Noobie trying to repair car stereo that went bang..

[ArgGrr]

Well not bang as such, but it did let off some smoke. Its a cheap car
stereo that plays mp3 cds too.

A MosFET seems to have taken a hit, and a diode. Its pretty hard to
accidently wire such a thing up wrong, i mean you have 2 wires that need
12v from diff places and an earth.

Anyways i dont have handy any replacement mosfets, and it seems even
getting some of the same type could be tricky.

Original.
1. RFD15P05 15A, 50V, 0.150 Ohm, P-Channel Power MOSFETs
(it has d15p05 written on it, this seems to match closely. Im guessing
its power switching for the 12v batt line..)

and the closest i have is a:
J177 P-channel JFET switch. in 3-pin TO-92 package. Operational
temperature range from -55°C to 135°C.

From the basic research i done myself im guessing its not gonna work to
well. Well it doesnt coz ive already tried, but i dont even know if i
got the pin outs hooked up right since i can find no real info on the
first mosfet.
And jfets have a higher open resistance, and the trigger voltage is all
diff? bah.

So i guess, any easy way to jerry rig the thing to work? ie remove the
mosfet and short it out, use some power npn or something?
Lets assume i cant get a replacement for the bit that went bang.


Cheers
Richard

 

[James Sweet]

Well not bang as such, but it did let off some smoke. Its a cheap car
stereo that plays mp3 cds too.

A MosFET seems to have taken a hit, and a diode. Its pretty hard to
accidently wire such a thing up wrong, i mean you have 2 wires that need
12v from diff places and an earth.

Anyways i dont have handy any replacement mosfets, and it seems even
getting some of the same type could be tricky.

Original.
1. RFD15P05 15A, 50V, 0.150 Ohm, P-Channel Power MOSFETs
(it has d15p05 written on it, this seems to match closely. Im guessing
its power switching for the 12v batt line..)

and the closest i have is a:
J177 P-channel JFET switch. in 3-pin TO-92 package. Operational
temperature range from -55°C to 135°C.

From the basic research i done myself im guessing its not gonna work to
well. Well it doesnt coz ive already tried, but i dont even know if i
got the pin outs hooked up right since i can find no real info on the
first mosfet.
And jfets have a higher open resistance, and the trigger voltage is all
diff? bah.

So i guess, any easy way to jerry rig the thing to work? ie remove the
mosfet and short it out, use some power npn or something?
Lets assume i cant get a replacement for the bit that went bang.


Cheers
Richard

Have you tried the cross reference on www.nteinc.com? It should be easy to
find some MOSFETs with similar specs that will work.

 

[ArgGrr]

Have you tried the cross reference on www.nteinc.com? It should be easy to
find some MOSFETs with similar specs that will work.

Didn't know that site or software existed. Thanks, should make life a
bit easier in general.

 

[Murbolt]

You can find the datasheet for original on www.digchip.com
Pin config is Gate, Drain, Source ( from left looking at front)

From datasheet:
15A, 50V, 0.150 Ohm, P-Channel Power
MOSFETs
These are P-Channel power MOSFETs manufactured using
the MegaFET process. This process which uses feature
sizes approaching those of LSI integrated circuits, gives
optimum utilization of silicon, resulting in outstanding
performance. They were designed for use in applications
such as switching regulators, switching converters, motor
drivers, and relay drivers. These transistors can be operated
directly from integrated circuits.
Formerly developmental type TA09833.
Features
.. 15A, 50V
.. rDS(ON) = 0.150W
.. Temperature Compensating PSPICE® Model
.. Peak Current vs Pulse Width Curve
.. UIS Rating Curve

Electrical Specifications TC = 25oC, Unless Otherwise Specified
PARAMETER SYMBOL TEST CONDITIONS MIN TYP MAX UNITS
Drain to Source Breakdown Voltage BVDSS ID = 250mA, VGS = 0V (Figure
11) -50 - - V
Gate Threshold Voltage VGS(TH) VGS = VDS, ID = 250mA -2.0 - -4.0 V
Zero Gate Voltage Drain Current IDSS VDS = Rated BVDSS - - -1 mA
VDS = 0.8 x Rated BVDSS, TC = 150oC - - 25 mA
Gate to Source Leakage Current IGSS VGS = ±20V - - ±100 nA
Drain to Source On Resistance rDS(ON) ID = 15A, VGS = -10V (Figure 9) - -
0.150 W
Turn-On Time tON VDD = -25V, ID » 7.5A, RG = 12.5W,
RL = 3.3W, VGS = -10V
(Figures 16, 17)
- - 60 ns
Turn-On Delay Time tD(ON) - 16 - ns
Rise Time tR - 30 - ns
Turn-Off Delay Time tD(OFF) - 50 - ns
Fall Time tF - 20 - ns
Turn-Off Time tOFF - - 100 ns
Total Gate Charge QG(TOT) VGS = 0V to -20V VDD = -40V, ID = 15A,
RL = 2.67W,
IG(REF) = -0.65mA
(Figures 18, 19)
- - 150 nC
Gate Charge at -10V QG(-10) VGS = 0V to -10V - - 75 nC
Threshold Gate Charge QG(TH) VGS = 0V to -2V - - 3.5 nC
Input Capacitance CISS VDS = -25V, VGS = 0V
f = 1MHz (Figure 12)
- 1150 - pF
Output Capacitance COSS - 300 - pF
Reverse Transfer Capacitance CRSS - 56 - pF
Thermal Resistance Junction to Case RqJC TO-220AB, TO-251AA, TO-252AA - -
1.875 oC/W
Thermal Resistance Junction to Ambient RqJA TO-251AA, TO-252AA - - 100 oC/W
TO-220AB - - 62.5 oC/W
Source to Drain Diode Specifications
PARAMETER SYMBOL TEST CONDITIONS MIN TYP MAX UNITS
Source to Drain Diode Voltage VSD ISD = -15A - - -1.5 V
Reverse Recovery Time tRR ISD = -15A, dISD/dt = -100A/ms - - 125 ns

Good Luck
Murbolt

 

[James Sweet]

Didn't know that site or software existed. Thanks, should make life a
bit easier in general.

It does, I use it all the time. You can download and install the software
but it's easier to just use the online one.

 

[ArgGrr]

As the subject suggests, how easy is it to replace a p-channel mosfet
with a n-channel moset?

P-channels are very hard to find, and i cant get a replacement for one
that burnt out on a car stereo. Lots of n-channels around though. is it
easy just to plonk them in, and use a bit of trickery to make them go?

Maybe in reverse or something.. i guess theres certain procedures laid
out for this now. I dont wanna rip the whole circuit to bits, but the
stero (cd/mp3 player) is worth repairing if its gonna work.

It was a D15P05 that burnt out.
15A, 50V, 0.150 Ohm, P-Channel Power MOSFET.

Closest i could find to buy locally was a 2sj16012, half the power, and
bloody expsensive.

 

[Wes.]

As the subject suggests, how easy is it to replace a p-channel mosfet
with a n-channel moset?

P-channels are very hard to find, and i cant get a replacement for one
that burnt out on a car stereo. Lots of n-channels around though. is it
easy just to plonk them in, and use a bit of trickery to make them go?

Maybe in reverse or something.. i guess theres certain procedures laid
out for this now. I dont wanna rip the whole circuit to bits, but the
stero (cd/mp3 player) is worth repairing if its gonna work.

It was a D15P05 that burnt out.
15A, 50V, 0.150 Ohm, P-Channel Power MOSFET.

Closest i could find to buy locally was a 2sj16012, half the power, and
bloody expsensive.

I doubt that this can be done, but I see that Digikey carrie this item as
"Non-Stock" (Pn-RFD15P05-ND). Contact them to see what the minumum order
quantiey would be to order this item in. I used Digikey to get a "Non-Stock"
stepper motor for Baytek's Wonder Wheel Game for just USD18 when Baytek wanted
USD80. Took 4 week but worth the wait for the price.

Wes.

 

[James Sweet]

As the subject suggests, how easy is it to replace a p-channel mosfet
with a n-channel moset?

P-channels are very hard to find, and i cant get a replacement for one
that burnt out on a car stereo. Lots of n-channels around though. is it
easy just to plonk them in, and use a bit of trickery to make them go?

Maybe in reverse or something.. i guess theres certain procedures laid
out for this now. I dont wanna rip the whole circuit to bits, but the
stero (cd/mp3 player) is worth repairing if its gonna work.

It was a D15P05 that burnt out.
15A, 50V, 0.150 Ohm, P-Channel Power MOSFET.

Closest i could find to buy locally was a 2sj16012, half the power, and
bloody expsensive.

You'd have to redesign the whole circuit, they use a more expensive P
channel part for a reason, an N channel is not suitable.