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

all LEDs were out the first time all the transistors were removed

The second time all the transistors were removed the AE and WUE LEDs stayed lit.

Hope you can understand my confusion. :(

I'll try cleaning the board in that area again (I used flux cleaner and a toothbrush the first time through ...

OK - changed out the transistors. Let me see if I can get this right:

Removed them all and all the LEDs went out - good

Put in the transistor for the Acell Enrich (AE) - worked fine - very good

Put in the transistor for the Warm Up Enrich (WUE) - LED constantly on - bummer, but the AE still ...

Dave,

You mentioned checking the voltage at the transistors. I understand that they are essentially a switch. What voltages should I be looking for on which pins?

I'm thinking of changing the transistors - can't hurt - although I don't see anything obviously wrong. Replacing components w/o ...

Check the transistors that control the LEDs - any chance they're in backwards, damaged, stray flux, etc?

Matt,

There is nothing obvious, they are in matching the silk screen. I checked with a multi meter and there are no solder bridges. Is there any way to check if they are damaged before I pull ...

Good morning all,

Sometimes it is best to take a new run at the issue after setting it aside for a little bit.

I got to the end of the build (DIY kit, firmware code 2.891, using Jim Stim to validate). Everything tested fine until the last test of the output circuit.

The issue I would like to ...

OK - so if I measure the resistance across each of the legs of the small transistors when installed on the board I should get infinite resistance? (no needle movement on my multimeter when set to measure ohms). Just want to make sure that there are no back paths for the current to flow, thereby ...

Good morning Matt,

I examined all the transistors, and they are all installed in the correct orientation. There are no visible solder bridges. Is there any way to verify that they are good with the multimeter?

I wish I had a deeper understanding of the electronics - sometimes you are forced to get ...

I am assuming that Q6, 7 and 8 are the tansistors driving the LEDs. I am confident that they are instaled the correct way around (flat side matching the silk screen). I have visually checked that they are not shorted due to solder bridges, but my eyes are not as young as they once were. I'll double ...

Thanks for the quick response.

The MS LEDs stay on if the daughter card is removed.

I re-checked the voltage from the 19 pin FP pin to ground (Jim Stim)- it now reads +3.5V. I swear it was -5V earlier, but...

The Fidle pin to ground also reads +3.5V and drops to +3.0V as the light flickers on ...

I have been building my MS-II from the DIY autotune kit. I am using the Jim Stim to validate and test at each test point in the assembly instructions. The code version is something like 2891?

Everthing tested fine until the output circuit (final validation test). I have gone back through the steps ...