bad full-wave rectifier?

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unclejed613 said:
rubbing some white heat sink grease into the lettering and wiping off the excess makes them easier to read.
Click to expand...

I can verify this is a good trick, and it works on black laser-etched chips, too. Going over it with a white pencil also works well, I keep one in my toolbox for this, you can get the pencils at art supply and fabric stores.
 
Thanks duffy i tried with a white cream i could only get the description of q10, boston has purposely scraped the part number on the other two transistor
 
Bastards! Scraping the part number off only causes problems for people trying to do repairs. It certainly doesn't stop reverse-engineering.
 
that's really funny too since the usual warranty repair for this type of amp is to replace the whole amp,

unless the part numbers were on there in ink, and you just can't read them...
 
As i type this message i am listening to the boston hps10ho fixed 10 mins back, it sounds awesome with tight bunch. Thanks to everyone who supported and helped me in fixing it. I am delighted to have it fixed. Good night
 
thanks to forum like this we are able to fix, cause in Kuwait there are no techs nor are the service centres helpful in getting it repaired
 
I have the same problem, did you figure out the transistors replacement numbers? Yes, it looks like they intentionally used paint or etching acid to remove them.
 
Where did you find the part numbers off the three transistors?

 
I think I found it on a JBL schematic. Did these FETs fix your problem or was it cap or bridge rectifier? I have the blown fuse issue and I measured these with the DMM and they look to be shorted. That's the three power transistors on the heat sink.

FET IRF9640 IR P-CH TO220(RoHS) 2 Q10,Q10B,
F640N-E Transistor IRF640N INTERNATIONAL(RoHS) 1 Q11,
 
Hello,

The requested details is as follows:
Q10 which is IRF 9640 and did further search and found the same mosfet irf 9640 at location Q 10 in the infinity subwoofer schematic which is attached above, with the help of this schematic what i understand the part number of Q10 and Q 10b will be similar which is IRF 9640 and q11 is IRF640.

After you have changed the part, connect a 100 watt bulb at the fuse point in series, so if there is any other problem it will prevent the board from burning it will glow in the begining and then get dim if the circuit is correct if not the bulb will be bright throughout .

Hope it helps you......

All the best
 
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