Post Reply 
Found these inside a non-working 71B
03-15-2018, 02:22 AM (This post was last modified: 03-15-2018 03:22 AM by MikeSD.)
Post: #97
RE: Found these inside a non-working 71B
Thanks. i'll look at schematics.

Turns out it's a little more complicated than I thought. I still think the problem is a connection. But it fluctuates between 4K and 2k, missing. And the exact numbers seem odd. i removed the 64k since those are reportin gòod.

The only RAM chip I soldered to is the top chip on other side of board. The only thing that makes sense is if one of the nibble lines is open, to cause it to toggle betseen the two values.

oh well, on to tomorrow.

thanks for schematic. much better than my copy

Update: When I have a problem, I just can't let it go. The only thing that made sense was my unsoldering the 64k RAM from the 4K RAM chip. So, I reflowed the solder on that chip and now its working again. Only FORTH to go, then final button down and test.

[Image: 64k_loc.jpg]
Find all posts by this user
Quote this message in a reply
Post Reply 


Messages In This Thread
RE: Found these inside a non-working 71B - MikeSD - 03-15-2018 02:22 AM
What's U10? - Dave Frederickson - 03-15-2018, 03:43 PM



User(s) browsing this thread: 2 Guest(s)