[h00dedclaw]

tnx a lot

 

[KetilParow]

Hi Mr T.

Mu tacho- and speedo- meter were both moving . However, I would never get past 1500 RPM and 40 kmph. the odometer seemed to work correctly though (a bit strange that...).

I noticed there were PCBs with good old discrete components on them (a couple of transistors, resistors and capacitors) behind both the speedo and tacho. I am guessing that some of the components on these are causing these problems . electrolytic capacitors, for example, do not live forever. They will dry out over a period of time, and their characteristics will eventually change dramatically (that's why you often get noise / hum / malfunction i old radios and TVs). So if the adjustment hadn't worked for me, my next attempt would have been to change the electrolytics, and then all the other capacitors.

regards,
Ketil

 

[KetilParow]

Hi msiert.

You are probably right on this, as I have noticed that after the adjustments I made, the speedometer seems to be correct in the range from 0-60km/h, but my perception of speed tells me it shows too little above the 60 km/h mark.

However, I did not have a GPS or other speed measurement devices available when I did the first attempt, so I can't be 100% certain that this is the case, and in case, how severe this is.

this does not mean that it's impossible to get it right though. The devices may be logarithmic in their design, but you'd have to know the exact specifications of the adjuster circuit to come to that conclusion. So my guess is that you'll be able to adjust it so that both the speedo and tacho will be "accurate enough".

Regards,
Ketil

 

[John M]

Hey guys......you will find that once you set the rpm at idle to around 900 or so for an S4, the tach will be very close if not a little high. The easy way to calibrate it is at idle with a timing light that includes tach read out.....or a multimeter that includes tach read out. But if yours, like my speedo, is fairly accurate and GPS confirmed, you can set the tach at 900 @ idle and then go for a road test noting 22.14 mph per 1000 rpm in 5th gear. So....>

89 mph @ 4000
80 mph @ 3600
77 mph @ 3500
66 mph @ 3000
60 mph @ 2700
55 mph @ 2500
44 mph @ 2000
40 mph @ 1800

If calibration is the only issue, then once calibrated, the tach will work thoughout the scale. If you still have issues after calibration, its time to consider a new head unit or sending the unit to someone like Palo Alto for rebuild. Now sourcing a new head unit for a US tach will probably be quite difficult due to the air bag light through the face. The other issue is you are likely to have to buy an entire new cluster....again if you can find one.

Best Regards,
John M

 

[AlfaRormeoKY]

WOW great pics and information. How do I save it. I have a 1991 Alfa with similar situation. Will need to have this taken care of. How long does this take (for someone with experience) just curious. Diane

 

[John M]

Hey Diane:

We haven't met yet. And just to let you know we are meeting at Olive Garden in Lexington this Wednesday...aka tomorrow....at 6:45. So be there or be square.

Takes anywhere from 30 min - 1 hour to tinker with that tach/speedo depending how well its coming apart and going back together. Might be a project for a tech session. Now see if you had came last time....I could have fixed that already! I'll look forward to meeting you and seeing your ride.

Best Regards,
John M

 

[iffy215]

Hi John M and everyone,

I'm new to this forum but have owned my Alfa 93 spider for 12 years (original owner). Love my car and I finally have time again to give it the attention it needs. I had the speedo/head cluster replaced by the dealership years ago because it was reading slow (tach and odo were fine). I don't want to go that route again and zero the odometer again, but it looks like it's happening again. Thanks for the post with the detailed info. I will try it this coming weekend.

Just wanted to double check before I got into it...your method is what I should use if my speedo is reading about 10-12 mph slower than it should. About a few weeks ago, it was reading hardly anything, but now it's back to "normal" reading 10-12 mph slow. Is there anything else I should look at before opening it all up?

Any help would be great.
Thank,
Iffy

 

[John M]

Hey Iffy:

Welcome to the alfabb. You might have a head unit that is failing. I have not had one go to zero. They have always read...but just low. This is where the calibration screw comes into play. Reading zero could be the result of a broken solder connection on the back side of the pod....or could be the head unit has an internal short. So check those prongs well. Also verify your fuse is getting a good connection. No power...no operation.

Best Regards,
John M

 

[Duke58]

John M,

My 1986 speedometer looks very similar in all respects, except it has four prongs in back. Do you or anyone on the BB know if all four prongs are actually used? I suspect one is not because one of the solder points does not connect to anything that I can determine.

Thanks,

Duke

 

[John M]

Hey Duke:

My 92 only uses 3 prongs. And only three solder points on the ribbon cable. I suspect the 4th was there for support or alignment. Mine has a place in the plastic housing for four prongs...but only the 1st, 2nd, and 4th prongs are actually used. I suspect that the prongs are (not in order) ground, power, and signal.

Best Regards,
John M

 

[Duke58]

Thanks John! Those are the same pins mine uses, so I'll start troubleshooting the speedometer itself or send off to Palo Alto.

Good job on your thread.

Duke

 

[WopJob]

Lazy apeedo

I set my trim pot on my speedometer all the way counterclok wise (read 0 ohms) as if the pot wasn't there the best my speedo does is 60mph (by then Im really doing 70 or 80).

I tried without success to get the schematic for the speedo, any google search come out empty.

Do you know anything about electronics? I'm tempted to open up my pod and make a crude schematic of the thing.

I surprise that for such an "interesting" problem no one has foud a solution to it yet.

TonyG

 

[John M]

Hey Tony:

I don't know the electronic internals. But to increase your indicated speed...you need to turn the screw clockwise....not counter-clockwise. Only people I know of who truely know the head units is Palo Alto. Of course they charge a bundle to make it right....but appearantly they work afterwards.

Best Regards,
John M

 

[ziko]

Great post John,
It was the trigger for me to do the same job on my 1988 spider .
Your dials are made by Veglia and mine are from Jaeger (Europe version?)
The cluster is the same but the tacho has different connection - no pins.

Also repair the odometer , was necessity to replace the motor\gear (broken tooths)

Best Regards
Z.Shnaider

other pics of my spider, here

 

[Davey]

Great post John,
It was the trigger for me to do the same job on my 1988 spider .
Your dials are made by Veglia and mine are from Jaeger (Europe version?)
The cluster is the same but the tacho has different connection - no pins.

Also repair the odometer , was necessity to replace the motor\gear (broken tooths)

Best Regards
Z.Shnaider

other pics of my spider, here

I have a speedo / tack working but odometer is dead. I have just taken the motor\gear out. It looks fine - before putting it back in and trying is there any point in trying to power the motor to check it. There are 3 wires 2 green and 1 red. What voltage/current should i Use to drive it. The wires look very thin.

Regards.
Dave.

 

[Joe Papa Sr]

John,
Great info. Question: I have an 87 spider vel, and suspect speedo is off.
1) Assuming My setup can be adjusted like yours, how do you verify speedometer function and accuracyonce you adjust? How did you verify?
2) What have you learned in general about the accuracy about these Jaegers?
Thanks,
Joe Papa Sr

 

[Joe Papa Sr]

John,
Great info from your project! But one query: How did you verify the final correct speed on your instrument? Also, i have a 87 spider vel, and suspect my speedo is off. Is this likely given the history of jaeger instruments (which I am not neccessarily knowledgeable on)?
Thanks,
Joe Papa Sr

 

[Gubi]

Many of them are off, yes, due to the components aging.

I verified mine pre- and post-adjustment using a handheld GPS. If you have one or can borrow one that's a reasonably accurate way to do it.

 

[MrT]

I have a speedo / tack working but odometer is dead. I have just taken the motor\gear out. It looks fine - before putting it back in and trying is there any point in trying to power the motor to check it. There are 3 wires 2 green and 1 red. What voltage/current should i Use to drive it.

When I sent my '86 Graduate speed off to a US shop to have it repaired, they said the odometer motor was bad and _just_ _happened_ to have exactly _one_ more on the shelf. So it's in my speedo and working just fine. But they must know how to test them. They are in North Carolina, USA. Nichols Speedometer & Instrument Co. - Greensboro, NC

They have email access, but I hesitate to post it here. Well, it came from the web anyway, so it _must_ be OK. What I found was jcnichols at speedchk dot com, but cannot guarantee this. They might or might not take time to answer you on how to test. They sent me the non-functional motor, because I asked them. I planned to ID the problem and fix it so I'd have a working odometer motor in case I needed it. I haven't done so yet. I'll be interested in the drive specs, too.

 

[John M]

Either as Tom said with GPS....I have an AVIC-n1 navi in my 92.....or another easy way is to calibrate the tach with a DVM w/ tach feature to insure its accuracy. Then do the calibration based off rpm and gear selected.....providing you have the original profile tires on board.

Best Regards,
John M