Timbo
Club Member
Having spent Sunday recommissioning my broken rev counter I thought I would share the results.
Basically the existing unit was faulty and various attempts to trace the fault from the coil though to the rev counter ended with the disassembly of the tachometer and the acknowledgement that the old electronics were past their best.
So I embarked on a search for a solution and came across a company called SPIYDA who create a simple system that takes any type of input, converts it to a signal that then feeds the movement of the tachometer.
It claims to work with any rev counter and is calibrated using a rather intriguing series of WAV files which you download to your phone (or audio player)
You then play the sound waves into your Tachometer via the black box of tricks via a supplied cable and adjust the revs according to the predetermined file selected.
Not revolutionary but it works and unless your actual Tachometer movement is broken saves a good lump of cash! So here's how I did mine.
Apologies in advance for the lack of pictures as it is my first proper 'doing something' post here.
The small black box of tricks arrived Saturday, so Sunday I whipped out the Rev counter and dissembled it (I won't go into the details of this as I know there are many comprehensive examples on here)
The important wires to either re-purpose or divert are marked in the picture below.
The Black Earth wire also grounds the lights, so needs to remain.
The Green wire is a live feed for the Rev Counter only, so this will be diverted to the Black box as no Live feed is required from the box to the Rev Counter. Instead I repurposed this insulated into one of the two outputs from the black box that feed the Tachometer movement.
The Red wire with Black stripe is the output from the coil, via in my case the original electronic ignition module.
Again, this will no longer go directly to the rev counter but instead feed the black box, which in turn sends two outputs to the Rev counter.
It is worth pointing out now that when tracing this wire, in all Datsun 260z wiring diagrams this wire is Blue, which this one is also, right up to just a few inches further down the loom form this point. No idea why it changes colour to Red & Black.
Cables disconnected and casing removed.
Side on picture of old, bare electronics with casing removed.
I then got the unit on my rather crowded bench and unsoldered the Black and white wires attached to the magnetic movement of the tachometer from the circuit board underneath it.
Then, leaving the Face of the dial and needle in place I undid the two brass screws that hold the circuit board onto chassis of the unit.
Once the screws were removed I cracked the circuit board into two pieces in order to remove it without the need to remove the dial or the needle which can itself result in breakages.
Then to connect the White and Black wires to the two corresponding terminal in the SPIYDA box.
No frills here. This is a Black Box with a processor and a single tranny. Nevertheless it's fascinating to see how the jumbled collection of resistors, capacitors and other components from the original board are replaced with this......................
It does come in a Black box and measures roughly 10cm x 5 cm, so is easy to mount under the dash close to the back of the original Tachometer assembly. But ultimately you have to create your own cabling (it comes with just the 3.5mm audio cable for connecting to your phone) so can in theory mount it in the trunk if you so wish.
So..........this is where my enthusiasm to get the job done overtook my patience in documenting my progress with pictures. Suffice to say I connected the two output wires from the Tachometer movement to the two relevant terminals in the Spiyda Box of tricks. So further imagery is limited.
However you can see below my initial connections from box to Rev counter for testing.
Just the two wires from the old tachometer movement to the Spiyda box (Green and Yellow)
When I reassembled the backing and case, I actually soldered the two wires from the movement to
a) The original Green LIVE input to the Tachometer - now no longer used so a useful terminal
b) The original bullet shaped input that used to receive the signal from the coil (The old Red wire with Black stripe)
c) Finally the original Earth was connected back to the case of the Tachometer, with a split running to the Earth of the Spiyda box, as this Earth also feeds the indicator and dash lights
The Live for the Spiyda box is fed by the Original Green LIVE wire that used to run to the Tachometer.
Wiring diagram form the Spiyda for the box below for easier reference;
And finally, pictures of my Hanging Spiyda box before mounted. Exact location TBC, but it is smaller than a Gnat's rucksack so should be easy to find somewhere. Mañana.....
And last but not least, one working rev counter.......the movement of which I of course cannot post as part of the thread, but there is a still image and if you click on the link below it, you will be taken to a short burst of action on YouTube...........................
I didn't go into the depths of calibration through the downloading and playing of WAV files, but suffice to say it was straightforward as it comes with the 3.5mm open ended cable that you connect from your phone/audio source to play the WAV files and calibrate the Tachometer.
The whole operation was done in 3 or so hours and it works brilliantly. So I am delighted to have a working Rev counter/Tachometer (whatever terminology suits)
Best £43 I have spent in a while, but that's also because all the Pubs are shut at the moment due to Covid19!
Hoping this is useful to someone.
Basically the existing unit was faulty and various attempts to trace the fault from the coil though to the rev counter ended with the disassembly of the tachometer and the acknowledgement that the old electronics were past their best.
So I embarked on a search for a solution and came across a company called SPIYDA who create a simple system that takes any type of input, converts it to a signal that then feeds the movement of the tachometer.
It claims to work with any rev counter and is calibrated using a rather intriguing series of WAV files which you download to your phone (or audio player)
You then play the sound waves into your Tachometer via the black box of tricks via a supplied cable and adjust the revs according to the predetermined file selected.
Not revolutionary but it works and unless your actual Tachometer movement is broken saves a good lump of cash! So here's how I did mine.
Apologies in advance for the lack of pictures as it is my first proper 'doing something' post here.
The small black box of tricks arrived Saturday, so Sunday I whipped out the Rev counter and dissembled it (I won't go into the details of this as I know there are many comprehensive examples on here)
The important wires to either re-purpose or divert are marked in the picture below.
The Black Earth wire also grounds the lights, so needs to remain.
The Green wire is a live feed for the Rev Counter only, so this will be diverted to the Black box as no Live feed is required from the box to the Rev Counter. Instead I repurposed this insulated into one of the two outputs from the black box that feed the Tachometer movement.
The Red wire with Black stripe is the output from the coil, via in my case the original electronic ignition module.
Again, this will no longer go directly to the rev counter but instead feed the black box, which in turn sends two outputs to the Rev counter.
It is worth pointing out now that when tracing this wire, in all Datsun 260z wiring diagrams this wire is Blue, which this one is also, right up to just a few inches further down the loom form this point. No idea why it changes colour to Red & Black.
Cables disconnected and casing removed.
Side on picture of old, bare electronics with casing removed.
I then got the unit on my rather crowded bench and unsoldered the Black and white wires attached to the magnetic movement of the tachometer from the circuit board underneath it.
Then, leaving the Face of the dial and needle in place I undid the two brass screws that hold the circuit board onto chassis of the unit.
Once the screws were removed I cracked the circuit board into two pieces in order to remove it without the need to remove the dial or the needle which can itself result in breakages.
Then to connect the White and Black wires to the two corresponding terminal in the SPIYDA box.
No frills here. This is a Black Box with a processor and a single tranny. Nevertheless it's fascinating to see how the jumbled collection of resistors, capacitors and other components from the original board are replaced with this......................
It does come in a Black box and measures roughly 10cm x 5 cm, so is easy to mount under the dash close to the back of the original Tachometer assembly. But ultimately you have to create your own cabling (it comes with just the 3.5mm audio cable for connecting to your phone) so can in theory mount it in the trunk if you so wish.
So..........this is where my enthusiasm to get the job done overtook my patience in documenting my progress with pictures. Suffice to say I connected the two output wires from the Tachometer movement to the two relevant terminals in the Spiyda Box of tricks. So further imagery is limited.
However you can see below my initial connections from box to Rev counter for testing.
Just the two wires from the old tachometer movement to the Spiyda box (Green and Yellow)
When I reassembled the backing and case, I actually soldered the two wires from the movement to
a) The original Green LIVE input to the Tachometer - now no longer used so a useful terminal
b) The original bullet shaped input that used to receive the signal from the coil (The old Red wire with Black stripe)
c) Finally the original Earth was connected back to the case of the Tachometer, with a split running to the Earth of the Spiyda box, as this Earth also feeds the indicator and dash lights
The Live for the Spiyda box is fed by the Original Green LIVE wire that used to run to the Tachometer.
Wiring diagram form the Spiyda for the box below for easier reference;
And finally, pictures of my Hanging Spiyda box before mounted. Exact location TBC, but it is smaller than a Gnat's rucksack so should be easy to find somewhere. Mañana.....
And last but not least, one working rev counter.......the movement of which I of course cannot post as part of the thread, but there is a still image and if you click on the link below it, you will be taken to a short burst of action on YouTube...........................
I didn't go into the depths of calibration through the downloading and playing of WAV files, but suffice to say it was straightforward as it comes with the 3.5mm open ended cable that you connect from your phone/audio source to play the WAV files and calibrate the Tachometer.
The whole operation was done in 3 or so hours and it works brilliantly. So I am delighted to have a working Rev counter/Tachometer (whatever terminology suits)
Best £43 I have spent in a while, but that's also because all the Pubs are shut at the moment due to Covid19!
Hoping this is useful to someone.
Last edited:
