808 Drivers (was: Injector Impedance how low can i go...)

[Steve Lamb]

>        I recently discovered that the "808" seems to have the ability
>to drive a couple of low impedence injectors in peek and hold mode.
>There is provision already on the PCB to use the existing saturation
>injector driver in peek and hold mode by,
>
>           1) Disconnecting the wire D10 at the ECU. This is the
>injector driver's ground circuit (source) which goes to engine ground.
>
>           2) Put jumper wire between D9 and D10 on ECU, this will put a
>0.1 ohm resistor which is already on the PCB in series with the injector
>drivers source and ground. This 0.1 ohm resistor is used to sense
>current for Peek & hold.

I have a few spare 808's lying around and one of them is a but suspect so
I've stripped out the heatsinks, etc to get a closer look at the driver
chips and so on.   In the 808, pins D15 and D16 are the injector signal
outputs and they are jumpered at the PCB.  Doing a bit of simple tracing I
found that D15/16 are connected to a 3 pin TO220 (?) style component
labelled:

M9707
R208

One of the other 'legs' of this component is connected to PCB earth (and
thereby, pin D10), while the remaining 'leg' can be traced (via a 1.2K
resistor) to a large, square flat IC with multiple pins on each side (PLC
style ??) which is labelled:

Korea
519K  9211
2064  16079435
F21

I'm assuming that the first component (3-leg) is the power switching MOSFET
(?), while the second is the driver, amongst other things.   This appears
to square with Bruce's indication that the 808 only has one driver circuit

Checking Pin D9 I found that it appears to be directly connected to the
earth 'leg' of a 5 pin component (again TO220 ??) right next to the 3-leg
mentioned above.  This component is labelled:

[Motorolla trade mark]
16156085
QQQ207

It could well be that there is a 0.1 Ohm resistor in the line here as
Richard suggests, but I do not trust my DVM at this level.

Anyone have any info on what the above component ID's actually mean and
whether the suggested P&H mod is likely to fit in with the above
configuration ??

I can disassemble this spare one a bit further if needed.

BTW, there are also apparently two 'versions' of the 808 ecm - early and
late (duh !!).  They are functionaly identical, but the late style has a
different PCB design, with some components in a completely different
location on the board compared to the early version.  Apparently early
808's suffered from power supply problems - and I know a few people with
Camira's and early Commodes that needed replacements.

Cheers










Steve Lamb
Department of Defence, DSTO
Aeronautical and Maritime Research Laboratory
506 Lorimer Street
Fishermans Bend  VIC 3207 Australia

Tel: +61 3 9626 7525
Fax: +61 3 9626 7089

IZCC #180