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CBM720 with defective crtc

braids

Member
Joined
Nov 12, 2010
Messages
18
Dear users,

I've got a CBM720 fitted with an original MOS 6545A-1, unfortunately unsocketed. When i check the video outputs,
all three signals remains high. I've also checked data input with a logic analyzer but no failure found. The question:
does i reduce the worth of the machine when i 1. add a socket 2. replace by a rockwell or motorola (68B45) when i
don't find an original part between useful time.

Yours Sincerly,

braids
 

sjgray

Experienced Member
Joined
Feb 3, 2009
Messages
467
Location
Markham, Ontario, Canada
I don't think you will reduce the value. 720's are not very common, so having a working one would be preferable to an "original condition" non-working unit. I am surprised that the 6545 is not socketed... Just checking... Is your 720's serial# greater than 2599?

Steve
 

carlsson

Veteran Member
Joined
Jul 30, 2003
Messages
6,275
Location
Västerås, Sweden
I agree with the others, working machine should be worth more than untouched machine, at least as long as the exterior isn't damaged. Besides, my impression is that the availibility of sockets in Commodore computers depended on which factory it was, which worker did the assembly and the phase of the moon so there might as well exist CBM 720's with similar serial# as yours where the 6545 is socketed. I should check mine in the basement some day.
 

Gabriele72

Experienced Member
Joined
Aug 2, 2012
Messages
111
Location
Italy
Me too, I do agree with others, adding a socket to an inner motherboard is not altering its original status, besides repairing a faulty machine can only add value it. I wouldn't mind about the chip either, the 6845 is a perfect replacement. Otherwise, you should also coherently look for chips with suitable datecodes, shouldn't you? :) But that would probably make sense only for an hand assembled and iconic machine like the Apple I, not for a factory product.
However I have a 710 and a 720, now I'm not at home but I'm curious to take a look and see if the crtc is socketed.
 

braids

Member
Joined
Nov 12, 2010
Messages
18
Today evening i had temporarely (without solder) fixed the computer with a 68B45 from heap. The computer is now back to life.
Also found a supplier for mos 6545A-1 in germany. When i got the spare parts then i will do the fix definitively.


Thanks, Braids.
 

braids

Member
Joined
Nov 12, 2010
Messages
18
Hi All

After getting spare parts i done the machine finally fixed.

Thank You.

Braids
 
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