Batboard

i have a M1225 that currently doesnot function. it had reverse polarity applied to it.

an unlabeled large diode near the positive lead wire unsoldered itself from its leads. when i replace it, the unit still doesnt function. i checked the large diode near the negative lead and it shows ok. anybody have a schematic they can look at to tell me whats next in line to check, or if they have expierenced this and know the solution i would really appreciate the help.
thanks,
wazz

Wazz,

If the reverse polarity diode became unsoldered, it must have taken a prety hard 'hit' due to too large fuse, or no fuse in the power lead. The diode is rated at about 35 Amps surge, and is suposed the blow the fuse in the power cable.

If the diode failed open, by becoming unsoldered due to excessive disapation (short circuit current), the rest of the radio may be 'fried' too. Check the 9.6 and 5 volt regulators next.

I would also check the green Pico fuse in the rear left corner. Reverse voltage also has a bad habit of taking out the final PA and sometimes the driver as these are connected to unswitched B+.

Regards,

Allen

THE GREEN FUSE WAS BLOWN!! replaced it and all is good. next in process, put a fuse in the supply!!!

wazzzzzzzzup wrote:THE GREEN FUSE WAS BLOWN!! replaced it and all is good. next in process, put a fuse in the supply!!!

GREAT, gald the hear, BUT be sure the replace the "big'' diode!