Greetings.
I started working on a badly neglected Model 4 about a month ago. I began by replacing the power supply with an Astec model AC9335-01.
Next I replaced the display with a 12VCMP4. Don't ask why i needed to. The price was right, but the web page did not indicate the tube would be refurbished. With the brightness turned all the way up, the text is just barely visible. Unless something else is going on, I would not recommend this purchase at any price.
Now the machine would boot LDOS, cool, maybe it's not in that bad shape. Unfortunately most of the keys didn't work. Neither did drive 1. I removed all the keys, cleaned them, and replaced eight bad ones (thanks Ian). That fixed the keyboard... all keys showing up nicely in Basic.
I installed a 64K upgrade along with the associated GAL needed for the non-gate array Model 4 (thanks again Ian). For some reason the machine now no longer boots. I get "Cassette" on the display but no red light on the drive upon initialization. If I close the drive immediately after turning it on I do get the solenoid sound however. I took out the 64K ram upgrade, GAL, and replaced the shunt. Same same, no boot.
It looks like the main motherboard needs to be removed in order to access the floppy disk controller. Looking at it I don't see any way to lay it all out with everything connected in order to test.
Not sure where to begin here... any ideas?
Thank
I started working on a badly neglected Model 4 about a month ago. I began by replacing the power supply with an Astec model AC9335-01.
Next I replaced the display with a 12VCMP4. Don't ask why i needed to. The price was right, but the web page did not indicate the tube would be refurbished. With the brightness turned all the way up, the text is just barely visible. Unless something else is going on, I would not recommend this purchase at any price.
Now the machine would boot LDOS, cool, maybe it's not in that bad shape. Unfortunately most of the keys didn't work. Neither did drive 1. I removed all the keys, cleaned them, and replaced eight bad ones (thanks Ian). That fixed the keyboard... all keys showing up nicely in Basic.
I installed a 64K upgrade along with the associated GAL needed for the non-gate array Model 4 (thanks again Ian). For some reason the machine now no longer boots. I get "Cassette" on the display but no red light on the drive upon initialization. If I close the drive immediately after turning it on I do get the solenoid sound however. I took out the 64K ram upgrade, GAL, and replaced the shunt. Same same, no boot.
It looks like the main motherboard needs to be removed in order to access the floppy disk controller. Looking at it I don't see any way to lay it all out with everything connected in order to test.
Not sure where to begin here... any ideas?
Thank