16 Apr
2012
16 Apr
'12
6:07 a.m.
David Riley wrote:
On Apr 16, 2012, at 7:57 AM, Holm Tiffe wrote:
It's near the same in english, "~ I've decided to do a brutal action.."
...since I don't trusted the isolation capabilities of the burned pcb
anymore. This all looked pretty much like pure carbon (wich it not
was..)
If the unit is switched of with the on/off Button on the front, the parts
in the PSU heating up to around 45?C (~115?F). The Fan isn't working in
this case. I don't think that this alone is enough to toast the PCB like
it was.
I don't know the function of the Part in question until now, I think
this makes some standby Power for the PSU itself. I've tried to trace what's
going on there, but it is getting to complicated.. 2 boards, 3
Transformers, one is connected over a diode to the wirewound resistor and
than to the drain of the FET ...???
...and not even the Pinout of the connectors on the PSU.
I think the FET was blown sometime in the past and the Resistor was
overloaded then. That dosn't prevented the PSU from working..it was only
the burning smell that alarmed me..
Regards,
Holm
--
Technik Service u. Handel Tiffe, www.tsht.de, Holm Tiffe,
Freiberger Stra?e 42, 09600 Obersch?na, USt-Id: DE253710583
www.tsht.de, info at tsht.de, Fax +49 3731 74200, Mobil: 0172 8790 741
For sure the towel doesn't help in this case
but....
http://www.robotrontechnik.de/html/forum/thwb/showtopic.php?thread[threadid…
Ouch. Yeah, that looks like the wirewound resistor (at least) got
WAY too hot. You can see the FR-4 fibers poking through, which
means the board temperature was probably way above design (assuming
a reasonable thermal design). Still, I'd be surprised if it were
fatal damage, especially since it's probably a 2-layer board with
no plated through holes. I imagine it's not too structurally sound
anymore, though (I guess that's why you put in the perf? My German
isn't so good, though I think I can guess what "brutalen Aktion"
means).
- Dave