IKA stir plate RET Basic, Won't stir. Water spill under motor, destroyed SMT resistors and traces.
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IKA partslist gives the part nos. for this modelThe main PCB is: IKA part no. 3185001, price in 2018 is $305.00. The motor is: IKA part no. 2869900 (in 2018 price $312.00) (motor wo/magnet.) It's an EBM PAPST 24V DC fan motor, (16-28V-) Ebmpapst part no. M1G055-AI01-01, which I don't find in their PDF catalog.
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The four pins for the motor electronics are, top view from left to right:
- +24VDC (more like 33V in the stirplate)
- Tachometer out, Hall chip, TTL O.C. output
- V(inp), 0-5VDC gives analog 0-1000RPM.
- Gnd/common
The motor speed-ctrl electronics is digital, with a hcf4093 quad op amp and an
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SG3524 pwm ctrl chip, with 25KHz pwm outputs going to the V(in) motor pin. Replaced both chips and a couple of SMT resistors. Works now!Also see my
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for more repair articles on lab instruments.