[Search for users]
[Overall Top Noters]
[List of all Conferences]
[Download this site]
| Title: | Atari ST, TT, & Falcon |
| Notice: | Please read note 1.0 and its replies before posting! |
| Moderator: | FUNYET::ANDERSON |
|
| Created: | Mon Apr 04 1988 |
| Last Modified: | Tue May 06 1997 |
| Last Successful Update: | Fri Jun 06 1997 |
| Number of topics: | 1433 |
| Total number of notes: | 10312 |
1089.0. "System Woes - is it time to find a repair center?" by DECWET::HASLOCK (Opinions - Worth what you pay) Wed Mar 13 1991 17:15
Before I moved, I upgraded by 520 STfm (Rev D) to 1 meg.
Most of the time it worked but sometimes I would get bits dropping out on the
screen, starting at the top left but spreading with time. When bits start
dropping out around text, white pixels following black pixels stay white (It
is a mono monitor and I use black text on a white ground).
When I unpacked the machine this fault was still present. Last night, I took
all the screens off and pushed on all the socketed chips and it was fine
until I put the screens back on.
Two more problems showed up last night.
1) Turning the system on did not result in the floppy turning on
although the system power light went on.
This problem went away after I stripped the machine down for
the second time although I did nothing to fix it.
Since this was happening in the time of maximum power consumption
and I live out in the country, I was wondering if low supply
voltage might cause this.
2) The screen looks like horizontal hold has failed but only every
2, 4, 8, 16 lines and only some of the time. This is not the
monitor because I plugged into my TV set and got a similar picture.
That is, each group of 16 lines shows up half an inch to the left
of the previous group. Within each group, the lines jitter between
being an intact block and having each successive pair of lines
shifted left.
I haven't tried pulling the machine apart again since this problem
appeared.
Any suggestions will be gratefully received.
| T.R | Title | User | Personal
Name | Date | Lines |
|---|
| 1089.1 | flaky ST | KORG::MISKINIS | | Wed Mar 13 1991 18:42 | 9 |
|
WOW, I wish I had some advice for THAT one.... Whew....
If worse comes to worse, I think Atari will swap the mother board
for the low, low, price of $375!
_John_
(Who though he paid too much when it was $125!)
|
| 1089.2 | You needed a Mega STe anyway, didn't you. | PRNSYS::LOMICKAJ | Jeffrey A. Lomicka | Thu Mar 14 1991 10:43 | 26 |
| '520 memory upgrades do that sometimes. I have some theories, none of
which are confirmed as real problems in real systems:
- It's hard to get power down that narrow power cable between the power
supply and the CPU. Check the power for ripple and noise at the CPU
end. Perhaps a larger decoupling capacitor on entry to the ST board
itself (say 50�f) and also on entry to the expansion board (say 20�f)
woudl help.
- Something is being pinched or shorted by the process of sandwiching
the machine into the RF shield. (Given your description, this is likely.)
- The impedance of the interconnect between the expansion board and the
CPU board is adversely affecting the signal integrety of the address
and/or data bus to RAM. Perhaps an inevitable side effect of the design
of the upgrade. If you have a hf 'scope, check for undershoot on the
expansion RAM. Not sure what the fix would be. Damping resistors and
clamping diodes? Not generally the bailiwick of most software types.
- '520 memory upgrades just don't work. (There are times that I believe this.)
- You need an excuse to get a Mega STe...
If you lines were VERTICAL instead of HORIZONTAL, I could point you at a
bad RAM. Horizontal lines are more indicitive of a power or
interconnect problem than a component problem.
|
| 1089.3 | Mistaken assumption | DECWET::HASLOCK | Opinions - Worth what you pay | Thu Mar 14 1991 12:55 | 9 |
| The memory expansion was 'plug in the chips' to the motherboard not 'insert
expansion board with added chips'.
I wish I could justify spending money on an STe, but the house needs a garage
first.
I'll try didling with the power supply and see what happens.
Thanks for reply.
|