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sottrits

Feb 14, 2018
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Hi there guys,
you make a good job here...
I have to fix a diathermy medical unit ITO PM-800s. It is something similar to a microwave oven for heating points of the human body.
http://www.medwow.com/med/diathermy-unit-physical-therapy/ito/pm-800s/6869.model-spec
this unit has a part that I could not idenify, it is possibly a resistor but I can not identify the resistance.
I upload some photos of the part, and the mainboard where it was soldered (R9 possiton).
the resistor seems to be burned, I take nothing from my multimeter.

thanks in Advance.
 

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Harald Kapp

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As this is a medical device you should get the original part from the manufacturer for reasons of safety and liability.
 

sottrits

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As this is a medical device you should get the original part from the manufacturer for reasons of safety and liability.
the manufacturer asked for 2000 euro for a new mainboard. I asked if somebody can identify what resistor is this in order to find the same one...
 

Tha fios agaibh

Aug 11, 2014
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Looks like a high voltage thick film resistor. But idk what the numbers mean. Can you get the schematic?
 

sottrits

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It is on a 4KV part of the mainboard...I could not find a schematic on internet and the manufacturer does not giving any information...
 

hevans1944

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...the manufacturer does not giving any information...
Of course they don't. Why pass up the opportunity to sell a €2000 Chinese-manufactured circuit board instead of a €2 high-voltage, thick-film, resistor? And then there is the CYA medical liability issue to consider... what if, in attempting to repair this POS import, you cause it to operate in a manner that is undesirable and dangerous to the patient? Who is going to pay the damage penalties for that? Most medical device manufacturers will not only NOT provide service information, they won't even sell you the parts needed to perform repairs... assuming you can identify a part number to ask for.

From what is visible on the circuit board, resistor R9 appears to be connected between the positive and negative power supply output terminals. It probably functions as a "bleeder" resistance to discharge energy stored in the power supply capacitors. Four kilovolts at a guesstimated one milliampere of bleeder current would require a power rating of four watts (P = VI) and a resistance of four meg-ohms. (R = V/I). And it must not "arc over" when 4 kV is applied across the terminals. Good luck finding one of those. Even better luck required to find one approved for use in medical electronics. Try looking here first.
 

shrtrnd

Jan 15, 2010
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Have to agree with Harald Kapp and hevans1944.
I don't know how it is in Greece, but here in the US if somebody suffers adverse effects after medical treatment, they sue the hell out of the medical provider. Even if you fix this board correctly, if something ever goes wrong with a patient and the investigators find-out you 'tampered' with the apparatus, You're 'cooked'.
'Saving' money over this can potentially cost much, much more later.
 

hevans1944

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'Saving' money over this can potentially cost much, much more later.
Truth!

Probably no one here remembers the "good ol' days" of medical electrical and electronic quackery... it was a free-for-all of unlicensed practitioners using questionable devices to "treat" patients for every imaginable condition or disease. Testimonials abounded. but little scientific evidence for the efficacy of the machines was provided. Training was non-existent or consisted of a few hours (at the most) of a demonstration/sales pitch. X-ray and diathermy machines were unregulated. Induction or "shocking" coils seemed to be popular, probably because they were cheap to make and produced no lasting effects, other than by the placebo effect. When the U.S. Government decided to regulate the market, set standards for performance, and require a medical degree to prescribe or operate the equipment, things settled down a bit.

For example, shoe store fluoroscopic x-ray fitting vanished, virtually overnight. I remember using one in the early 1950s when my parents fitted me for new shoes. I was not tall enough to peer through the eye ports to observe on the green fluorescent screen the x-ray shadowgraph of my feet inside the shoes, but my parents were. So I got a pair of well-fitted shoes.

Today, with image-intensifying and digital image capture "screens," the x-ray radiation dosage would be quite small and probably safe enough for several dozen "shoe fittings" per year. But, AFAIK, no one has tried to market the new technology to shoe stores in the shopping malls of America yet... probably because it is difficult to find a shoe salesperson who also has a medical degree and a license to practice medicine.

Another therapy I wish I could purchase at a local hardware store is a muscle stimulator. I was treated with one of these after I broke some bones in motorcycle accidents. Very pleasant experience, but the only source of similar equipment available today appears to be in the form of an electrical sex toy... no doubt sold as a novelty item for amusement only. Similar to a TENS unit, that I see is now available for sale off-the-shelf and over-the-counter at Walgreens and online through Amazon and other retailers.
 

davenn

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It is on a 4KV part of the mainboard...I could not find a schematic on internet and the manufacturer does not giving any information...


I agree with the other responders

and add
If you are not qualified/certified to work on repairing medical equip. Then PLEASE get the unit to a qualified repairer


thread closed for safety reasons
 
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