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Hotel mode and child locks are often the bane of my existence. I've scrapped many otherwise working sets that were stuck in either mode simply because it was impossible to return them to normal operation without the missing remote (and a universal failed to activate the necessary menu). Sometimes I've gotten around this by changing out the RAM IC with one from a similar chassis, but often there are enough differences that while this will unlock the set it leaves other settings corrupted. I could attempt reprogram the IC with a PC based programmer, but so far the sets I've found in this state haven't been worth the effort.
At least some sets have the decency to power up and display a lock symbol or message. Others won't even power on. Just recently a Teac/Vestel 16:9 set had me confused in just this manner. I was almost ready to swap out the microcontroller when I remembered they had this "feature" and found a remote that would unlock it.
I've had a few of those late 90s 14" trinitrons without AV inputs here. The ones that I found do not have a live chassis. I have added AV inputs to one in the past. It is a hack job as the microcontroller can't select AV so you have to connect a switch to the select pin on the jungle IC (or just hardwire it if you don't need the tuner). I didn't bother to document the process, but that datasheet for the jungle IC makes it obvious.
Otherwise, the latest set I remember finding here without an AV input was a 1997 Sanyo 21" American set that someone must have brought over with their personal effects not realising it was completely useless here. I found it strange that such a late model stereo set lacked such a basic feature. It made more sense when I opened it up and found the live chassis.
I've got a little 5" AWA that was a hospital rental set that I think I've posted here before. In order to prevent patients from bringing their own set (or stealing the rental sets) it was fitted with a strange triaxial connector that carried DC power and the RF input. Internally it was fitted with a DC-DC converter that took 32VDC from this connector and supplied 12VDC to the chassis. The original AC/DC connectors, RF connector and AV connectors were fitted to fill the holes in the cabinet, but the related circuitry is missing (not removed, it was never fitted). I've since removed the DC-DC converter and reconnected the original DC and RF connectors. It now runs from a 12VDC supply and accepts a standard antenna input, but I've yet to fit the missing AC power supply or get the AV input working.
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