Thanks for the thoughts, Shawn.
We are still investigating the source of the "growth".
No, the transistor no longer works.
Cheers, Dave
Upton, Shawn wrote, On 25/06/2008 1:14 a.m.:
> I wonder though if temp spiked suddenly, enough to cook the part but not
> enough to heat up the PCB? Well, above what the PCB had already been
> cooked--it does have some discoloration. I'm wondering about sudden
> spike, then the transistor goes open circuit. Fast enough to blow the
> guts out, but not long enough to discolor the pcb above and beyond what
> it has already seen.
>
> Thermal compound and/or flux residue interacting with whatever leaked
> out of the power transistor when it went? Almost looks like is left
> over in the oven when a pie (high in sugar) has a spillover.
>
> Lastly, just to verify: the transistor is bad, right? Or is it still
> working?
>
> Shawn Upton, KB1CKT
> Test Engineer
> Allegro MicroSystems, Inc
> [log in to unmask]
> 603.626.2429/fax: 603.641.5336
>
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of Guy Ramsey
> Sent: Tuesday, June 24, 2008 5:04 AM
> To: [log in to unmask]
> Subject: Re: [TN] Power amplifier growth
>
> Looks like less of a growth and more of transmogrification.
> Looks like Q100 got pretty hot.
>
>
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of Dave Elder
> Sent: Tuesday, June 24, 2008 1:01 AM
> To: [log in to unmask]
> Subject: [TN] Power amplifier growth
>
> Has anyone seen anything like this?
> The growth is on a 100W power amplifier that has been sitting, powered
> up, under load, on a desk, for six months.
>
> Dave
>
> http://sites.google.com/site/taitpcb/
>
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