# Massage Chair Hand control Problem

Discussion in 'Microcontrollers, Programming and IoT' started by Jim Bunting, Sep 27, 2017.

1. ### Jim Bunting

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Sep 27, 2017
I have spent several years repairing all makes of massage chair. I have learnt that even with the same model, electronics can change. When replacing a hand controller I have always checked to see that the frequency of the crystal on the main board matches the frequency of the crystal in the hand controller. Recently I received a chair which failed to respond to the hand controller – checking all parts everything seemed OK. However when I looked the frequency of the hand controller is 11.0592 whilst the one in the chair is 4.0000. With very little or no understanding of how these things really work – this makes no sense to me. My only explanation – could a previous attempted repair have resulted in a mixing up of handsets? I’ve been there before and it’s very time consuming. Is something very wrong or am I worrying about nothing.

2. ### 73's de Edd

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Aug 21, 2015
W e l l l l l l l the 4 mhz is a VERY common . . . .clock oscillator frequency for u/p's.
And if you check out the 11.059200 it will prove to be binary divisible by 2 until it gets all of the way down to 675~ at which point they may be further dividing on down by by powers of 5's.

You certainly HAVE to give us the the brand and model involved or else its as cryptic and involved as your telling us
" I have this Ford car . . . . "

3. ### kellys_eye

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Jun 25, 2010
There is no reason why the crystal frequencies should match - why would you make the assumption that 'matching' is a requirement for 'working'?

4. ### Jim Bunting

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Sep 27, 2017
I don't think my question was at all cryptic - ignorant perhaps? My question was simply about whether it was necessary to match crystals. As said, when we have accidentally mixed identical hand controls with different frequencies they do not work unless the frequencies match. It seems however they do not 'have' to match. A simple explanation of what is required would be useful to me. I can see how different but divisible frequencies can work but not indivisible frequencies. My arithmetic too is poor - I divide 11.0592 by 2 down to 27 but what then - seems an odd factor to me, but that's why I asked.

5. ### 73's de Edd

2,922
1,235
Aug 21, 2015
Sir Jim Bunting . . . . .

You certainly HAVE to give us the the brand and model involved or else its as cryptic and involved as your telling . . . . . . .

That aspect was solely being relevant to our not having been given the brand and model of unit.
I think that the crystal frequency is soleley related to the clock oscillator of the microprocessor of the unit
On inspecting the crystal leads of the chairs units microprocessor circuitry do they seem to have untampered original factory solder on them .
Therefore . . . with no one having resoldered or messed with its two connections.

On your hand remote unit . . . . . is it using interconnecting cabling with hard wiring, infrared or possibly RF tecnology as its handshaking medium.
If being of the latter two technologies. . . . have you inspected the insides of the remote hand unit ?

73's de Edd

6. ### Jim Bunting

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Sep 27, 2017
I cannot give the model or even the manufacturer. It is however most likely an early chair by Zhejaing Haozhonghao Health Product Co.Ltd. now iRest as it has many internal similarities to Rongtai, a previously associated company (who always have matching crystals) The hand control is hard wired and it is presumably simpler if the frequencies are the same… The main control PCB and the hand control PCB have not been messed with…

7. ### Jim Bunting

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Sep 27, 2017
Further - Somebody could have accidentally swapped handcontrols as it seems it hasn't worked since a previouse attempted repair some years ago. I have personally made this mistake - silly but easy and expensive.

8. ### rockland

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Feb 26, 2019
i am looking to replace my hand control panel, since i have to hold the on button longer and press harder each time to get it to power up, looking for new or used, easy fix since it just plugs into the bottom side, next to key, and main power switch. this is what the panasonic panel says not sure of make/model. model# EP3513 panasonic lounger AC120V 60Hz 210W Matsushita electric works

9. ### rockland

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Feb 26, 2019
looking for repairman, or service in dallas area. feel strongly its the "ON" button has been pushed too much. but i will pay a service call and parts, cause its a great chair, one owner, and keep it in good condition, every once in a while i go push it and it will work, if i push hard enough or push it several dozen times. suggestions?

10. ### Jim Bunting

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Sep 27, 2017
The most likely fault is not the Hand Control, but the connecting multicore wire. One of the cores breaks but touches sometimes when moved. 10 mins work with a multimeter will probably solve the problem.

rockland likes this.