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Author: Subject: Ika cmag hs7 fried circuit
bnull
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[*] posted on 10-7-2024 at 04:11


Unplug the black cables from the motor, test for continuity, measure resistance and then plug the wires back.

The capacitor seems to give continuity while on the board because the continuity is of the circuit of which is part. A capacitor on its own, plugged to nothing else, gives a resistance value that increases and goes off the multimeter scale. A value below 1 megaohm means it is shorted inside and should be replaced.





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[*] posted on 10-7-2024 at 05:03



The capacitor looks OK, maybe poorly fitted.
But, if removed and tested with an Ohm meter, (short/discharge before testing)
it should be a near short circuit initially, rising to 10's or 100's kOhm (leakage current), as it charges up.
If it has a continuously low resistance then it's toast.
Polarity matters!

The motor winding also looks OK but that's not conclusive.
I can't remember, but I'd guess 100 Ohms dc for the winding, but could be an order of magnitude out,
anyway, some dc resistance not in Ohms or megOhms.
You can probably just measure directly between the terminals on the motor as-is.

120 Volts, 35 Ohms: Power = 411W..... maybe,
Do you trust your Ohm meter readings?

Oops! repeat of above, I'm too old and slow ;)

[Edited on 10-7-2024 by Sulaiman]




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[*] posted on 10-7-2024 at 06:24


Quote: Originally posted by Cendre  
Edit 2: looks like that transformer is “obsolete and no longer manufactured”. Is there another component I could use to replace it. I wasn’t able to find the exact model sold anywhere.
(In Europe)

I think you can use a 230 V model (030-7342) in place of the 115 V (030-7030) (same specs and pinout) and dispense with the 115 V outlet. Which leaves us with the heater problem.

The heater is rated to 115 V but, if it is damaged and buying a replacement is still better than buying a new stirrer, a 230 V, 1000 W heating element is suggested. Unless IKA cheated and used a ~400 W element; who knows.

Edit: The motor is a 120 V shaded pole motor (https://www.ika.com/ika/product_art/spareparts/3581201.pdf). It may have been damaged too. Crap.

If the transformer, the heater and the motor are damaged, you can either look for replacements (notice that IKA sells no transformers, only heater and motor) or buy a new stirrer/hotplate. My crappy solution would be to buy everything 230 V: transformer, motor, and heater. The only parts of the circuit that deal with mains voltage are the phototriacs, the transformer, the heater and the motor. The maximum allowed in the phototriacs is 600 V, so they're fine.

There may be some other components between plug and transformer, such as capacitors and whatnot, that need a checking. I wish I could help more.

Edit2: In case heater and motor are both damaged, together with transformer:
  1. Block has a 230 V transformer with the same specs of the original. Available at Reichelt for € 5.60 (https://www.reichelt.com/fr/fr/transformateur-2-3-va-12-v-19...). I haven't seen an 115 V model yet.
  2. The motor is a shaded pole motor (230 V: SKU 3525900; 115 V: SKU 3525901). Originals from IKA sell for about £ 68 (230 V) and £ 78 (115 V).
  3. Heating foil 230 V (SKU 5004800) about £ 96. No sign of 115 V (SKU 5004801).


If you decide to convert the stirrer to 230 V, it will cost about £ 170 or € 195 (according to the prices practiced by The Laboratory Store Ltd), not including shipping taxes. You will probably get a lower cost from sellers in mainland Europe. Attached below are the lists of spare parts from IKA for both 115 V and 230 V models.

Attachment: IKA c-mag HS7 spare parts 115 V.pdf (1.5MB)
This file has been downloaded 8 times
Attachment: IKA c-mag HS7 spare parts 230 V.pdf (1.5MB)
This file has been downloaded 10 times

[Edited on 10-7-2024 by bnull]




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[*] posted on 10-7-2024 at 13:04


Lets say the psu, motor and heater are all damaged. Using non-ome parts, your looking at a cheap fix.
You could spend a lifetime trying to find parts that fit or an hour with a tap tool, alumnium sheet and some glue

Mains to 12vdc, give you a peak voltage of about 17, at 200ma, 2.3va = around 13vdc. Most the chips parts have listed on that board max out at 18-25v so there is room to play around and find out. disconect the questionable psu and install a new one, little bit of wire and solder, no worries.
Universal input voltage: 85-264V AC or 110-370V DC. 2000ma peak 1400ma continuous. Ive used a lot of these.

The motor will be the hardest find, if its a nema style, then your on easy street. If not id look at the manufacturer's documentation for suggested replacement parts


[Edited on 10-7-2024 by Rainwater]




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