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Old 14th March 2019, 23:50   #11
marinabrian
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The rev counter is the problem Brian.One moment it is not registering,then it shoots up and the next moment it is readung low.
Ah I see, then if you swap the EEprom from the original speedo to that of the "new" one, all the information will transfer over.

I don't know if you've delved inside one of these before, but no matter, if you want I can do the job for you.

It's been a while since I've had one of these apart, but it's like riding a bike, you tend not to forget

Brian
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Old 14th March 2019, 23:59   #12
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Ah I see, then if you swap the EEprom from the original speedo to that of the "new" one, all the information will transfer over.

I don't know if you've delved inside one of these before, but no matter, if you want I can do the job for you.

It's been a while since I've had one of these apart, but it's like riding a bike, you tend not to forget

Brian
Thanks Brian.I think thats what Nick at Austin Garages was intending to do, but he said having had one apart recently from a late facelift car it wasn't possible,something to do with the rev counter and speedo sharing some inaccessable component (I think).I'm having the clusters swapped on Saturday and will tell him what you and Phil have said.I'll get back to you if he can't sort it if thats ok?
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Old 15th March 2019, 00:03   #13
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Thanks Brian.I think thats what Nick at Austin Garages was intending to do, but he said having had one apart recently from a late facelift car it wasn't possible,something to do with the rev counter and speedo sharing some inaccessable component (I think).I'm having the clusters swapped on Saturday and will tell him what you and Phil have said.I'll get back to you if he can't sort it if thats ok?
No bother Mick

The chip in question is an 8 pin soic and looks like this.



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Old 15th March 2019, 00:06   #14
VVC-Geeza
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No bother Mick

The chip in question is an 8 pin soic and looks like this.



Brian
Thanks Brian I'll let you know how we get on.
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Old 15th March 2019, 13:51   #15
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This is the unit.





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Old 16th March 2019, 09:47   #16
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Yes, that's dead easy to do Mick, the dials etc complete with their motors unplug from the PCB, allowing complete access to the PCB.

In many ways they are easier to disassemble than a 75 IPK, as the needles do not require to be removed from the faces.

Once the fascia is opened up, you will see the temperature and fuel gauges are separate from the rev counter and speedo.

The screws securing the mylar circuit to the back of the white plastic part, and then the PCB are removed, allowing the removal of the rev counter speedo, then once out of the plastic part, the PCB can be gently prised away from the speedo and rev counter stepper motors, which will leave eight "prongs" sticking up from the PCB, the interconnects between the motor and PCB are designed to separate in this way.

You can then exchange the 93C46 serial eeprom

Hope this helps, or if you don't fancy doing the job, as mentioned you can bung them in a box and post them up to me and I'll sort them for you

Brian
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Old 16th March 2019, 18:08   #17
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Hi Brian,I cleaned up the body earth as suggested but unfortunately no joy with the rev counter fault. Thinking about it if you tap the dash binacle over the instrument pack it normalises the rev counter to read correctly for a short time,this suggests a fault with the instrument itself.
I'll get both units posted off to you at the end of next week.Can you pm me your details please? Many thanks.
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