On this mainboard ZD1 is missing, but it is the same as ZD2. I don’t see ZD6 here.

ZD7 is the one in the middle from the 3 yellow ones.

 

Xtuners,

Thanks for posting your results on Zener diode testing for the Speedo board. How did you test them? It looks like you replaced ZD3, ZD5, and ZD7 with new components. What part numbers did you use for those diodes?

Nice work!

 

Hi,

I used 32 Volt DC source, Multimeter and 1K resistor to test the zener diodes. The readings from the multimeter are accurate. The numbers on the diodes are also accurate and represent the breakdown voltage. They were not damaged. Replacing them did not solve my issue. What I want to do now is to place an order in some of the US online stores and get all the part numbers for you. I replaced all zener diodes, don’t mind the yellow color, normally they are all orange.

 

Has anybody been able to find a replacement for the lcd???

 

@Xtuners,

What part numbers did you use for those replacement Zener diodes? That may help others who need to replace damaged ZD3, ZD5, and ZD7.

@Angel Guard Racing Team,

It is very unusual for the LCD to go bad. There are no known replacements. However one could cannibalize an LCD from another speedo.

 

It was the polarizing film... I ordered a nintendo gameboy polarizing film to see if it works...

 

I am helping a friend with his odometer, I replaced all caps but nothing. Then I noticed only 1v coming out of ic2 I replaced ic2 and it started working... After a few hours odometer went blank again... Any ideas or pointers?

 

IC2 is still good but There is 0.15v getting to the odometer eeprom IC3 vcc (leg 8) those eeproms run between 3.3v and 5v.

C1, C4 abd C6 are getting 0.15v also.

TR5 looking at the flat side from left to right I get 0v, 0v, 0.15v.

That's all I have been able to test after odometer went out again because of lack of time.

I am testing on bench with power supply set to 12v, using D3 for 12v input, and PGND and ILL for gnd.

 

Fixed it...

 

Can you update with how you fixed it?

 

can you buy this piece separate ? Mine broke… seems like the old owner was to harsh with it. Now the km/h is more wrong Than before and I can’t adjust it

 

Go back a few posts: https://www.rx7club.com/3rd-generati.../#post12372695
A higher quality replacement for the variable resistor would be a Bourns 3296X-1-204-ND available from the likes of Digikey etc. You will need to bend the legs to make it fit.
Calibration? This guide may help: https://www.rx7club.com/3rd-generati.../#post12620122

 

I missed that… thank you so much ! I ordered 3 and will try it out. Really appreciate it ! If it doesn’t work then I can always send it to someone.