Closed Someone To Help Diagnose/Repair 2 Broken Commodore 128D Systems

[djgarf]

hi all
i have 2 broken commodore 128d systems and was wondering if their is anyone in the uk (ideally within 100 miles of bristol) who could help me fix them up and get them working again
both power up fine but neither of them display any sort of picture
i have opened both up and their is nuffin obvious i can see and i have tested both of the power supplies and they are pumping out the correct voltages but as i dont own a oscilloscope i cant really go any further than i have in diagnosing and repairing them
i would be more than happy to pay someone to fix them, its just finding someone who can lol

cheers

 

[PymerOne]

Dear DJGarf,

sorry to say, i live far away and have only little knowledge of the C128D.
For progress's sake, could you supply pictures of the mainboards (preferably with cables attached).
Troubleshooting surfacemounted issues is sometimes just a mater of looking real close...
(please read "soldered connection" where i wrote "weld"...i am lazy).
-leaking capacitors make the weld that connects them to the mainbord go dull (or more dull than the other welds on the same board)
-cold/broken weld is just a thin dark line on the weld, eazilly cured by re-heating it (may need a tiny bit of flux/S39)
Also, if there is socketed chips on the mainboards, did you try and pry them a tiny bit up and push them firm into the socket?
Did you blindly type "go 64" just for fun? probbably won't do anything, but hey, i did mention -for fun-

Grtz, PymerOne.

 

[gazcbm]

My guess would be the PLA or RAM chips

take a look at Ray Carlsen's site
http://personalpages.tds.net/~rcarlsen/cbm/C128-IC.txt

 

[djgarf]

have checked the info at rays site but without a oscilloscope im pretty much at a dead end now
the voltages are fine when read from certain points on the board so it's definatly not a power issue
neither machine will do anything (even with a c64 cart attached)
i mite just have to bite the bullet and pick up a cheap oscilloscope,im sure i will find it useful for future little fixing jobs