I am in the process of building a MS for the first time. I built my jimstim and plugged it in to perform an op-test of the pcb power circuit. I receive ALL voltages where they need to be, but I am getting 5V on pins 19 and 2 of U1 (CPU). According to sheet 1 of the schematic (Megasquirt-CPU,Rev 2.991) both should be grounded directly with only a cap (C1) connected to power. I checked the cap and it tests fine. Also pin 32 should be directly grounded per the drawing but no dice. There is no direct short to ground that I can find from the power circuit.
Is there a change to this drawing or did I screw up my pcb build?
MS pcb 3.0 voltage on U1 pins 19,2?
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Read the manual to see if your question is answered there before posting. Many users will not reply if the answer is already available in the manual.
If your question is about troubleshooting, configuration, or tuning, you MUST include your processor type (MS-I or MS-II) and code version in your post. If your question is about PCB assembly or modifications, you must also include the main board version number (1.01, 2.2 or 3.0).
If you have questions about MS1/Extra or MS2/Extra code configuration or tuning, please post them at www.msextra.com Such questions posted here will be moved to: a temporary MSextra sub-forum, where they will be removed after 7 days
The full forum rules are here: Forum Rules, be sure to read them all regularly.
Re: MS pcb 3.0 voltage on U1 pins 19,2?
My guess is you didn't let the solder flow properly when installing the 32 pin socket. Or were using too thick a solder so not enough flux. Are other joints like resistors showing a good flow on both sides of the board? And are you using lead solder?
Dave P, London UK.
Rover V-8
MSII V3
EDIS
Tech Edge Wideband
Rover V-8
MSII V3
EDIS
Tech Edge Wideband
Re: MS pcb 3.0 voltage on U1 pins 19,2?
I am using .32 lead free solder. I am a veteran Navy certified electrician and have been soldering for a long time. My terminals look like the pictures in the Navy manual. I have continuity tested alot of points on the pcb with my DMM and have .03 ohms restistance. I will however try and reflow the points on U1 when I get home.
I'm pretty sure that poor solder points aren't going to generate 5V though.
I'm pretty sure that poor solder points aren't going to generate 5V though.
Re: MS pcb 3.0 voltage on U1 pins 19,2?
I'm surprised you're using lead free if ex-navy - it's my understanding the military won't allow it anywhere.
I based my comment on the ground connections being IIRC on an inner layer of the PCB, so most likely not making a connection due to a soldering problem. If the ground plane is at 5 volts the same applies - but elsewhere. Where were you picking up your DVM ground?
I based my comment on the ground connections being IIRC on an inner layer of the PCB, so most likely not making a connection due to a soldering problem. If the ground plane is at 5 volts the same applies - but elsewhere. Where were you picking up your DVM ground?
Dave P, London UK.
Rover V-8
MSII V3
EDIS
Tech Edge Wideband
Rover V-8
MSII V3
EDIS
Tech Edge Wideband
Re: MS pcb 3.0 voltage on U1 pins 19,2?
Actually I found an ID-10t error. It helps if you ID the right pin as #1. Lower right not lower left. 
No problems.
No problems.Re: MS pcb 3.0 voltage on U1 pins 19,2?
As far as lead free solder- I am building this thing on my kitchen table and my kids like to observe and touch everything; better safe than sorry.
Thanks for the input guys!!
Thanks for the input guys!!