EmulatorII-list

these early computer based units are very sensitive to the exact voltages on the PSU.  there's often a sensing procedure at startup and if the voltage is out even my millivolts the computer may not come on line properly.  if it's close enough to boot the extra draw caused by engaging the disk drive could pull the PSU out enough to crash the system.  the caps decay functionally over time so they may work for several minutes and then not once they warm up...
 
the whole piece will work better with a happy PSU.

z



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________________________________
 From: hazchem88 <analoguesolutions@...>
To: emulatorII-list@yahoogroups.com 
Sent: Wednesday, May 30, 2012 11:22 AM
Subject: [emulatorII-list] Re: just got another EII - this one only boots sometimes.Can any one suggest things
 

  

The PSU 'appears' to work, as in it did boot up once, and nearly a couple of times. The 5V rail is all OK.

So is replacing electrolytic caps just a tip for dead PSUs, or do you think it's worth a shot in my case?

--- In emulatorII-list@yahoogroups.com, Robert Van Kuran <guitar5l50@...> wrote:
>
> Try replacing all of the electrolytics in the PSU.
> 
> it seems to be the first thing recommended to try on several posts.
> Let us know if that does the trick.
> 
> Sent from my iPhone
> 
> On May 30, 2012, at 6:20 AM, "hazchem88" <analoguesolutions@...> wrote:
> 
> > 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!)
> > 
> > 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?)
> > 
> > 
> > 
> > 
> > 
> > 
> >
>