hello ,
i need some help to try fiwing a mrvt505 amp;
sudenly stop working
open it : Q503 and Q504 are blown, all pins shorts.
so remove them, and replace
Q503 was readable : irfz44 but not Q504
Q505 and Q506 just near them are all irfz44
so i replace both with irfz44n
no shorts then
so i plug it in the car and mosfet blown again !
what can i check please ? (no other part seems burnt)
thank you
i need some help to try fiwing a mrvt505 amp;
sudenly stop working
open it : Q503 and Q504 are blown, all pins shorts.
so remove them, and replace
Q503 was readable : irfz44 but not Q504
Q505 and Q506 just near them are all irfz44
so i replace both with irfz44n
no shorts then
so i plug it in the car and mosfet blown again !
what can i check please ? (no other part seems burnt)
thank you
Post a good quality photo of the component side of the entire main board and the component side of any driver boards if no one can help.
If you find a copy of the service manual, post it. I couldn't find it on any of the free sites.
If you find a copy of the service manual, post it. I couldn't find it on any of the free sites.
Are you sure that all 3 of the D-shaped (TO-92) transistors are C3198s?
Did you check the C3198 transistors for leakage and open junctions (would require removal)?
Did you check the C3198 transistors for leakage and open junctions (would require removal)?
after pull them, in diode mode got exactly same thing on both
727 red probe on pin 1 and black on pin 2
732 red probe on pin 1 and black on pin 3
all other test give OL
727 red probe on pin 1 and black on pin 2
732 red probe on pin 1 and black on pin 3
all other test give OL
Remove all 4 Z44s and measure the DC voltage across pad 1 and pad 3 (black).
Do all read the same?
Do you have any small capacitors (0.01uF - 0.1uF)?
Do all read the same?
Do you have any small capacitors (0.01uF - 0.1uF)?
q505 is short between 2 and 3 , both sense (RP2 BP3 and RP3 BP2)
the other z44 give ol or positive value
the other two exploded are exploded and short
can only this Q505 can kill the other line ?
the other z44 give ol or positive value
the other two exploded are exploded and short
can only this Q505 can kill the other line ?
sorry mistake.
in fact the two residual z44 have not the same value
short is just active mosfet, after discharge got same value as new one.
but the other with positive value has not the same as new, here are the values :
red probe first, black second
1-2 : 1400 instead OL on new
1-3 1100 instead OL
2-3 : OL even after activation (new gives OL and 0 after activation)
3-1 : 1060 instead OL on new
3-2 : 515 as new one
in fact the two residual z44 have not the same value
short is just active mosfet, after discharge got same value as new one.
but the other with positive value has not the same as new, here are the values :
red probe first, black second
1-2 : 1400 instead OL on new
1-3 1100 instead OL
2-3 : OL even after activation (new gives OL and 0 after activation)
3-1 : 1060 instead OL on new
3-2 : 515 as new one
Solder that capacitor between pads 1 and 3 for each FET (one at a time). With the cap in place, measure the DC voltage across the legs of the capacitor. The capacitor needs to be a film capacitor.
Do all read the same?
Do all read the same?
damn, i had resoldered them.
i tried to turn it on on power supply (not good i know but so excited) : now with 8.5V 2amp limit; i ve got sound on both channel with a simple mp3 player.
can i test voltage like you tell me with fets or it is to late ?
thank you sir
i tried to turn it on on power supply (not good i know but so excited) : now with 8.5V 2amp limit; i ve got sound on both channel with a simple mp3 player.
can i test voltage like you tell me with fets or it is to late ?
thank you sir
The test is to prevent damaging the FETs so you test without them.
It takes just seconds to remove the FETs. Apply additional solder so that you can lay your soldering iron across all 3 terminals. When all are hot enough, pull the transistor out of the board and desolder the pads.
Have you confirmed that you don't have any shorted output transistors?
It takes just seconds to remove the FETs. Apply additional solder so that you can lay your soldering iron across all 3 terminals. When all are hot enough, pull the transistor out of the board and desolder the pads.
Have you confirmed that you don't have any shorted output transistors?