Entertainment Center: TVs, Stereos, VCRs and DVDs - Phillips 36" tv problems

Hello,

I have a TV repair question you folks may be able to help me with. I have a Phillips 36PT71 B129 TV that is giving me trouble. At first, it would just come on by itself sometime during the night. After a while, the volume bagan going down by itself, as if you were holding down the volume down button, but no-one was. We removed the batteries from the remote with no change.

Now, sometimes the TV won't come on with the remote or the panel buttons. Sometimes it will come on by itself though, or sometimes it won't change channels or volume. The workaround is unplugging it. Often, unplugging it for a period of time and then plugging it back in gets it working right again. Sometimes not. Sometimes we can't turn it off at night. Sometimes when it's not working, you can unplug it and a few seconds later, some sound comes from the speakers (not static, but actual sound from programming). Right now, it's not working at all. We unplugged it, but it only makes some sound momentarily when you plug it back in, but does nothing when you hit the power button.

It doesn't seem to respond to bumping/flexing or movements that would manipulate a cracked or loose connection or board. I haven't removed the back yet, as I would like to have a good idea of what I'm looking for when I do.

I have some electrical test and repair equipment and have some knowledge of electronics, but I am not an expert by any means. I saw several folks asked about the same problem on a different site, so apparently this is a somewhat common problem. There weren't any helpful replies there, however. Hopefully you folks here can help me figure this one out!
Thank you in advance!

I have heard of this problems a few times on this board, but no one has ever replied back as to what was wrong.

I would assume it has something to do with either the IR eye, or the control panel itself.

Could you move this TV to a different part of the house to eliminate some "outside" source from interferring with the IR frequencies?

Have you take some compressed air and attempted to clean out the buttons on the set?

Could you move this TV to a different part of the house to eliminate some "outside" source from interferring with the IR frequencies?
Easier than that: Tape over the plastic cover of the IR receiver with several widths of electrical tape. If it works using only the TVs buttons, you know it's an IR issue.

I have covered the IR receiver with no different results. I haven't attempted to clean the buttons yet. I don't know if it matters or not, but when it acts up, it may affect all the buttons, or one. When it acts right, the buttons all work. It would seem odd for all buttons to suddenly give trouble at the same time...right? Or not?

I'm thinking the control board too... I'm assuming when I open the back, I can identify the control board by looking to see which board the IR eye wires go to?

take the batteries out of the remote for a day and see if it will reboot - or try a different remote all together.

are you using a universal remote that might be programed in with another TV's remote code?

It kinda sounds like a button is stuck down or something (dirt or crumbs) is inside keying the buttons either in the remote or TV

I bought a 20" Philips-Magnavox TV two years ago that turned on and off just fine from the remote, but invariably, in the middle of the night, I'd wake up to discover the TV had turned itself on. The only way I could make sure it stayed off all night was to unplug it for a few minutes, then plug it back in. After doing that, it would stay "off" until the next time it was used. However, once it was used again, it would repeat the "middle of the night" turning-on-by-itself routine. I tried everything, including taping over the IR sensor, and could never figure out what was triggering it. I finally returned it to the store I bought it from after putting up with its antics for over two months.

I know that doesn't help YOUR problem very much, but I wonder if there is an inherent problem with Philips remote control systems?

The most likely problem is the "small signal board".It's been known to cause all kinds of crazy problems in philips tvs.The part # for your tv is 313917863191 .The good news is that it's an easy DIY fix.The module will be on the left side of the tv looking from behind the set.It looks like a computer PC board.They are available at sears parts.You can get one at
matelectronics.com for dirt cheap but I have never used them before.:thumbup:

Awesome! That is just the kind of reply I was hoping for. I just got back from vacation, and the set is working well now. (It was unplugged while we were gone). I'm sure it will probably start acting up again, and if it does I'll open it up and have a look at that board and connections. If I don't see any obvious problems with it, I'll probably order one. I'll post back with results if I do this.

Thank you very much for the advice and even looking up the part# for me!:thumbup: