The board was inside an old hydraulic conveyor machine (produced in the 80's or 90's)

Unidentified Object

EDIT: after asking for a schematic: This board tests limit switches and light some LEDs. All switches inputs have 3.3 kOhm pull ups also these inputs are RC filtered and straight into this chip (at net between cap and resistor). The LEDs are directly driven by this chip, each with 150 Ohm resistor in series. Other than that everything is weird. The pull-up supply voltage rail is not connected to this chip at any pin. ground is connected to pins 20-26-27-28. I may do a neat schematic and further tests but I don't know how will that help identifying the chip.

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    \$\begingroup\$ A bit more context like a partial reverse engineered schematic could be helpful. As it is I would guess its some kind of motor controller \$\endgroup\$ – PlasmaHH Jul 19 '17 at 13:58
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    \$\begingroup\$ maybe someone from the old folks here could identify the logo , and then you would know if it is a logic IC , microcontroller or ASIC !! \$\endgroup\$ – ElectronS Jul 19 '17 at 14:47
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    \$\begingroup\$ Are the leds earthed through the chip? \$\endgroup\$ – Solar Mike Jul 19 '17 at 15:00
  • \$\begingroup\$ @SolarMike I was like "funny question!" but then... no its not the same ground as the chip's ground. the chip ground is common with the external ground. The LEDs share a same common but not chips ground! what does that mean and how on earth did you know!? \$\endgroup\$ – fhlb Jul 19 '17 at 16:25
  • \$\begingroup\$ @SolarMike the LEDs common is connected to the output of an LM317K regulator. aslo connected through an RC filter to pin 23 of the chip \$\endgroup\$ – fhlb Jul 19 '17 at 16:54

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