My 988 chassis is dead again...

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Orkie
Posts: 29
Joined: August 20th, 2008, 8:34 am
Location: Surrey, UK

My 988 chassis is dead again...

Post by Orkie »

Well the hot weather managed to make some parts move around and unknown to me at the time, the horizontal transistor (Q401) somehow managed to detach itself from the heatsink and so died... I bought some BU2520DFs and BU2520DXs to replace the 2SC4742 as the datasheet suggested, but simply fitting them and popping in a new 2A fuse doesn't seem to have helped - the fuse still blows whenever I apply power! I have disconnected the degauss cable; tried removing the heat thingy that goes with it and I have tested the rectifier and that isn't shorted to ground.

However, I do get a very low resistance when testing between either of the two outer pins on Q401 and ground, presumably through L402 or C496. I can't remember if this is normal or not.

I still have the schematic online if that gives any clue: http://x11.gp2x.de/tempfiles/arcade/CH-988.pdf"

Thanks
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grantspain
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Posts: 4823
Joined: August 17th, 2008, 4:23 pm
Location: down south

Re: My 988 chassis is dead again...

Post by grantspain »

those bu2520 are known to be problems,i never use them
i would install the original type
Orkie
Posts: 29
Joined: August 20th, 2008, 8:34 am
Location: Surrey, UK

Re: My 988 chassis is dead again...

Post by Orkie »

I would use a 2SC4742, but I am having difficulty finding one. Grandata has stopped stocking them, the ones I got off eBay seemed to be cheap knock offs (it looked like the labels had been printed on after manufacturing) and didn't work anyway (they got completely fried when I turned on the machine).
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grantspain
Tech Head
Posts: 4823
Joined: August 17th, 2008, 4:23 pm
Location: down south

Re: My 988 chassis is dead again...

Post by grantspain »

i am not sure what to suggest,i never use the phillips transistors as they shat out on power up with every chassis i used them on
http://www.dalbani.co.uk/search.php"
Orkie
Posts: 29
Joined: August 20th, 2008, 8:34 am
Location: Surrey, UK

Re: My 988 chassis is dead again...

Post by Orkie »

Well I e-mailed Grandata to see if they had just forgotten to list them on their new site and they had, so I will order them from there and see if it works again with the real part (the only down side I am going to have to buy 7 of them to meet the new minimum order) :D. I did look on dalbani.co.uk before, but they don't accept my card :(.

Thanks
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