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Boss BR600, digital recorder, 2006

N

N_Cook

Jan 1, 1970
0
Boss BR600, digital recorder, 2006
Q47 an 8pin SMD presumably a powerFET switch, with an erupted hole in
it. Marking
BB
??F1
probably ?? as 1 or 2 missing characters
3 connected pins of the IC go to batt -ve, single pin via R2 a fusible
resistor of .3R to batt +ve (9V), and 4 pin combination on to the rest
of the circuit via the on/off switch.
Quite a bit of space to fit something bigger than the original, but what
sort of rating or identity and then data for a BB??F1 top code SMD ? So
far not found an 8pin BB powerfet identity

further reading
http://www.thegearpage.net/board/archive/index.php/t-508133.html
but no identity of the powerfet,
www images swamped with external views of course and 1 out of focus pic
of the diode fudge in the above thread
 
N

N_Cook

Jan 1, 1970
0
The Service Manual identifies it as VEC2302



Gareth.

Ta for that
Dual p-ch 3A,30V, buried in the datasheet Marking: BB
With the ex-SOIC off the board then traces are consistent with the
pinout of that IC with both devices paralleled
 
N

N_Cook

Jan 1, 1970
0
Both devices are in series:

S1 -- D1/D2 -- D1/D2 -- S1

1 7 8 5 6 3

This is in parallel with the not fitted D2, so you can just fit a diode in
position D2. Maybe a Shottky.

D2 Anode ----------- D2 Cathode



Gareth.



Gareth.

I was going to put an IRF9532 in there as plenty of space for a TO220
but I've no idea what the seriesing is all about so a couple of
paralleled shottky SM diodes went in at D2 pads, reassembling/testing
next week.
 
N

N_Cook

Jan 1, 1970
0
Owner lost the original plug in ps, and tried using another 9V one of
the wrong polarity. I changed the connector and polarity and the unit
worked for about 10 hours and then bounced back. So something to do with
reverse polarity stressing or knocking out one powerFET initially but
continued for those 10 hours with the other one or something like that
 
N

N_Cook

Jan 1, 1970
0
Owner lost the original plug in ps, and tried using another 9V one of
the wrong polarity. I changed the connector and polarity and the unit
worked for about 10 hours and then bounced back. So something to do with
reverse polarity stressing or knocking out one powerFET initially but
continued for those 10 hours with the other one or something like that


Talking to an engineer familiar with solar PV controls. He was reminded
of the anti-shadowing bypass "diodes" in solar panels. Otherwise a
shadow over as little as one cell will kill the output of the whole
array, so as little as a good dollop of seagull shit is all that is
required. Say 50 cell panels and each sector of 5 can be bypassed by one
of these 2pin powerFET devices built into each panel , output falls in a
sector below a trigger level and "diode" kicks in bypassing the 3amps or
so of the rest of the array but only dropping .05 volt, so overall array
efficiency drop of 1% instead of 90% or whatever with the shadow of a
chimney or telephone pole or whatever.
 
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