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View Full Version : Hacking an extremely sensitive Hz issue (50 vs 60)







marcus2000
06-11-2012, 05:41 AM
I have been troubleshooting this problem for 10 months now and I'm ready to give up. This is about making an 60 Hz whirlpool appliance imported from America work on 50 Hz in Japan. The dishwasher's control panel is extremely sensitive to the Hz. I've not seen this with anything else ever. Usually the clock simply is off and all appliances work otherwise. But, this won't even power on without 60hz.

I bought a $2300 power converter and plugs into the wall and takes the 100 v and 50 hz input and puts out 115 v and 60 hz. I've used a Kill-A-Watt to measure the Hz real time.

Inevitably, the dishwasher only finishes about 20% of the attempts we try from beginning to end. When it stops, it starts the whole cycle from the beginning. I've taken video of the Kill-A-Watt and when the Hz fluctuates for a micro second from 60 to 57.5, and then back to 60, then dishwasher stops.

This is very frustrating and now I'm considering breaking open the motherboard of the dishwasher and figuring out someway to hack a resistor or something onto it to bypass this 60hz only behavior. Any advice out there please?

Brian_UK
07-11-2012, 12:37 AM
Sorry, but being a forum relating to refrigeration we may not have many experts dealing with dishwashers.

Yuri B.
07-11-2012, 07:22 PM
Hello
Possibly it is now the new bought converter' unstable work that is making it worse.
As for the dishwasher, all controls use DC's, not the AC. I would try to figure out at which points on its PCB the DC source(s) start, then would throw away the trafic, rectifiers, stabiliser and whatever there is and connected to this point(s) my own source of well rectified stabilised DC (as in principle it does not matter from what kind of electricity I have obtained a necessary voltage level).

install monkey
07-11-2012, 10:20 PM
dish washer start sequence is fill, heat if req, then wash pump - cold rinse then drain, is it sotpping when the wash pump starts causing a dip in the frequency

chilliwilly
12-11-2012, 01:38 AM
dish washer start sequence is fill, heat if req, then wash pump - cold rinse then drain, is it sotpping when the wash pump starts causing a dip in the frequency

Hot rinse! glasses might break with cold water and its the sanitising cycle (75 deg+).

This is typical when people move abroad where there's a different distribution and wiring system. They really should purchase new appliances instead of power VF converter units.

Homes in North America have a 220-240/110/120v 3 wire (2 of 3 phase) distribution and neutral feed to them. So a warewasher will usually have a 2kw + power rating, and will require a 240v 3 wire feed to them. Like Yuri B says once the power has been transformed and rectified to the pcb voltage, frequency shouldn't matter.

Are you sure that converter of yours has a 220-240 v 3 wire output and not a 110-120v 2 wire? If that's what it has then its the wrong one and probably will only power brown goods but not white goods.

What make and model is it any way?

marcus2000
12-11-2012, 03:33 AM
Sorry, but being a forum relating to refrigeration we may not have many experts dealing with dishwashers.

Yeah I'm sorry. It's just I saw some really smart posts earlier about Hz and Volts, and this situation is kind of independent of the appliance anyway. Sorry to bother you.

marcus2000
12-11-2012, 03:40 AM
dish washer start sequence is fill, heat if req, then wash pump - cold rinse then drain, is it sotpping when the wash pump starts causing a dip in the frequency

Good question, but no. It stops at anytime. It is not predictable and it will stop anywhere. The transformer / Hz converter is not stable, and has nothing to do with the appliance plugged in. I've had a kill-a-watt measuring device plugged into (as if it were the appliance) it with no appliance plugged into the kill-a-wall (so no power draw at all). And after awhile the Hz will fluctuate just slightly off of 60 Hz for less than 2 seconds. It'll drop down to 57.5 and then back up to 60. The dishwasher dies instantly when the Hz fluctuates even slightly off of 60 Hz. Also, the Kill-A-watt resets often...as if it were pulled out and plugged back in. The output power from the converter is simply the source of the problem. I'm having trouble getting their attention to help with this so basically giving up on the converter as the solution.

marcus2000
12-11-2012, 03:46 AM
Hot rinse! glasses might break with cold water and its the sanitising cycle (75 deg+).

This is typical when people move abroad where there's a different distribution and wiring system. They really should purchase new appliances instead of power VF converter units.

Homes in North America have a 220-240/110/120v 3 wire (2 of 3 phase) distribution and neutral feed to them. So a warewasher will usually have a 2kw + power rating, and will require a 240v 3 wire feed to them. Like Yuri B says once the power has been transformed and rectified to the pcb voltage, frequency shouldn't matter.

Are you sure that converter of yours has a 220-240 v 3 wire output and not a 110-120v 2 wire? If that's what it has then its the wrong one and probably will only power brown goods but not white goods.

What make and model is it any way?

There is no 220 volt concern anywhere in the system. The original appliance is American 115ish volt 60 Hz. The power out of the wall is 105v 50 Hz. The transformer converter puts out 115v 60 Hz signal. The dishwasher worked for months, but then the converter started to become unstable in it's output. 99.999% isn't good enough, because the slightest 1 second variance of 60 Hz down to 57 Hz will kill the dishwasher. With a purely motor appliance like disposal or refridgerator, no big deal. With a cycle appliance like dishwasher, it's instant death to the full cycle. And here is another problem...when the converter goes unused for 2 weeks, it'll work the first two days. Then like clockwork it'll start becoming unstable. It's very predictable. I've video taped the whole process to try and prove to the manufactorer it's their converter's fault.

marcus2000
12-11-2012, 03:49 AM
Hello
Possibly it is now the new bought converter' unstable work that is making it worse.
As for the dishwasher, all controls use DC's, not the AC. I would try to figure out at which points on its PCB the DC source(s) start, then would throw away the trafic, rectifiers, stabiliser and whatever there is and connected to this point(s) my own source of well rectified stabilised DC (as in principle it does not matter from what kind of electricity I have obtained a necessary voltage level).

This! This is the last ditch effort solution I am looking for. Can you help me and walk me through the steps to do this. I'm happy pay for your consultation/expertise.

chilliwilly
12-11-2012, 04:33 PM
There isn't much more on a dishwasher load wise what you wouldn't find on a fridge, the boost/wash pump is probably the only thing that would cause a surge. Are you sure its working ok? If the capacitors gone s/c, then the vf unit will see a o/l, or if it has gone o/c. Some of the older designed vf units will ramp up until they sense a power demand, and then result in a trip condition.

Yuri B.
12-11-2012, 08:56 PM
My post was only a bit of advise, by that I am in no way a big expert, unfortunately. And, as this forum is indeed dedicated to refrigeration, on the place of the OP I would turn to electrical /electronics ones, for instance, CR4 (Electrical Engineering division). BTW, I strongly believe the latter was done already as engineering thinking and determination are evident from his posts.

install monkey
13-11-2012, 12:01 AM
hot wash, cold rinse

install monkey
13-11-2012, 12:05 AM
have u tested the inulation of the wash pump,incase its grounding/earth leakage, and thus occasionally tripping. you stated that it can work for 2 days , or maybe an occasional drip onto electrical components,- if all is ok then it could be the converter. good luck