4 Mar 2007

Emulator 2: channel down

Mostly due to a faulty S3528 on the channel board (analog)

If you look attentively, you will notice that the board is arranged in
"vertical" rows (assuming you are in front of the machine), one row for
each channel output.

Change the faulty S3528

Thanks to Dr.C for providing this info.

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Emulator 2 memory error

A "craaak" in the sound, or an erratic behaviour.

Explanation : Some of the sound memory is used as "scratchpad" memory, for the system.

The memory is arranged, if I remember well, in a block of 8x8 chips (unless
you dont have the piggyback additional memory board).

First : take away ALL the memory chips by remembering their location and
intervert them.
Is there a change ?

If the machine boots okay now, just sample music at maximum length (all the
memory).

Listen to it. Is there a "crakkk" sound somewhere ? How long does it take
to come ?

Now, intervert one quarter of the memories to another quarter

Sample again.

The cracckkkk sound has changed, in terme of the moment it occurs ? No ?
This means that the two quarters you have sawpped around are good chips.

Now, locate another quarter of the the (one of the two you didn't move) and
swap the two halves of them. Location of the crackk has changed ? Yes ? You
are close to it. Now, swap the half of the quarter in two halves. Etc...

At last, you will find the faulty chip. In teh WORSE case, it will take six
operations to find a faulty chip out of 64 chips and 16 operations to find
a faulty chip out of for 65536.

Now, finding a chip somewhere is gonna be something else...

Thanks to Dr.C for providing this info.

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Emulator 2 start problem
The floppy reader clicks three times, the machine displays "This will take
a while" or "Boot in progress" and sits there forever.

BE CAREFULL, THIS IS DANGEROUS.

TAKE AWAY the power plug from the machine.

Open it and take the power supply away.

You will see that the connector (the one with the yellow, red wires that
distributes the power to the boards and the floppies) may be brown, burned
at the location of the yellow wires, wich is the +5 volts.

Idealy, this connector shoud be changed. If you cant, just clean it by
putting some contact cleaner.

Power supply, now...

If you take an attentive look to the solder side on the connector pins, you
will find out that the solder is crackeled.

By using a solder pump, take away the bad solder and take away the connector.

Using a blade, scratch the varnish off the board (near the holes of the
connector) in order to increase the surface of the soldering on the copper
layer of the board.

Clean everything.

Clean the pins of the connector.

Solder the connector back in place, put A LOT of solder but be carefull
that the solder doesn't come in contact with the right angle metallic plate
when you put the power supply back in place onto it and as well, be sure
you are not shorting some connector pins !

VERIFY EVERYTHING before soldering, while soldering, after soldering and
verify your verification !!!

Put the power supply back in place, do not forget to put back the two wires
of the voltage selector, neither the connector with the wires.

CAUTION : an "unloaded" E2 power suplply wil BLOW INSTANTLY if you forget
to put back ALL the connectoirs in place.

It will work for years then.

Thanks to Dr.C for providing this info.

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EIII: no more disk? Solution

The disk is Okay but the machine scans SCSI channels, or tells : "No disk",
or whatever...

Go to the processor board, take away and put back the NCR5380 in place. It
works 50% of the time. Or change it.

If the Emu is connected to external SCSI devices, touch the flat cable
(inside) going to the SCSI connector. If its hot, your external devices are
ripping off the emu and this wall happen again !

Thanks to Dr.C for providing this info.

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EIII dead CPU board? Solution
A dead CPU board is very often due to a chip located on the front border of
the CPU board (the second one starting from the top.

Its a 74HCT244, labeled (if I remember well) : IC240. Its anyway easily
recognizable ; it has a few wires modification on the solder side

Change it to an 74LS244, taking great care to take note of the wire
modifications and installing the circuit on TWO HIGH QUALITY tulip single
on line (cutable) connector.

The change from HTC to LS is okay for this chip. Don't change them all !!!!!

Thanks to Dr.C for providing this info.

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EIII won't start up? Solution
If one formats and install a disk in an EIII, or just maybe a system
install, the disk will go round and round, scanning the channels without
being able to boot.

Its a bug.

When you format and install a system, once you have finished and BEFORE
restarting the EIII, just save a bank, even a blank bank, it has no
importance, the idea is to have AT LEAST on bank, even empty, into the
directory, or the machine will never start when you power it up again.

By following these insructions, the machine will find an empty bank, start
on it, and here we go !

Thanks to Dr.C for providing this info.

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