What is inside a Polaris Ficht EMM, computer/logic/ignition/injector driver board

[MacGyver1981]

I noticed that c27 was burnt and 28 was cracked. It didn’t idle very well but I found the fpr in the bottom of the tank. Now I have done the repair. The reason for looking was a post I read on here. I haven’t found anything else in there that stands out. But decided to change the capacitors also the dielectrics. So am I correct in thinking I should change the MOSFET ?

[HiPeRcO]

I noticed that c27 was burnt and 28 was cracked.

You mean like this? These capacitors get replaced on every EMM repaired here at Lakeside Tech.

[MacGyver1981]

Pretty close to that. The traces are still good they didn’t burn off.

[WaveChaser]

Has anybody verified what potting gel the EMM uses? Electrolube-UR5048 looks like it would work. They say it is "digoutable".

I have to say removing the potting gel and digging into the EMM was intimidating at first. I was scared I would physically break something but over a couple hours with a brush and fingers, I dug out all the gel. It actually rubs off like rubber cement. I have an IR heating table and heated the EMM. I moved this board gently side to side and lifted it gently out. It was easier than I thought.

Here is my opinion after years of fixing circuit boards and the amount of time it takes to get this apart. Shotgun all the capacitors especially tantalum and electrolytics. These EMMs are going on 20 years old and some are over. The silver can smd eletrolytics leak and damage circuit boards. As I have seen in this post, Tantalums will short without notice. I have 5 EMMs and C27 and C28 are replaced in all of them. I also agree to increase the voltage rating to 50v on them. I have a dead EMM that they shorted so bad they burned the surface of the circuit board and trace between them. So for $20 in capacitors, it is well worth it to breath new life into your Ski and eliminate weird problems.

I would also clean and replace all the heat sink compound on the CPU/Logic board. It dries out over time and will not efficiently conduct the heat to the water cooled heat sink.

C89 will cause the ski to shutoff without notice but start right back up again at least that is what mine did.

[RailGS]

Добрый день. На моей плате управления источник питания +5 В исчез на выводе 25. И как подключить плату на столе.Спасибо.

Good afternoon.
On my control board, the +5 V power supply disappeared on pin 25.

And how to connect the board on the table?
Thank you.

[RailGS]

test EMM

Good afternoon. On my control board, the +5V power supply disappeared at pin 25. And how to connect the board on the table.Thanks.

https://youtube.com/shorts/HkOg8gng924?feature=share

the problem is solved, connected the signal generator

[K447]

What are you testing for?

Can you provide more details on how the test rig is constructed?

[RailGS]

good morning

https://cloud.mail.ru/public/4MMr/BQyZoLDLH

Generator https://a.aliexpress.com/_Acy9hi
magneto generator marks signal diagram https://cloud.mail.ru/public/pVjL/uju95TdiF

[K447]

..,
magneto generator marks signal diagram
https://cloud.mail.ru/public/pVjL/uju95TdiF

The last link does not display properly for me.

[RailGS]

The last link does not display properly for me.

this is for programming the generator chip
111010101010101010101110101010101110101010101010
something like this

[RailGS]

good morning

https://cloud.mail.ru/public/4MMr/BQyZoLDLH

Generator
https://a.aliexpress.com/_Acy9hi magneto generator marks signal diagram https://cloud.mail.ru/public/pVjL/uju95TdiF

Initially, we set the positions of the TPS sensor, while the LED should go out. Having measured the readings on pin 3, it should correspond to 0.15-0.25 V. Next, we connect a signal generator For diagnostics on the operability of EMM. It is necessary to connect the oscilloscope to the pin of the injector 2 or 12 . When the TPS sensor is rotated, the fuel supply readings on the oscillogram should change.

[K447]

Initially, we set the positions of the TPS sensor, while the LED should go out.

Having measured the readings on pin 3, it should correspond to 0.15-0.25 V. -

My experience has been that the 'idle position' TPS output signal is approximately 0.350 volts. This varies between watercraft, sometimes as much as 0.450 volts, sometimes 0.300 volts

The fuel injector drive pulse signal is derived from a combination of the TPS signal voltage and the CPS magnetic trigger signal (RPM pulse rate).

[adamvu]

Hmmmm . . . can you please tell me what you used to remove the aliphatic polyurethane potting compound? Obviously you start with picking out the bigger chunks, but it looks like you used some sort of board wash.

i soaked the board in lacquer thinner for couple day. and blow off with compress air. capacitor cover some of them are fall apart but not sure will damaged any other components

[K447]

i soaked the board in lacquer thinner for couple day. and blow off with compress air.

capacitor cover some of them are fall apart but not sure will damaged any other components

Welcome.

Are you saying the lacquer thinner damaged some of the capacitors on the EMM circuit board?

And you do not know whether any of the other electronic components were damaged by soaking in lacquer thinner?