Re: Toshiba 3450 Fax - need Service Manual



Cobalt wrote:
> What kind of past history before the fail? Lightning, dropped, in storage
> for years or found it in the dumpster?
>
> You could have bad solder on the main CPU chip....or even on the display,
> especially if there are signs of a liquid spill. Try flexing or vibrating
> the board for possible intermittents. Can also try powering up the unit
> while holding the send key, or other keys in hopes it does a system reset,
> in case something got corrupted. Sometimes there is a battery too that is
> soldered in and can cause loss of cpu operations.
>
>
> <michael.w.appenzeller@xxxxxxxx> wrote in message
> news:1119402330.265587.65370@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
> |I need a service manual or at least schematic for the main board
> | of a Toshiba 3450 Fax machine.
> |
> | Not available from Tritronics, Herman's, or Vance-Baldwin -
> | apparently Faxes are made by a different division of Toshiba than
> | their A/V stuff. The model was not listed on any of the on-line fax
> | parts dealers I tried. Calling Toshiba directly, I just got the
> | runaround, just being told to call different numbers - no one
> | actually said they didn't have the manual - just didn't have a clue
> | as to how to get it. I have a collection of 8 or 9 different
> | phone numbers I was passed around to over a 2 day period.
> |
> | Problem with the machine is it's basically dead. Thought it would
> | be a simple power supply problem, ESR'd the caps in the PS, found
> | an open 0.33 uF electrolytic, replaced with three 0.1s. Machine
> | still dead, but have +5, +/-12, and +24 volts from PS. One output
> | is relay switched, and never turns on. I don't know if there
> | should be any additional output voltages from the PS. Have clocks
> | and data activity on the uP (Z8002), but nothing on LCD except a
> | faint row of blocks on the top line of the display, no other signs
> | of life.
> |
> | Mike
> | WB2ME
> |
Cobalt,

Thanks for the reply. The machine in question was basically
intercepted
on its way to the dumpster, then in storage about 2 years.

The unit doesn't appear lightning damaged, it has rather impressive
surge protection built-in, including low current fuses on the phone
line input, and the power supply appears functional. I don't know
if all the voltages are present, though. The PS plugs directly onto
the motherboard, and is inaccessible when installed (component side
of PS board facing into machine, solder side covered by sheet-
aluminum heat sink). I didn't power up the supply outside of the
machine as I was afraid of damaging it without a load. Now
that I've powered it up in the machine, and have voltages at
some of the connector pins, I know what pins have what voltages,
so I may pull the PS and power it up with a load on the 5V line.

There is a ni-cad battery (3 button cells in series), and it was
dead. I charged it with my bench power supply, and although it
won't hold a charge, it gets 5V across it when the machine is on.
I doubt they would have used a ni-cad battery to back up the
unit's operational firmware- probably just holds user settings
and keeps the clock running. There is a UV-EPROM in there, which
probably has the operating firmware.

The machine doesn't appear sensitive to vibration, and the main
board is a very rigid 4-layer board that doesn't flex, soldering
looks excellent. I tried resetting the CPU by grounding the
Reset pin on the uP - if that doesn't reset it, nothing will.
Although this is a compact, entry-level Fax, comparable in
features to the $99 specials in the office supply superstores,
the electronic & mechanical build quality is impressive, like
what you'd see in high-quality pro or industrial equipment,
so it's worth putting a little effort into fixing it,
just need more information.

Mike
WB2MEP

.

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