Oki 320/1 Turbo -- Revision I0

A revision 'I0'^[1] 320T is in the shop for a warranty repair. Oki has completely redesigned the printer's electronics in this revision. There's a switchmode power supply now, so the transformer is no more. Here's a view of the back of the printer.

The change lever position detection switches are now on their own little PCA tacked onto a bracket at the front of the power supply PCA, like so.

Part Numbers

Main Logic PCA: P/N 55117951 -- for revision I0. [TUESDAY, FEBRUARY 14, 2012 -- This may be in error. To be determined.]^[2]

Power Supply: P/N 55118051 -- for revisions E0, H0 and I0.

Main Logic PCA Replacement

When removing a PCA, the bracket around the interface option slot can remain in place -- just remove the one screw that's high up on the main logic PCA's bracket plus, of course, the two screws at the bottom of the PCA.

A replacement main logic PCA comes without the sheet metal bracket on it; the old one has to be transferred over. 'Easiest way to do that is as follows:

1) Remove wire bails and bracket from old PCA.

2) Remove wire bails from new PCA.

3) Install bracket and wire bails on new PCA.

4) Install two screws, adjust bracket position A/R and tighten screws. (The bracket has a slightly deranged position adjustment latitude. Get the USB connector opening centred and you'll have it right.)

When installing the PCA, jam a business card under the platen to hold the paper-out sensor actuated so its flag will be clear of the optical sensor on the PCA.

The lower rear end of the PCA sits in a sheet metal 'cradle', like so.

Cover Replacement

The wire bails and all the sheet metal make getting the top cover in position for closure a bit finicky. Relax and take your time. It's one of those chores that proves the truth of the saying, "haste makes waste".

Serial Interface Option

The old 'LXHI' serial I/F card won't work with this new revision. This post has information about the new serial I/F.

This Printer's Problem

The machine would come ready and load paper, but carriage motion was weak and halting. Eventually, it would stop with a 'spacing alarm' (ALARM flashing; HSD & PROP lit). The space motor felt fine. 'Likeliest culprit appeared to be the main logic PCA, and that turned out to be the case.

The New Technology

The following is from an Oki bulletin, Document #4096. (Pay attention; this is the sort of crap that will be on the test, for certain.)

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"What is SoC?

System-on-a-Chip or System on Chip (SoC or SOC) refers to integrating all components of a computer or other electronic system into a single integrated circuit (chip). It may contain digital, analog, mixed-signal, and often radio-frequency functions – all on a single chip substrate.

A typical SoC consists of:

One microcontroller, microprocessor or DSP core(s). Some SoCs – called multiprocessor System-on-Chip (MPSoC) – include more than one processor core.
Memory blocks including a selection of ROM, RAM, EEPROM and flash.
Timing sources including oscillators and phase-locked loops.
Peripherals including counter-timers, real-time timers and power-on reset generators.
External interfaces including industry standards such as USB, FireWire, Ethernet, USART, SPI.
Analog interfaces including ADCs and DACs.
Voltage regulators and power management circuits.

These blocks are connected by either a proprietary or industry-standard bus such as the AMBA bus from ARM. DMA controllers route data directly between external interfaces and memory, by-passing the processor core and thereby increasing the data throughput of the SoC.

In short, increasing chip integration helps to reduce manufacturing costs (due to fewer packages in the system) and to enable smaller systems. SoC designs usually consume less power and have a lower cost and higher reliability than the multi-chip systems that they replace."

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There you go. Aren't you glad you read all that? That's the sort of information that helps you fix printers, alright.

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Notes:

[1] That's 'eye zero'. Trust Oki to come up with the most ambiguous character combination possible for a revision level designation.

[2] MONDAY, FEBRUARY 27, 2012: Supposedly, the same PCA is used for both the 320T (narrow) and 321T (wide) models. The PCA as it's received has 321T functionality. If it's installed in a 320T, the 320T will think it's a wide carriage machine and act accordingly. Running the rolling ASCII self test will result in the carriage slamming into its right side stop.

When installed in a 320T, the 'Page Width' item in the Menu's rear, bottom and top feed groups must be set to 8" (the factory setting is 13.6").

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