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[poursha]

I've been trying to figure out how to mod an ss13a switch into a 4-button switch, instead of 3-button and dim/bright.

I figured that I'd look at the guts of a kr22a (4-button, dim/bright) credit card remote and see if it was similar; used the same chipset.

Sure enough it DOES.

In fact, I've pulled both schematics from the FCC, and the they are almost identical. But, I can NOT get it to work with the 4th button. I've tried shorting about every combination of pins that makes any sense. Everything that I try just transmits an A1 (first button command), instead of an A4. <argh>

Here are the two FCC locations for these remotes:

https://gullfoss2.fcc.gov/prod/oet/cf/eas/reports/ViewExhibitReport.cfm?mode=Exhibits&RequestTimeout=500&calledFromFrame=N&application_id=94285&fcc_id='B4SSS13A'

https://gullfoss2.fcc.gov/prod/oet/cf/eas/reports/ViewExhibitReport.cfm?mode=Exhibits&RequestTimeout=500&calledFromFrame=N&application_id=92983&fcc_id='B4SKR19A'

Is anyone smart about RF circuitry? What is the trick???

RoB

[gil shultz]

Good Evening,

Your links did not work.  I am just guessing but the wire you used is probably changing the RF frequency causing the receiver to miss the signal.  Remember these are very low cost items not designed for modifications or circuit changes, there are no extra parts to stabilize the system.

Good Luck
Gil Shultz

[TakeTheActive]

...I figured that I'd look at the guts of a kr22a (4-button, dim/bright) credit card remote and see if it was similar; used the same chipset.

Sure enough it DOES.

In fact, I've pulled both schematics from the FCC, and the they are almost identical. But, I can NOT get it to work with the 4th button...

...Here are the two FCC locations for these remotes:

• SS13A Schematic - FCC ID: B4SSS13A
  
  
• KR19A Schedmatic - FCC ID: B4SKR19A
  

...Your links did not work...

For future reference (as of 09/22/2007):

• Federal Communications Commission (FCC) Home Page
  
• FCC Registration Number (FRN) Commission Registration System (CORES) - FRN: 0006694954
  
• FCC ID # Search Tool
  
  
• Office of Engineering and Technology Exhibits List (Detail) for FCC ID: B4SSS13A
  
• Schematic for FCC ID: B4SSS13A
  
  
• Office of Engineering and Technology Exhibits List (Detail) for FCC ID: B4SKR19A
  
• Schematic for FCC ID: B4SKR19A
   - ERROR: FCC LINK goes to WRONG schematic!?!
  

[Puck]

In fact, I've pulled both schematics from the FCC, and the they are almost identical. But, I can NOT get it to work with the 4th button. I've tried shorting about every combination of pins that makes any sense. Everything that I try just transmits an A1 (first button command), instead of an A4. <argh>

poursha: This device contain the EM78P153 microcontroller. It has a One-Time-Programmable (OTP) Read Only Memory (ROM) section that is programmed to operate in a specific way. If this same microcontroller is used on more than one devices, then it is more than likely programmed differently as well.

This programming would have been done by the manufacturer and cannot be changed to alter how it works.