Repairing an IKA stirplate RET Basic, magnetic hot plate
IKA stir plate RET Basic, Won't stir. Water spill under motor, destroyed SMT resistors and traces. https://www.ika.com/ika/product_art/...ts/3188801.pdf IKA partslist gives the part nos. for this model The 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. https://ebmpapst.com/media/content/i..._ESM-iQ_DE.pdf 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 https://www.st.com/en/power-management/sg3524.html 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 http://staff.washington.edu/wbeaty/chemtrik.html for more repair articles on lab instruments. |
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