[Valeriy Gromov]

Yes, this is it. I’ve got Jaeger amplifier box under rear seat, a the sender is almost blank. Just a coil.

Like this.

 

[alfaparticle]

Can you identify the tracks on the board that connect to the coil at the end of the board? If so measure the resistance. It should be a few ohms. Then solder the two insulated wires of the cable to these tracks. The braided shield does not have to be connected to anything.

 

[Valeriy Gromov]

The printed circuit board in the 4th picture looks like an amplifier. Are there components on the other side?

No, just a coil. I think I’ll clean everything, change the wire and fill with epoxy from bottom to top.

 

[alfaparticle]

In late 85 Alfa introduced (in the US) the new shaped sender with a coil at the end and an electronic circuit on a circuit board like the one in post #78. They were unreliable and for Milanos sold in the US the electronics were removed from the sender and relocated to the Jaeger "amplifier" box. I have not opened up one of these senders but thanks to Valery Gromov we now know that they retained the circuit board but installed no components and just wired the connector cable to points on the circuit board that connect to the coil.
To answer Valery's question, a new cable can be soldered to the same place leaving the braid not connected to anything. That is the repair for a sender with the cable cut off at the sender. The coil should measure about 4 ohms if it is undamaged.

 

[Valeriy Gromov]

Opened the donor sender (1.8 ie), as I needed good sender's body. Mine was cracked.
"Opening" the sender for the second time was much more faster and easier. Although its took pretty much time to take away epoxy on the top of the sender.
That's how it can be done:
1. Drill the epoxy all around the top of sender for the depth of about 3-5 mm, till the sender cap under the epoxy could be seen.
2. Take a flat screewdriver and scratch the epoxy between the sender's cap and its body completely. See the picture. This step took almost half an hour for me, as I tried be careful as much as possible.
3. Move the sender cap by screewdriver carefully in different directions in order to push it from its seat.
4. Pull it and have a beer. It's done!

 

[alfaparticle]

Nice work. Do you plan to bypass the electronics in the sender and use it with an amplifier?

 

[Valeriy Gromov]

Nice work. Do you plan to bypass the electronics in the sender and use it with an amplifier?

Well, I plan to use my blank sender with donor body, as the coil is still alive, but....
That’s good idea to bypass electronics in “coil-only” mode!
Thanks!

 

[Valeriy Gromov]

Can you identify the tracks on the board that connect to the coil at the end of the board? If so measure the resistance. It should be a few ohms. Then solder the two insulated wires of the cable to these tracks. The braided shield does not have to be connected to anything.

Done.

 

[martingtv]

Did anyone use the model sgi-100bt? The sgi-5c worked before. The sgi-100bt doesn’t see an input signal.

I measured the input signal on the terminal.

 

[martingtv]

11k resistor between input and gnd did the trick

 

[alfaparticle]

As described in post # 55.

 

[AlfaBBuser]

Hey, great thread hope this is the right place to ask if anyone can help out with a related problem I'm having. My speedo does not work. Specifically it was reading about 30% low, then it stopped working, then it started again but about 50% low, etc. Now it's dead again. All over the course of about 2 years.

But, the sending unit, the wiring in the car, and the speedo all work together when tested when a drill is spun near the sending unit. (Sending unit removed from tranny for test) The Hall sensor in the sending unit picks it up and it moves the speedo needle and increments the odo. So it seems the whole system works end to end (also tested with two different speedos and two sending units - all fine under test) But when the sending unit is put back into the transmission, nothing.

So I am thinking there is a problem with the toothed gear inside the transmission that is supposed to pass close by the sending unit to generate the pulses, it is perhaps stuck or misaligned. Any thoughts or experience with this? Does anyone know what the P/N is for this toothed gear on a 3.0 litre 24V 75? I checked on Eper but it was not obvious to me.

 

[alfaparticle]

I believe that the sensor counts the splines on a shaft. The sensors that I am familiar with are inductive - not Hall. If you can borrow an LCR meter and set it to mH you should see a small change as the splines pass by. If you can borrow an oscilloscope you should see the sine wave that I posted on one of the sensor wires and you should see a frequency shift as the splines move by.( with the ignition turned on.)

 

[AlfaBBuser]

Thank you Ed. Unfortunately I don't have an LCR meter or a scope handy, but I am pretty sure something is going wrong mechanically inside the transmission as the rest of the system from sending unit to speedo seems to work. But if the sending unit is counting splines on a rotating shaft that would suggest some kind of misalignment as it seems unlikely a shaft in the transmission is not rotating. I guess that makes sense as there was no obvious 'trigger' I could see in the parts diagram. It seems the transmission will probably have to come apart to get this figured out. I was just hoping to hear from someone with a similar experience.

(I thought it was a Hall sensor, you may be right it could well be inductive)

Dan

 

[alfaparticle]

Could it be a wiring problem in the car? Could you hook a speedometer straight to the amplifier box under the seat, get the rear wheels off the ground and run the car in 5th gear?
The 3 pin connector carries 12V and GND to the amplifier and outputs a pulse train. Be careful to avoid shorting the output to ground when power is connected.

 

[alfaparticle]

I recently found a new failure mode. The 3.3 microfarad capacitor. I am almost sure that it had caused intermittent problems before it died completely.

 

[alfaparticle]

I can no longer offer the free testing & repair service but I can still provide troubleshooting advice.

 

[pantera928]

Do the speedometers in the S4 spiders work the same way?

 

[11636]

It Works!

Everything is installed in my GTV6 and it works. I have attached a schematic. It is more relevant to GTV6 so I will post a link to it from the GTV6 forum.

Dear Ed,
just to bring back this old thread form the dead:
I have connected everything according to your diagram (Dakota SGI-5C box: switches 1ON, 2/3/4OFF, black Jaeger box, Milano 3 wire sensor and GTV6 Veglia speedometer) and i have measured the speedometer reading with the GPS. Up to 100km/h is nearly spot-on but after that it starts fall behind i guess 10-15 km/h.
Problem is, that when i try to calibrate the speedo using the UP and DOWN buttons, nothing seems to happen. I do know that the Dakota box works, as the green light is ON and when i did change the position of the 1st switch to OFF, i got different speedo readings (far off this time).
Please note that in the past i did use this same box on my former transmission (75 Twin Spark, no Jaeger black box, old sender with metal probe, same Speedo) with no problems at all: the needle then moved up and down, as long as you pressed the buttons.
Any ideas, what might happen now?
Thanks in advance for providing the community with so much amount of highly useful knowledge.
Kind regards,
X