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From: iav1917%ritcv@cs.rit.edu (alan i. vymetalik)
Newsgroups: comp.sys.dec.micro
Subject: Re: Rainbow boot error
Message-ID: <1644@cs.rit.edu>
Date: 23 Feb 90 06:22:59 GMT
References: <359@latvax8.lat.oz>
Sender: news@cs.rit.edu
Reply-To: iav1917%ritcv@cs.rit.edu (alan i. vymetalik)
Organization: Rochester Institute of Technology, Rochester, NY
Lines: 47

In article <359@latvax8.lat.oz> CCPN@latvax8.lat.oz (Paul Nankervis) writes:
>I have a RAINBOW 100B which fails to boot. It displays ERROR 18
>and has all the diagnostic lights on except 5 & 6. I have a set
>of RAINBOW 100A documentation which says that this is a Z80 CRC
>error. Does anyone know what causes this error (eg Z80, RAM, ROM, etc),
>or do I have to throw away the motherboard?
>
>Paul Nankervis
>CCPN@LATVAX8.LAT.OZ
>La Trobe University
>Australia

   Yikes!

   I've never seen this error before and I've seen a bunch of them,
   including a blown-up motherboard.  I checked my doc set for the 100B
   (The Technical Manual Addendum) and you're correct on the error code.
   How often does it appear?  Have you turned off/on the Rainbow, let
   it sit off, and then test boot it again?  Does it ever boot up all
   the way?  It it ever boots up, do you have any diagnostic software
   that you can run?

   Suggestion:  If you feel comfortable with electronics, I would suggest
   removing the motherboard, clean away dust by blowing and wiping with
   an anti-static electronic cleaning brush (or air spray can).  Then
   check to make sure that all chips (especially around the Z80 CPU)
   including the Z80 are properly seated. You may want to partially
   remove the Z80 chip and reseat it.  Oxidation may have set in and
   a bad contact is occuring on the pins.  If it still fails after
   cleaning and reseating everything and connecting it back up, then
   you're going to need service because one or more chips have failed.
   You'd need an oscilliscope and schematics to track it down.  I'm
   surprised that a 100B board has died.  Most of the dead ones I've
   dealt with were 100As.  

   Good luck.

   Enjoy,
   alan

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   Alan I. Vymetalik, 2244 East Avenue #5, Rochester, New York, 14610-2518
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