Replacing Odometer Screen

[JoeLanger]

I wouldnt worry too much about the mileage, just record the two numbers when you come to sell.
Mileage means nothing on these cars

 

[JagKing]

Out of interest, how did the other solution go and what was it?

 

[Wake]

Out of interest, how did the other solution go and what was it?

Sorry for the delay in getting back to this. I managed to get another cluster with very similar mileage to mine (a little bit more). Haven’t had a chance to fit it though due to work!

 

[JagKing]

Ah, nothing fancy then was hoping someone had told you where to get screens or something. Regardless, sounds like you're going to be sorted.

 

[BenLewisMAV]

Glad you managed to find one with similar mileage, that's a result.
If you hadn't, my preference for fixing it would be to get hold of a 2nd hand unit and switch over the mileage chip (8 pins circled in orange on the attached images). Changing the screen involves desoldering the 40-50pins highlighted in red, fairly tedious.

It is possible to reprogram the chip when you know which registers to change, (essentially clocking it) but it's a decent amount of effort when it's just as quick to desolder/resolder the old chip over - you normally have to remove the chip or at least desolder a couple of pins to reflash the eeprom anyway. If the original mileage chip is damaged I guess that's only situation where it'd be warranted, but they're usually pretty robust.

Getting hold of replacement screens would be nice! Because of the additional features ('A, B, miles, kms') I guess it's a custom job for the RX7 - unless anyone can find the display being used in another vehicle? Perhaps we could start looking into a limited run of LCD's if enough start failing?

 

[Wake]

Glad you managed to find one with similar mileage, that's a result.
If you hadn't, my preference for fixing it would be to get hold of a 2nd hand unit and switch over the mileage chip (8 pins circled in orange on the attached images). Changing the screen involves desoldering the 40-50pins highlighted in red, fairly tedious.

It is possible to reprogram the chip when you know which registers to change, (essentially clocking it) but it's a decent amount of effort when it's just as quick to desolder/resolder the old chip over - you normally have to remove the chip or at least desolder a couple of pins to reflash the eeprom anyway. If the original mileage chip is damaged I guess that's only situation where it'd be warranted, but they're usually pretty robust.

Getting hold of replacement screens would be nice! Because of the additional features ('A, B, miles, kms') I guess it's a custom job for the RX7 - unless anyone can find the display being used in another vehicle?

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Hey thanks for that man. The cluster I got has about 1750 more miles than my original. If the car had 60k+ on it I wouldn’t be bothered but it’s only done about 36k so I might have a crack at this!

 

[BenLewisMAV]

Hey thanks for that man. The cluster I got has about 1750 more miles than my original. If the car had 60k+ on it I wouldn’t be bothered but it’s only done about 36k so I might have a crack at this!

Sounds good, use a decent (40-50w+) solder iron in short, sharp bursts and a solder sucker (not solder wick) to avoid putting too much heat into the chip. Something like this for £1.19 (!) would do, branded would probably work/last better.

If you find you have a stubborn joint then melt some new solder into it first, and allow it cool down between attempts.
Some fine tweezers also come in handy to manipulate the chip legs away from the residual solder remaining in the hole - ESD Tweezers.