commodore 128 DCR Do not start

[turican5]

hello to all, I recover a c128dcr, it does not start the leds of the floppy lit permanently and the led power works
+5v ok
+12v+ok

 

[roy_bates]

try removing the drive somehow,apart from that youd have to start looking at the schematics

it wont be easy to help going by that sort of information

or see if it will go into 64 mode

 

[turican5]

try removing the drive somehow,apart from that youd have to start looking at the schematics

it wont be easy to help going by that sort of information

or see if it will go into 64 mode

thank you I'm waiting for a monitor to try on a screen

 

[roy_bates]

you missed a voltage by the way,there is an ac side like the c64

how do you know it dont work,as your giving the impression you havnt tried it,its got the same video port as the c64


EDIT: actually here is some obvious simple stuff you can try,see if the roms havnt got chip creep,reseat them all.then try the reset line everywhere,this machine requires the z80 start first,and i think it has a strange pullup arrangement for the clock signal derived from the ac side converted to 12 volts so better to start with simple voltage checks

i think the disk drive circuitry is on the mainboard,so it might be a bit tricky to fault find

you could also have bad ram..so lots to look at

mostly when these die its like the c64 you could have a black screen which could be anything

 

[turican5]

you missed a voltage by the way,there is an ac side like the c64

how do you know it dont work,as your giving the impression you havnt tried it,its got the same video port as the c64


EDIT: actually here is some obvious simple stuff you can try,see if the roms havnt got chip creep,reseat them all.then try the reset line everywhere,this machine requires the z80 start first,and i think it has a strange pullup arrangement for the clock signal derived from the ac side converted to 12 volts so better to start with simple voltage checks

i think the disk drive circuitry is on the mainboard,so it might be a bit tricky to fault find

you could also have bad ram..so lots to look at

mostly when these die its like the c64 you could have a black screen which could be anything

thank you for your help, I do not have a monitor to try at the moment, the AC voltage is 11v, on my tv lcd I can not have an image via the RF

 

[turican5]

I find a screen, alas gray screen nothing even in rf, I'm looking for a person able to repair it