Citizen C27604HD not receiving IR codes

[neilc6]

This TV appears to use the same hardware as Viewsonic N2751W which I have found a service manual. Initially, the TV had bad caps and a bad Q7 and ZD4 which I have replaced and got the power back up. The remote can be used to power the TV on but at that point, all signals are ignored. There is 5V and pulses are detected at the IR receiver output with my meter.

There is a remote keycode (power, up and enter at the same time) to bring up the service menu but this isn't working with the TV on or off. I would like to try a factory reset but can't get into the menu.

The application circuit for the IR receiver datasheet shows a RC filter for VCC but this circuit is on the main board and not the IR board which is connnected through 18 inches of cable. Don't have a scope to see if there is noise pick up from the wires after the filter since it would make more sense to have the filter on the IR board. There is also an optional >10K pullup which on this board is only 1K.

Suggestions??

[dskall]

Re: Citizen C27604HD not receiving IR codes

Is that the original remote? Do buttons work?

[neilc6]

Re: Citizen C27604HD not receiving IR codes

Yes it is the original remote. The only signal that it responds to is power on when it is off. Once on, no remote functions work including power off. If I manually power off, I can turn on again with the remote. Remote buttons are sending signals viewing the remote LED with a camera and the output level drops probing the IR receiver output pin with a meter.

[dick_barton]

Re: Citizen C27604HD not receiving IR codes

Have you tried fresh batteries in the remote?

[neilc6]

Re: Citizen C27604HD not receiving IR codes

Yes, the batteries are fresh and measure 1.5V each.

[vinceroger69]

Re: Citizen C27604HD not receiving IR codes

page 18 of the user manuals mentions factory reset but not sure if you can use the tv buttons to get to the section
https://www.manualslib.com/manual/73...page=18#manual

[neilc6]

Re: Citizen C27604HD not receiving IR codes

Thought I tested the service menu button key code before on the top buttons but tried it again with the TV on and it worked. Went to "EEPROM init" and remote is now working. Key code is "power", "up" and "Enter" pushed at the same time with the TV on.

[dick_barton]

Re: Citizen C27604HD not receiving IR codes

So all working now?

[neilc6]

Re: Citizen C27604HD not receiving IR codes

Yes it is all working. I probably tried the keycode with the remote and not the front panel buttons before. TV should be on and set to TV input. The TV has some peculiarities - analog tuner only, menu only displays on tv input, input needs to be selected vs cycling through each one.

[dick_barton]

Re: Citizen C27604HD not receiving IR codes

Thanks for the update which could prove very useful to anyone else with a similar problem.