jennings j400 logic board

[Rpowell18]

i am looking for a place to repair a logic board for a jennings j400 ..the board is in good shape but the copper contacts are worn..there is no acid damage on the board....i have seen places all over the internet, but have been little leary about them..any ideas...thanks

[ramegoom]

I have repaired many of those fingers, and the usual way to do it is to clean the fingers down to the copper, then coat with solder - then finally use solder wick to smooth the traces out.

The downside is, the original fingers are gold plated where the solder coated fix will contact the edge connector gold plated terminals. Eventually the dissimilar metals will cause corrosion.

The good news is, it'll take years to happen, because one of the two metals is mostly tin, the other is gold.

John

[Rpowell18]

i got the j400 board repaired and it display 190 when i turn it on after i reinsert the board..i was reading on a forum about pulling the board and turning the power on then reincertinting the board..it has a new battery installed..i was told to hold the coin switch until it tilts than push the black button on the front of the board..190 still appears ..am i missing a step somewhere ...thanks

[ramegoom]

I would keep trying by turning off the power, then turn it back on, hold the reset, hold the coin switch down, turn off then on. Possibly your power supply is in question - those have large capacitors that tend to drift badly.

Those TTL boards are very temperamental and there are so many circuits that fall back on reset checks. Early designs were modified heavily (look at all the rewiring on the boards) so there are no hard-fast rules for them. I imagine they're very difficult to repair because of the modifications.

John

[Rpowell18]

Ok I will give it a try ..thanks