W1UJ SteppIR 4el 'Original Controller' Repair 2011
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My SteppIR controller failed due to 2 pins shorting our with a 'cat whisker' only when the
DB25 pin was plugged in. When unplugged from the controller, it would be appropriately open.
The Driven element was shorting to the second director, which is also why the 3el controller worked perfectly
I found this, by narrowing it down after replacing 6 chips & 2 tower climbs...
I damaged the board's traces with this much attention to it. The traces were repaired with #24 magnet wire.
I share this to hopefully help save you!
Initial troubleshooting of the chips, other than bad SWR and not hearing motors turn
is putting an Ohm-Meter across Pins 1&2, then pins 5&21. Normal, working chips have
8 Meg Ohm resistance on the motor output pins.
And the bad chips... The first picture is the driven element driver and the 2nd director.
The driver board is removed from the display/front board of the controller and faulty chips marked
The first chip removed.
My initial approach for the chip was cutting each leg with diagonal cutters and removing the leftovers
This seemed to be rough on the delicate surface mount traces.
My second approach was to use the fine tipped soldering iron to 'pick' each pin off.
Like technique #1, was dangerous to the delicate traces
My final technique, which I recommend, is using an 'Exacto' type knife to cut the top
of the pins alongside the chip clean through on one side, score the other side with the knife
then just fold the pins until they snap, then just use your fine-tipped iron to sweep away the debris
Mouser order arrived! 6 chips shipped ~$20
One chip changed out
Both chips changed out
Like a champ!