Unfortunately no. I tried to change the HCT139 and pulled two traces off the board. I set it aside for now for when I have more time to attempt a repair.
Posts by Kazz
Caution: Non registered users only see threads and messages in the currently selected language, which is determined by their browser. Please create an account and log in to see all content by default. This is a limitation of the forum software.
Also users that are not logged in can not create new threads. This is a, unfortunately needed, counter measure against spam. Please create an account and log in to start new threads.
Don't Panic. Please wash hands.
-
-
Thank you for the technical support. The part will be here tomorrow and I’ll update you with the results.
-
What temp range ( minimum to maximum) would you recommend?
-
I just ordered a few of the 74HCT139D Should be here in a few days. I will keep you updated on the results.
Anything special I should be concerned about while changing that chip?
-
Also this one
-
See if this helps
-
I did use a diagnostic cartridge on the MK2 with different CIA chips that came from a working C64. It says both CIA u1 & u2 are bad even though they are not.
-
The MK2 was off when I inserted it. I was trying to make a connection to a PC using a null modem cable. Tried various baud speeds and couldn’t get the connection. Shut off the MK2 and pulled the link232.
Have not done any repairs on the link232 yet. Haven’t had the chance.
Not sure about the signals but I have some schematics for the link if that’s helpful?
-
Amendment to my first post “Recently” purchased = maybe 6 months
Worked great for all that time and quickly became my daily use machine.
-
I’m not questioning the QC of your board and staff. I own a ton of you products.
I suspect something shorted when I was setting up the untested link232.
I have been working with a friend on diagnosing of the problem just like it was a regular c64. I have swapped every chip and tested them in another board.
I removed the SIDs and booted it, replaced the CIAs, CPU and Vic. We’ve exhausted the limits of what we can do without getting into the board.
Just looking for some options or suggestions?
-
Update. I socketed one of my breadbin C64’s and tested the CIAs in that and they work. So the issue is not the CIAs in the MK2.
What next?
-
As far as the CIA chip orientation.... I was very careful to make sure they were correct. Every time.
-
I don’t have a freeze cartridge but I do have The final cartridge III. When I plug it in and turn it on the cartridge menu comes up but the arrow can no longer be controlled by the keyboard.
-
Is there something on the board that could short and show both CIAs as bad?
-
My recently purchased MK2 screen went blank while I was setting up a Link232 cartridge linked to my PC. I shut the MK2 power off and removed the link232.
I booted the MK2 back up and it booted fine just no cursor. When this happens as you know it more than likely a bad CIA chip. I swapped them out and no change. I tried another set and still no cursor.
I plugged in a diagnostic cartridge and it listed both CIAs as bad. I did this with 6 different chips and the result was the Same. I hooked the MK2 up to term and updated the firmware in case that is an issue. No change. I’m hoping someone could help with this.
Keith