aduncan@rhea.trl.OZ.AU (Allan Duncan) (06/21/91)
I am having trouble getting the Super Agnes to work with the rest of the
system. It is a very iffy failure that seems to involve the other
special chips (it usually involves the rendering of a menu or requester
in Pro Page).
Has anyone got the details of what was done between the board revisions?
Mine is about 4.2 or 4.3 (I'm not pulling the lid off just to look while
on-line:-))
I had one suggestion of "a 1K resistor between pins 28 and 40", but
didn't get the chips that these were attached to!
Pin 28 of Agnes is the C1 line, no pin 40 looks likely.
I have got the above problem even on just the floppies, without the
venerable C= 2Meg board, hard disk, and 2088, although not as severe.
Allan Duncan ACSnet a.duncan@trl.oz
(+613) 541 6708 Internet a.duncan@trl.oz.au
UUCP {uunet,hplabs,ukc}!munnari!trl.oz.au!a.duncan
Telecom Research Labs, PO Box 249, Clayton, Victoria, 3168, Australia.bryan@cs.utexas.edu (Bryan Bayerdorffer @ Wit's End) (06/22/91)
In article <1991Jun21.021132.23327@trl.oz.au> aduncan@rhea.trl.OZ.AU (Allan Duncan) writes:
=-
=-Has anyone got the details of what was done between the board revisions?
=-Mine is about 4.2 or 4.3 (I'm not pulling the lid off just to look while
=-on-line:-))
=-
Here's the short version, summarizing the procedure given in Issue #26, section
3-2.1 (Jul-Sep 89) of the Commodore service technician's update, "TechTopics:"
A2000 field upgrade to rev 4.5:
1. Remove if installed: R901, C917, C902, C910, C911, C905, C908, C230, C240
2. Install 1.3 Kickstart ROM
3. Install RP904, RP905, RP906 only if U205 and U206 are 74HC244 type ICs
4. Add .01uF ceramic cap on solder side from pin 12 of J300 to nearby ground
pads.
5. Add 3.3K ohm, 1/4W resistor across pins 11 and 20 of U605. [Note: Dave Haynie
recommended 1K ohm resistor in a previous article]
6. Add 470 ohm, 1/4W resistor from cathode of D800 to second pad from the left,
under CN605. (Already installed as R1000 on rev4.3 and above)
7. If R5719 not present, add 470 ohm resistor between Vcc and CPU side of R106.
Use pad located to the right of U100, and the pad on the ground trace running
under pin 14 of the 68000.
8. Replace Toshiba GARY (U102) with MOS GARY.
DISCLAIMER: While making these modifications eliminated some problems with my
A2000, I take no responsibility for the results obtained by anyone else
following the above procedure, nor for any inacuracies or errors I may have
introduced. For a full description of the procedure, obtain a copy of
TechTopics #26 from a Commodore dealer. In addition, it may be that the
procedure was revised in a later issue.
That said, let me mention that the most important step in *my* case appeared to
be the replacement of the Toshiba GARY with a MOS GARY.