MSefi.com read only forum (Jan.15,2018)

Ok, I have ms2 v3 and im using a friends 2.21 stim he built but never used. Im testing the power supply, using a 9v battery. on pins 1, 2, 19, 20, 31, and 32 I an getting 7.5 volts on the 40 pin socket. no grounds on the socket. I have to use the ground off the battery terminal on the stim. I also tested U5, from left to right on the 3 pins i got 9.2v, 7.5v and 7.5v. Everything seems to be correct, do I need to desolder everything and order new parts and start over? this is also setup for a stepper iac motor. Im stumped. Is there anything on the stim that affects voltage or is it all the ms board?

I also ordered a few extra 5v regulators (u5) because DIYAutoTune suggested that may be the problem. Swaped it out and im having the same issue. I even tried hooking the 9v battery up to the voltage regulator by hooking the left pin to positive and testing the other pins and im getting the same exact results as above. The multi meter is correct, im getting aprox 9v on a 9v battery and aprox 1.5v on a AA battery (give or take .2v on them).

Thank you for your help.
Alex

Check for a short between the 12 volt and 5 volt plane.

just tested them, getting infenite resistance(like im not touching anything)

thanks,
Alex

Try removing the regulator and check the voltage on the 5 volt side without it - what do you see there?

ok battery is testing at 9.2v, testing from left to right where the regulator goes without the regulator:
8.9v, 1.8v-1.3v, 1.8v-1.3v (5v side, on the right)

on the middle and right side, it started at 1.8v and slowly went down to 1.3v, battery still tested at 9.2v


thanks,
Alex

Check to be sure the center leg has 0 ohms to the ground plane. If the ground is damaged, the voltage will have an offset to it.

ok, its reading at .001

Try adding a wire grounding it straight to the DB37 and see if that makes the voltage offset go away.

so put a ground wire directly to the center hole of the regulator in u5 from the db37? any particular place on the db37? with or without the regulator?

sorry just wanna be sure


thanks,
Alex

With the regulator, and any of the ground pins (1, 2, or 7 through 19).

ok, battery tested at 9.64v before and after testing. With the regulator in, ground on the center pin going the pin 1 on the db37. from left to right on the regulator:

9.26v, 7.51v, 7.48v



thanks,
Alex

Alxsmt wrote:ok, battery tested at 9.64v before and after testing. With the regulator in, ground on the center pin going the pin 1 on the db37. from left to right on the regulator:

9.26v, 7.51v, 7.48v



thanks,
Alex

Wonder if there is a short between the 5 and 12 volt rails after the reg? You could check for this by removing the poly fuse. The reg needs a load to work properly, so try a 100 ohm (or so) resistor between output and ground - this at least would prove the reg circuit. And are you sure D9 is installed the correct way round?

If you have 7.51 volts on the center pin of the voltage regulator, it's not grounded properly.

ok, I just checked all the db37 pins and I have no ground... I ran a wire directly to the battery then to the center pin of the regulator.

new readings from the regulator from left to right:
8.82v, ground, 4.97v

on the 40 pin socket:
1- 4.97v
2- ground
16- 8.84v
17- 3.31v
19- ground
20- 4.97v
31- 4.97
32- ground

battery tested 9.54v before and after.


did I somehow completly screw something?


thanks again for the help,
Alex

Alxsmt wrote:did I somehow completly screw something?


thanks again for the help,
Alex

Yes... you need to figure out why the DB37 isn't grounded properly.

trakkies - after the last test, will your test still help? and yes the d9 is installed the correct way.



I will check the stim to make sure im getting ground to the db37 on that.

im half tempted to buy another board and start over

thanks guys,
Alex

alright, tested all the db37 pins on the stim.
1- .001v
2- .002v
3
4
5
6
7- .002v
8- .002v
9- .002v
10- .003v
11- .001v
12- .001v
13- .003v
14- .003v
15- .003v
16- .003v
17- .003v
18- .003v
19- .003v
20- .003v
21- .003v
22- .001v
23
24
25
26
27
28- 9.6v
29
30
31
32
33
34
35
36
37


none of them tested work as a ground.

is that correct?

Alxsmt wrote:trakkies - after the last test, will your test still help? and yes the d9 is installed the correct way.

No need - you've proved the 5 volt reg is OK and that your problem is no ground to it.

I will check the stim to make sure im getting ground to the db37 on that.

im half tempted to buy another board and start over

thanks guys,
Alex

I'm still not clear if you've checked the grounds on the MS and stim individually. It's rather unlikely both are faulty.
I'm assuming the MS was bought ready made? If so, that is likely OK.

The stim you said was built from a kit but never tested. So the very first thing to do is examine the soldering - that's the most likely cause of the problem with something so basic as no ground. If it looks poor it would be easiest to just re-flow the lot. If you're unsure what it should look like take pics of both sides of the stim board and post them here.

Alxsmt wrote:alright, tested all the db37 pins on the stim.
1- .001v
2- .002v
3
4
5
6
7- .002v
8- .002v
9- .002v
10- .003v
11- .001v
12- .001v
13- .003v
14- .003v
15- .003v
16- .003v
17- .003v
18- .003v
19- .003v
...

none of them tested work as a ground.

is that correct?

I don't get it... the pins read zero volts, but not ground?

this is a kit im attempting to assemble.

I tested all the pins on the ms for ground with the stim attached but without the extra ground wire going to the regulator(tested pins on the bottom of the board). Then I tested the pins on just the stim, the results I just posted.

correct, none of them worked as a ground.. the soldering looks good on the stim, maybe a few spots could use a little more solder but they deffenetly make a connection. I will resolder them and see where that gets me.


thanks guys,
Alex