Error 10483: Seagate ST-177I doesn't spin at Power On (55SX / 70)
Time / Date / Config lost / Disk Error on Mod. 60/80
24 MB RAM installed - only 16 MB available (55SX,56,57...)
Unit does not run with cover removed (9556/57 9576/77)
Can access harddisk only with boot-disk (various models)
Installed Non-IBM SCSI CD-ROM under DOS and cannot access it
Misleading error-Code 0002 11CZ on Mod. 9556 / 9557
What's that "Key Symbol" I get after starting the machine ?
Screen stays black after going from Win95 to DOS
(Is to be continued recently)
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No. 1: Error 10483: Seagate ST-177I doesn't spin at Power On (55SX / 70)
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The Seagate ST-177I 60MB harddisk used on many Mod. 55SX (8555-061) and on some Mod. 70 (70-061) tends to hang at Power On.
This effect appears sometimes after the computer was off for a longer time. It is a result of adhesive-power between disk surfaces and r/w-heads. The surfaces are very plain polished and the heads really 'suck' on them. The spindle motor has not enough torque to loosen the platters from the heads.
There's no 'soft' solution. Several Power On cycles (20 sec. On, then 20 sec. Off) may start the drive ... or blow up the power-supply. And is no good treatment for the electronic components at all.
Alternatively: Unplug the system-unit from everything, shake it (up/down several times) then rotate the unit with a sharp kink clockwise some times. Plug it on again and Power on. The heads should have released and the drive spins up.
Don't lift the unit up on the frontside and let it crash back on the desk.
This method will definitely kill your harddisk very soon.
In either case you have badly treated your Harddisk and it is a good idea to begin backing up the data ... !
I have had good success with putting the system-unit on the rear seat of my car and drive to town, let the car on a sunny parking lot, go shopping, come back, drive home and plug it back on. Afterwards the drive runs again. Changes of temperature and the vibrations have caused the heads to release from the disk surfaces.
Disadvantage: my friend tried the same with his Mod. 55. Some guys broke his car open and stole the computer.
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No. 2: Time / Date / Config lost / Disk Error on Mod. 60/80
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Believe it or not: the above mentioned errors often have one common reason. Most recent effect is a frequent lost of configuration, internal clock shows totally wrong values after longer power off cycles or the disk drive has a lot read/write errors and installing a new battery or cleaning the disk-drive doesn't help.
Of course: it is a cleaning problem, but on the systemboard.
The area on the systemboard just under the power supply fan tends to get very dirty during the years. It is a good idea to fully disassemble the computer and blow through the power supply with a compressor and a fine nozzle.
Don't do this in your office !
Everything will get very dirty. It is astonishing how much dust can sit inside a single power supply.
Now look on your systemboard. It is awfully dirty, right ? I thought so. Take a brush and a vacuum-cleaner to get it properly clean. Look for dust and particles, which stuck between pins of the integrated circuits.
Just under the area where the fan sits, you will find (on a Mod. 80 board - after a close look)
- the 8042 systemboard controller - for i.e. the keyboard
- the MC146818A CMOS configuration storage and RTC
- the D7205 disk-drive controller
- the NS16550 serial interface controller
- a 32.768 KHz crystal for the RTC
- (sometimes) the 8259A Interrupt controller ...
All in all this is a very sensible area - and the collected dust is conductive in most cases and may cause the above mentioned trouble. Re-assemble the PC, start reference disk, set date, time and configuration again and try, if everything works again.
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No. 3: 24 MB RAM installed - only 16 MB available (55SX / 56 / 57 ...)
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In a brief: you cannot install more than 16 MB on machines with a 386SX-processor.
"Oh - sure, but my 9556 has a 486 !"
"Really ? Wasn't it a 486-SLC ?"
"Uhm ... er, yes ... think so !"
Gotcha. The 486-SLC is a Turbo-386SX. Ever wondered why they offer just a 387SX as mathematical Co-processor ? Now - that's the reason. The 486-SLC family has the internal 1st-Level-Cache like a 486 and some of the newer instructions, technically they are a 386SX. And these have only a 16-bit databus and 24-bit adressbus externally and can only adress 16 MegaByte.
24 adress-lines = 2 ^ 24 bytes adress-space= 16.777.216 bytes They are from the technicians point of view similar to the 286-processor, but can internally operate with 32-bits and 32-bit specific programs will run on them. They can even carry out 32-bit busmaster functions, unless they have only 16-bit MCA connectors (the short ones).
But the adress-space is limited to 16MB due to the lack of adressing lines.
Sad but true.
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No. 4: Unit does not run with cover removed (9556/57 9576/77)
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Certain Premium Line models 9556, 9557, 9576 and 9577 do not run with the cover removed.
This comes, because they have a security-switch built into the front of the base unit, which interrupts the power-supply. This little switch is easy to find - it is blue and sits somewhere left from the disk-drive bay.
It can be pushed with the finger gently upwards and to the inside - and the machine runs fine without the case.
No need to be afraid: both - the power-switch as well as the security switch - operate at low voltage. They switch only a +5V sense-line, not mains voltage.
But watch out: sometimes the security switch flips back after some time or when accidently bumping against the system. Result: the machine switches off immediately again. This is pretty annoying, when having just 95 percent from a software installed ...
The same switch is sometimes defective, after rude, careless people violently push the case over the machine - or stuff the machine into the cover respectively. It breaks and the machine won't power on.
If you are experiencing a machine, which does not power on, inspect this switch first, before you begin replacing parts like systemboard or power-supply.
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