TeamSwift

Ok - good pics. I can see that this was probably like a '97 or '96 instrument cluster. That's my guess. You are right, it was from a car with a distributor. R2 and R5 both need to be changed. When you put the pot in I assume you took R5 out of the circuit. But notice that R2 is also significantly different when you look at it on your board. Check the value that my distributorless board has for the 4cyl. The other values on your board all look OK. The chip on the '98 up board has no connection at all to the pin that the jumper goes to. So leave it unconnected. The same with the diode - get rid of it.

Try to clean up the solder joints. Remove the diode. Remove the jumper. Leave the capacitors as is. Replace R5 and R2. You might experiment by using two pots, one for R2 that you set correctly with an ohmmeter before soldering it in. Then another pot set for R5 - before soldering it in. With the diode and jumper gone your board will have the same values as the '98 board that I posted pics of.

The numbers on our chips differ. But that doesn't mean that they are totally different. Your circuit obviously works the same as the circuit on the later model board, like the one I posted pics of. I'm going to spend a bit more time studying your new, larger pics and comparing them with photos that I took of the '98 up board that are archived on my pc. I have some shots that show the bottom of the board (just not real clear). I'll study this a little more and get back to you again.

Sorry you're having so much trouble with this. Your original problem was that you had no idea what year car your cluster came from. And now you know it was not '98 up. But it still might work. So try again, but be sure to change R2 also.

Unfortunately we know nothing at all about the internals of the chip. And we never will. If I had a datasheet on that chip I could tell you exactly what is wrong. I am hoping that there is nothing wrong with the meter movement on your tach, or that there aren't any wiring problems preventing the signal from getting to the board.

Also, I might mention that unless you are plugging all of the connectors into the cluster to test it, you may not be getting power to the board. I test them using only a few wires that go to the correct pins on the connectors. And I had a difficult time finding the right pins to get the correct power and ground. Just thought I'd mention that in case you're not plugging the entire cluster in to test it.

I can imagine that this project has been a royal pain in the butt, right?.

thanks wired. i soldered the wires into the harness just behind the speedo, and brought them out and under the dash. so I'm sure i have good connection at that point. the rest you have covered and is sounds like you were able to review the pictures i reposted to verify things. again thanks. when i get the components your sending i will replace them get the pots suggested and try again. most likely these are the issues. the chip is more that like ok and just may have came from a different supplier then your chip. manufactures sometimes can't get the amounts they need from a single chip maker. bob p.

The temperature coefficient for a 10-15 turn precision pot is minimal, especially if it's in series with a 1% metal film fixed resisitor.

Thing is here, there are comparators and one-shots inside that tach chip that require precise biasing so that they trip right between 0 volts and the peak of the input pulse so that the remainder of the frequency-to-voltage converter can output a signal somewhere near where the meter movemove will respond. R2 could be such a critical component (it needs to be 68K insteadof 33K) and R5 should be the proper value for the peak voltage of the distributorless input.

The diode could provide a bias voltage as well - one diode drop, 1.2v - that might affect the way the chip operates.

I will say it again: Clean up the connections, replace R5 and R3 with the correct values, get rid of the jumpers and the diode. If the chip on this board has anywhere near the same characteristics of the '98 up chip, the circuit will work fine as long as there are no other problems like bad meter movements or bad external wiring.

note sure if it my pc colour but when I look at your cct board components I see an R1 at 24ohms 1W where is 390 ohms come from?
this would be the main 12V DC to the board also there is a diode all it would do is prevent reverse polarity or snub reverse transients.
Now that resistor R2 looked to be a 68 ohm between pin 15 and 16 then I see different photo shows a 33K ohms.
if pin 16 is VCC then I would expect the 68 ohm or IC will not work.
This was looking at the factory tach circuit board photo dsc00619a.jpg
Please confirm your resistors.
If the distributor less output signal is much less than distributor type measure voltage the signal is probably much lower voltage.
you could probably insert a 1Kohm for R5.
Please confirm the resistor values.

this is what is get with a dvm across the resisters without cutting or desoldering one lead.


r1 = 24 ohm
r2=780
r3=91
r4=91
r5=42.4k
r6=9.93k
r7=6.38k
r8=6.38k

say wired i thought you had some of the parts extra you were going to send out to me? i have been waiting if not let me know so i can look online and get the pars i need to reconfigure this pc board to work on my car?
my address again ia 1393 quarterline rd. muskegon mi. 49442 thanks. bob p.




quote="wired"]If you have no local electronics supplier use http://www.digikey.com/

I have parts from a 4cyl board that just got shoved aside after I set it up for a 3cyl engine. They're in perfect condition. I use a professional desoldering tool to remove components, so they come out clean and undamaged.

If you'd like to PM me with a PO box or physical address I can mail them tomorrow (Monday 20th April).

I don't have a 14K resistor since the only mods I've done have been 4cyl-to-3cyl. But I can send a 12K and you can substitute a 10K pot. This would give you a bit more range for adjustment and probably not hurt anything else

The pots like the one in my pic of the finished installation are a standard radio shack item.

Maybe you could take a look at the resistors on your board and see if the colors look the same as the ones in my closeup pic of the unmodified 4cyl board. Note that some of the resistors are the same on both 4cyl and 3cyl boards. A quick check might be a good idea to find out if there might be other values that you'd need besides the ones I would send.

You might be able to get up and running a bit sooner with my old 4cyl parts, rather than wait on a digikey order.[/quote]

Ok i hate to bring up such an old thread, but can anyone tell me if this can be done with a Mk3 cluster? or would i just have to buy one tear into it to find out for myself?

if your question is, "can i re-scale a 4 cylinder mk3 tach for 3 cylinder operation (or a 3 cylinder mk3 tach for 4 cylinder operation.") the answer is yes. as a matter of fact it's easier to re-scale the older tachs.

because the 98 - 2001 4 cylinder cars used a distributorless, coil per cylinder, coil near plug ignition system the tachometer instrument was way different from the older pulse type movements. the tachs in those newer cars actually have a meter drive circuit that has a bunch of frequency to voltage conversion going on and they aren't easy to re-calibrate (which is what this thread was all about.)

considering that, if you have a working 98 -2001 4 cylinder tachometer equipped instrument cluster i'll trade you a 92 - 97 cluster of any type you need for your car.

_________________
1991 Blue Geo Metro Convertible highly modified 1.0L Turbo3 5 spd. - 1991 Red Geo Metro Convertible customized with a Twincam 5 spd.

My Turbo3 Project
My Cardomain Page -Ol' Blue
My YouTube Channel
My Photo Gallery
SAAB Sonett II

Well man trust me if i had one i would of already put it up for trade, I always keep my eyes open for 'rare' parts when i hit up the junk yard. but here lately the prices have skyrocketed and now its becoming harder to justify the cost's of picking something up.

Hell it used to be you would go into u-pull it and pick up a head for probably about $50-$75 now they want 150.

wish i had the space for a parts car.

but i'll keep my eyes open next time i head out, if i find one i'll let you know, Now I'll do some more searching around about it. do you happen to have a link saved talking about doing it?

ETA: Link to a Mk2 Cluster Adjustment

viewtopic.php?f=5&t=12108&st=0&sk=t&sd=a&start=100

and the answer to my question.
http://www.teamswift.net/viewtopic.php?p=151914#151914

(I'll keep adding links for some cross reference)

someone has built one? I have an ebay 1.o 3-cylinder 5-speed cluster with speedometer. I want to put tis in a car 00 1.3. what has been done yet? play in a post that has an automatic trans the necessary elements are clusters int. I do not see it but it might be hidden somewhere. or in any one of you will blame me if I send the circuit to make a change? thanks bob thing.

00 1.3 auto
91 vert 1.0 5SP
90 1.0 auto hatchback

unfortunately, you can't use anything except a tach from a 98-2001 4 cylinder tach.

in 98 they changed the ignition type to a direct fire electronic system that uses a coil near plug set up. the input for the tach in those uses the low voltage drive side of the coil to derive engine rpm. the older tachs want to see the inductive spike from the coil as an input (which is somewhere around 15 volts after it runs through a pie/ noise filter.)

the tach drive on the newer units is much more sophisticated and the older tach drives are not compatible.

_________________
1991 Blue Geo Metro Convertible highly modified 1.0L Turbo3 5 spd. - 1991 Red Geo Metro Convertible customized with a Twincam 5 spd.

My Turbo3 Project
My Cardomain Page -Ol' Blue
My YouTube Channel
My Photo Gallery
SAAB Sonett II

also make sure you get the performance cam from Mike for it , you will forget all about full swap

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