My Megasquirt 2 Extra v3.0 - assembly issues - noobie

[adrian3500]

from my R56 is kind of half sticking out some metal part....so i suppose it's damaged.
I got from one of my local shops something that does the same as the R56 CT94W103-ND, same 10k Ohm, same 3 legs, same screw on the head of it.
it's written on it 850-208-100R.

Should i try to install it?? or need to stick to the original R56??

[adrian3500]

from my R56 is kind of half sticking out some metal part....so i suppose it's damaged.
I got from one of my local shops something that does the same as the R56 CT94W103-ND, same 10k Ohm, same 3 legs, same screw on the head of it.
it's written on it 850-208 vrn.

Should i try to install it?? or need to stick to the original R56??

[billr]

Those little pots are pretty generic, so the sub will probably be fine. Pay attention to the little picture on it that shows which pins are CW, wiper, and CCW. Make sure those can be installed in the same positions as the old one. Those pots will vary in the number of turns end-to-end, so be aware the sub may need a different number of turns than specified in the manual. Full CW or CCW will be easy if it "clicks", otherwise turn it 20 or more to be sure.

[adrian3500]

tried with the new pot...

at pin 3 of U7 i got 4.48 - 4.50v either way i am turning the pot. I have turned it all around....
at pin 2 of U7 i got 4.73v
at pin 1 of U7 i got 3.45v

i guess i should try finding one original pot
or maybe this new pot is faulty also?
i have installed it same way the original pot was installed, with pin 1 pointing to the middle of the board....


P.S: I could send my megasquirt to someone in Europe, assuming he can fix it....

[billr]

R56 doesn't directly change any voltages at U7. Take some voltage measurements at the base and emitter of Q23.

[adrian3500]

R56 doesn't directly change any voltages at U7. Take some voltage measurements at the base and emitter of Q23.

input 5v
measured between the 3 pins of Q23, from left to right:
1-2 0v
1-3 4.53v
2-3 0v

measured from ground to the 3 pins of Q23:
pin 1 - 0v
pin 2 - 3.50v
pin 3 - 4.56v

measured from gorund to the 3 pins of Q23, 6 turns clowise turn R56:
pin 1 - ov
pin 2 - 3.20v
pin 3 - 4.64v

[billr]

Those readings aren't making sense to me. If 1-2 = 0, and 2-3 = 0, then 1-3 should = 0, but you are reporting about 5V. Regardless, does the Q23 "pin 2" not change from near-zero to near-5V as the pot is turned from end-to-end? If so, take measurements at the three pot pins. Those should be (relative to ground) 0V, 5V, and one that "sweeps" 0-5V as the pot is adjusted. I don't have a board handy in front of me, so "left-to-right" doesn't help me identify the pins; but I'm pretty sure the one you call "1" is the collector, "2" is the base, and "3" is the emitter. Check the P/N on Q23, and check that it is installed in correct orientation (or post a picture).

[adrian3500]

measured from ground to the 3 pins of the R56 pot, with 5 volts input:
pin 1 cw - 0 v
pin 2 - changes from 0v to 5v while adjusting the pot clockwise/anti-clockwise
pin 3 - 4.80v

measured with 0v input, same results.

Q22, Q23 are installed as in the assembly guide, with the rounded face away from the CPU (rounded face pointing to the shorter side of the board, to D24)
(Install and solder Q22 and Q23 {ZTX553-ND}. These are located beside D24 (which you just installed), closer to the heat sink. The side of Q22 & Q23 with the rounded edges (i.e., the shorter of the two flat sides) is referred to as the 'rounded side', and it goes away from the CPU for both Q22 and Q23. If you imagined the side that had rounded corners was completely round, then it would match the PCB silkscreen).

I think it is visible in the link with the photos i provided on the first page of my topic.

[billr]

Confirm: voltage at pin 2 of pot R56 does vary, but voltage at pin 2 of Q23 does not? That is a direct connection, so either the board trace is damaged or (at least) one of the two solder joints is bad.

Yes, that stuff is visible in the pictures posted; I went back and peeked again. What also shows is some messy soldering in that area, and other holes where solder didn't flow through to the component-side. If the "mess" is just flux residue, clean that off and post another picture. You could also just scab-on a short jumper wire from the pot to Q23, it is a very short distance!

[adrian3500]

Confirm: voltage at pin 2 of pot R56 does vary, but voltage at pin 2 of Q23 does not? That is a direct connection, so either the board trace is damaged or (at least) one of the two solder joints is bad.

yes, i confirm it.

should i try to jumper pin 2 of R56 to pin 2 of Q23?
i jumpered the 2 pins, and now Q23 seems to work ok. Turned R56 to get around 2volts (1.71v actually) at pin 3 of U7, and now at Q23 i got
pin 1 voltage - 0
pin 2 voltage - 1.30
pin 3 voltage - 1.80

Following the test from here: https://www.diyautotune.com/support/tec ... -tests-vr/
now that at pin 3 of U7 i got 1.71v
pin 2 of U7 i got 4.88v
but at pin 1 i got only 0.13v. (it says it should be 3.5-5v)

grounding the input voltage, the input voltage is 0.20v, and at U7 i got:
pin 1 - 3.67v (should be 0-1v as it says...)
pin 2 - 1.11v
pin 3 - 2.03v


U7 faulty?!
or some setting in TunerStudio does interfere with this?

[billr]

I'm going to have to study some, because right now I'm thinking that DIY article has the U7A operation backwards. I think they are describing it as "non-inverting" from the VRin to the U7A output (U7 pin 1). I am seeing it as "inverting"... A big difference there, and I don't want to lead you astray!

[adrian3500]

supposing that it's described backwards, then i should get some activity on composite logger/trigger logger?
Still, no activity, empty read, no data received from controller.
(i tried going high/going low).

[adrian3500]

should i try to jumper TSel - VRoutINV, instead of TSel - VRout? I've read that if i want the signal to be inverted, i should do this.

[billr]

Don't let me lead you into the weeds by bringing up the word "inverted". Having the signal (or settings) inverted wouldn't prevent some kind of signal being logged in the tooth-logger. However, if I am not understanding the circuit operation correctly, then any trouble-shooting steps or measurements I advise may be completely bogus.

I know you are eager to make progress, but waiting for others to chime in (or for me to determine if I am making a mistake) will be in your best interests!

[DaveEFI]

If you've had to jumper a track on the PCB, I'd look very carefully at the soldering on all the components in this circuit. Use a strong light and magnifying glass if needed.
Make sure the solder has flowed to the other side of the board in every case. Pay special attention to the transistors. I don't like these mounted flush to the PCB as you can't then see solder bridges etc on that side.

[billr]

Dave, did you peek at the pictures the OP posted? I already advised that solder has not filled all holes, and that the PCB is pretty messy in the area of that trace; that it should be cleaned-up and a new picture posted. Maybe it is just flux, but maybe damage to the PCB. Right now, it seems there is no connection from the R56 wiper to Q23 base, so it either has to be damage or a poor solder joint there.

I (and the OP, I'm sure) would appreciate your continued help here. We got bogged-down when the DIYautotune trouble-shooting steps didn't make sense to me.

[DaveEFI]

Dave, did you peek at the pictures the OP posted? I already advised that solder has not filled all holes, and that the PCB is pretty messy in the area of that trace; that it should be cleaned-up and a new picture posted. Maybe it is just flux, but maybe damage to the PCB. Right now, it seems there is no connection from the R56 wiper to Q23 base, so it either has to be damage or a poor solder joint there.

I (and the OP, I'm sure) would appreciate your continued help here. We got bogged-down when the DIYautotune trouble-shooting steps didn't make sense to me.

I did see the pics, but weren't close enough here to give much of a clue.

I really just mentioned it because quite a few of the home made boards I've repaired have had soldering faults. And one or two pro built ones too.

It costs nothing to do a careful examination by eye first - before replacing any components.

I've not really looked at the guides for fault find this bit as I'd just plug up a stim and check with a scope.

[adrian3500]

soldering&cleaning up, checking for good soldering, is far beyound my knowledge....i don't want to make things worse
I'm not so sure that i didn't damage the trace from R56 to Q23 when removing/installing the new R56. Or maybe just bad soldering, because those legs of R56 were pretty small in lenght.

at this moment, i would be glad to sent it to someone to fix it in Europe, whatever the costs will be....

(i talked to someone here in Romania, but he said he never used the VR sensor conection for a hall sensor. He always used the XG1-XG2, OptoIN-TachSelect, TSel - OptoOut).
I have tried those conectios at the beginning, and still did not work. Reading about this, found a post here on the forum, where people say it's better to use the vr sensor conection for a hall sensor with pullup.

[billr]

Cleaning is fairly simple and easy. Just use a soft brush and lacquer-thinner, or alcohol (either ethanol or propanol); then follow with a hot-water rinse. I encourage you to do that, at least, as then we can get a good look and may be able to help you fix this without having to send it out.

I don't know how much trouble or expense it is for you to send something to the UK, but there are several folks there that could take care of this, for sure.

[adrian3500]

Seems that i will send it tomorrow to DaveEFI, if he agrees.
Tiny little soldering drive me crazy.... and i would preffer to be in hands of someone who knows more than me...