:48:50 am
content: Plasma cutter.Seriously though, they're pushed in, they pull out.

author: Dacke
author_rank: Regular Contributor
timestamp: October 03, 2021, 05:34:45 pm
content: Arc furnace.Or pliers