Title: My New EII, some problems, any suggestions? Post by: tomc on May 30, 2012, 05:46:43 AM Just got an EII yesterday.
1st few times switched on, it got to boot screen, and no further. So I opened up, reseated a few memory ICs around what I think is first segment (IC13 area?) - used some deoxit and replaced. Then this time, it booted up and all seemed good. A Bank loaded. I then tried to load a bank from another floppy, started loading, then after a bit froze and blanks screen. Since then I have removed and reseated just about every IC on the digital board. Generally all I get is black blocks on the top row of the LCD, nothing on second. And usually ALL of the LEDs lit. about 1/10 times I might get the boot screen, but no further (doesnt try to read discs). So in theory most of the machine is OK since I got as far as loading 1 bank. Wondering if this is a bad connection somewhere. Maybe RAM/Scanner problem? Can any suggest anything I can try? Which Ram ICs should I check first, Any tips appreciated. I am very good with electronics, however, not too familiar with EIIs (but learning fast!) Title: Re: My New EII, some problems, any suggestions? Post by: tomc on May 30, 2012, 05:48:17 AM BTW, oddly, my boot up screen is unique(?)
**Emu 3-1 SC *** Mulhouse 1-02-90 custom? maybe just the message has been changed? (maybe Mulhouse is one of the previous owners?) Title: Re: My New EII, some problems, any suggestions? Post by: sfbaytech on May 30, 2012, 09:22:08 AM These are classic symptoms of corrupt memory (that is why you have garbage displayed). If you are lucky it is just a memory chip, and your first task is to run the memory test (if you don't have a test floppy then you can download and burn a diagnostics eprom from the Yahoo group). If the test fails and it is not a chip (takes a bit of decoding and reference to the schematic to figure out which RAM chip) but is location sensitive it is often a corroded pin on the socket. The other thing that could be happening if memory tests good is that bad data is coming from the floppy, but if you have 2 drives you can isolate that (plus the diag eprom has a disk exerciser).
This is the easier stuff on an EII, and diagnosing the harder stuff is patience, a scope, and the schematic (and I have spent too many hours at that on EII's). You should also check your power rails (but don't start twiddling pots), with a common issue being dry joints/high resistance connections at the psu output. Chris www.thisoldsynth.com Title: Re: My New EII, some problems, any suggestions? Post by: tomc on May 31, 2012, 06:32:01 AM if any one out there is listening (this is a quite forum!)
I am both a genius and an idiot, I found, that after cleaning IC sockets, I put a Zilog back in wrong >:( Fixed that, and now reliably boots each time. But no sound :( So I will run a memory test next Title: Re: My New EII, some problems, any suggestions? Post by: dr.c on July 12, 2012, 05:15:31 AM Mulhouse is a damn city in Alsace ! And you live at 117 km (roughly 70 miles) of it, at Strasbourg !
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