Serial comm testing - cable ok, jibberish on screen

[Spittybug]

Prior to installing the new Max232 I checked all voltages and connectivity per the trouble shooting manual. Nothing other than what is should be. The new cable from DIY (all drivers installed per procedure) is configured as COM 6 and passes the pin 2-3 loopback test with hyperterminal just fine.

I put the Max232 into the socket that I had previously soldered onto the board, jumpered 12 and 13 together (right in front of R44) and then connected the stimulator. NOTHING on hyperterminal. NO jibberish, but also no echo. Occasionally I will get the cursor to move 1 space upon the first touch of a key, or 1 house shaped character. I have baud set at 115200, data bits 8, stop bits 1, flow control none and parity none. I also tried the jumpering right at the underside of the Max232, pins 11&12 to rule out a processor socket issue. Nope. If I turn echo on I do see the keys I type, but only 1 not 2 of each.

I've wiggled the serial connector to make sure there is no loose connection. No change. I checked continuity between each input hole on the DB9 and its connection on the PCB andthe Max232 socket. I performed the voltage and continuity checks per the trouble shooting guide. All are as they should be per step 3. I have ensured that all components are in place per the instructions, including any polarity. I know how to solder boards and components, so I am very confident in the integrity of the connections. Whole thing has been de fluxed using acetone and toothbrush.

I'm at a total loss. Other than the Max232 and the mechanical connections to DB9, the only other components in this loop are the 4 (.1microfarad) capacitors, C26, C27, C28, C29, right? I know the voltage circuit is fine, so that is ruled out. Chances of 2 bad Max232s is slim, how about something with the capacitors?????? I've double checked their connections - all solid, clean and pass any wiggle test. Hold on, let me do a board check using the diagram in section 3............

VOILA!!!!!!!!!! I'm not insane! Capacitor C28 has continuity on one leg to MAX232 pin #4, but the other leg (or hole either) has no continuity with MAX232 pin #5 as it should!!! There's a bad connection in the PCB!!!!!!!! Ok..I just jumpered it and it works!!! I HATE THESE KINDS OF PROBLEMS, BUT I LOVE SOLVING THEM! Moving on now..... guess it wasn't a bad Max232 after all. Oh well, there goes $7.

[Spittybug]

Matt, I'm all assembled and everything would appear to be ok. I have megatune up and running and have real time data from all stim inputs (once I remembered to jumper the one diode). Working on the wiring now. Took a couple hours out today to rip off the old manifold and mechanical FI stuff from the Delorean. One question came to mind as I was doing this; I have a vacuum advance for the dizzy. Upstream from it is a solenoid that gets vacuum to it if a temperature switch is greater than 104 degrees, no problem there. The solenoid only passes the vacuum through if an idle microswitch is open (ie, non-idle situation).

Is there a means to replicate this function using the MSII board? Essentially I need to energize the solenoid at idle, disable it otherwise. Can you steer me in the right direction?

Thanks,
Owen.

[Matt Cramer]

See the spare outputs page:

http://www.megamanual.com/ms2/spare.htm

You can build a relay control circuit to turn on below X RPM and above Y degrees of coolant temperature easily enough.

[Spittybug]

I think what I may just do is fast forward to my ultimate state and just use the distributor's VR output and have MSII do all the work. Yeah, getting it lined out may be a few more variables to juggle, but if I understand correctly, just by changing tables related to manifold pressure and engine temperature I can replicate the vacuum advance that this solenoid does mechanically. The centrifugual advance is purely a function of engine speed, so that is another table, right? At that point, I can also eliminate the magical "ECU" boxes in the Delorean and just by adding an extra wire or two, remove the spaghetti harness from the car. There goes another eyesore and couple more pounds!

Any words of warning/benefit on having MSII manage the ignition timing too? I know I have a juper to go change somewhere and a couple of things to double check......