Paging zaza

So....there is a small ground trace on the right leg of the tip102 that sometimes cooks off the board when he tip goes up. Hold the board up to a light and compare it to a couple of the other tip102s in the row.

Looks like pre driver is out too. Check and repl e q51 too

Pull the components and provide photos of both sides. Any carbon will need to be cleaned off the board (since it's conductive) but I'd like to see what it looks like first.

Sorry, late at the party , great advice is given already.

Measure D21 as well and check for proper contact to center-leg on solder-side. It is the fly-back diode to protect the transistor for voltage spikes.

Beside R89, R86 is heavy burnt too, I think U4 has also a failed output.

Lo-Power-Sol.jpg

Without components on output it will give different values than the others but try this:
Multimeter set to 'diode', red lead to a GND on this board, black lead to U4 pin 16, about 600mV ?
Or Compare with U4-15, this is same kind of output but for solenoid #14.

Only with powered machine and logic probe/ scope it will give more reliable information.
This can be done without 20 and 50 V connected.

Yes, correct.

As zaza mentioned most TTL logic has ESD protect diodes from the supply to the pin and pin to ground. This can only be tested when the chip is removed from the circuit. Use your DMM to measure the diode from pin to supply and pin to gnd, approximately 500mV to 700mv. Failures will most like be 0v or no volts. See attached image courtesy of the internet.

cypress-1_esd (resized).JPG

Before you solder anything I would get a fibre pen and some isopropyl alcohol and give the whole area a good clean to remove flux and charring. Then check all the damaged tracks for continuity.