Awkward power tranny to heatsink spring clip

to

under

with

large

often

Thr best I can think of so far for clipping or unclipping. Grease in the slot and a small wedge to the thickness of the transistor laid to the side of the transistor and a thin covering of PTFA sheet over the wedge and transistor and lever or push or hammer+punch the spring clip across.

-- Diverse Devices, Southampton, England electronic hints and repair briefs , schematics/manuals list on

Looks like when the replacement transistor isn't yet soldered to the board you can lower it enough onto the board to lever open the spring and shift the transistor upwards under it. Messy procedure, though, with heat conducting paste applied.

I would seriously consider to mark the hole of the transistor onto the heat sink, take that off the board, drill a decent hole and to secure the transistor onto the heat sink with a screw and washer like it was always done in valuable devices :-).

Regards, H.

I bet that during manufacture, the devices are fitted to the heatsink first then the whole sink assembly fitted to the circuit board and soldered up by hand. I`ve seen it before where one bad transistor was impossible to remove without unsoldering them all and lifting them away with the metalwork.

Ron(UK)

Email reply from the amp maker's engineer "As to the spring clips, there is no real way of removing and refitting those, except by sliding them on to the heatsink slots. That can only be done when loose (no devices in place ). Hence, they have to be mounted on to the heatsinks before sliding them over the devices."

My bit of (clothes line peg) wedge and ptfe sheet method did work but if the applied force along the slot, is not axial to it then the high-C steel clips easily dig into the aluminium and jam fast. I found a large pair of engineers cramps would gradually inch it across, taking up the slack every few mm , and starting again. Just another thought, with a pair of large sewing thimbles on opposing finger/thumb you may be able to use enough finger pressure to slide the clip up the wedge. But otherwise matter of desoldering the power devices and removing the heatsink with trannies and then the trannies can be easily slid out from under the springs.

-- Diverse Devices, Southampton, England electronic hints and repair briefs , schematics/manuals list on

Absolutely. Having fiddled with these things often enough it is hard to imagine how volume output can be achieved otherwise.

Regards, H.