ttam@cory.Berkeley.EDU (Tony Tam) (06/04/91)
I NEED HELP!!! I was trying to connect an RGB monitor (IBMPCjr) to my A1000 and I blew something on the motherboard. What I did: o I accidentally let the Horizontal Sync (+2.3V) touch the ground pin on the A1000 RGB port and now the A1000 does not work. No picture and no boot. What blew: o I think one of the 74H74 chips (U8I) got fried but not too sure. o Maybe also a diode ??? (C62) got fried. Needed: o Anyone have any ideas on what may got blown? o Is there a service center for repairing A1000 motherboard cheap? o Anyone has a spare A1000 motherboard lying around and want to sell? o Any suggestions other than trash the thing and sell the acessories. o Does the Phenyx or Rejuv. board replaces the motherboard? o Can I buy just the A2000 motherboard? Thanks Alex Davis ttam@cory.berkeley.edu
Edward_Braswell@a68k.UUCP (Edward Braswell) (06/07/91)
Well, I just happen to have a spare motherboard lying around that I could
part with. Let's see, if you shorted the Hsync to ground, it comes directly
from Agnus (no buffering, except for a 47 ohm resistor, which "should" have
kept agnus from frying for a momentary short, but may not have). Is it
possible that you shorted something else to ground as well? (like the +5
volts on pin 23?)
By the way, with the RGB hack, were you planning on using something like a
7404 inverter to invert both the H Sync and V Sync lines? They will need
inverting in order to drive either an RGB or RGBI monitor (I know, since I've
run both off of an amiga (at once!). The RGBI mode is wierd, as it uses the
least significant bit of the BLUE color to drive the intensity line, which
means when the blue register is 0000, the Intensity is 0, 0001 means
intensity is 1, 0010 means 0, etc.. so, when you're in preferences, and drag
the blue color slider back and forth, you can see the intensity go
hi/lo/hi/lo. Kinda neat, if sleazy on commodore's part).
Whoops, got carried away. But back to the motherboard: Phoenix _IS_ a
replacement A1000 motherboard, so if you want to get a 1 Meg Agnus for your
A1000, it might be the way to go. The Rejuvinator just attaches like the
current daughterboard (I think) only bigger, with pins running to the sockets
where Agnus, Paula, and Denise currently reside (or so I've heard it
described). If your only problem is a bad Agnus, it would solve the problem.
Anyways, so.. if the ONLY thing you did was short HSync to ground, then
theoretically, the only thing that should need replacing is the Agnus. You
might want to look into just "borrowing" one of them and seeing if that takes
care of things. If you can't get one locally, I suppose I could send mine,
or if you can afford it, I could just ship the motherboard. However, what's
a fair price for a motheboard? I'm not sure, but would think somewhere
around $100, possibly a little less, would be about right. Last I saw, a
used, beat-up A1000 was going for around $175 or so.
But I'm willing to discuss alternatives/trade/whatever.
Your Move...
Ed Braswell of Tucson AZ.
(If you want to get ahold of me soonest, and don't mind long distance (or
have StarLink, but I don't think PCPursuit does Tucson), I run a BBS at
1 602 795 0161 with hours nominally from 6PM to 7 AM Mountain Standard
Time (NOT daylight, as AZ doesnt do daylight savings!). If you call the
BBS, just leave a note to the sysops when you log off (you'll get the
option).