I have a few DVD+R dvds that I had partially recorded on, but not finalized yet. Now When I put them in it says loading and then says Unknown disc. However it loads movie dvds bought in stores just

There are a few possible reasons why your JVC 150 DVD recorder may be unable to finish a disc or is displaying an error message indicating that a disc is an ad:
Compatibility of the disc: Not all DVD recorders are compatible with all DVDs.
Your JVC 150 DVD recorder might not be compatible with the DVDs you've used for years.
A dirty lens may prevent the DVD recorder from adequately reading the disc.
Even if a lens cleaner helped, if the issue still exists, it might be required to have the lens cleaned by a trained expert.
The CD might have been scratched, damaged, or otherwise corrupted, rendering it unreadable.
Firmware issue: The firmware of the DVD recorder may be outdated or malfunctioning, causing it to not be able to read or finalize certain discs
Hardware issue: There may be an issue with the hardware of the DVD recorder such as a malfunctioning laser head or reading mechanism that is preventing it from reading or finalizing discs.

Either a DVD with the wrong region code has been loaded, and your player doesn't recognise it, or you have inserted a disc which is either rewritable (or an incompatible format for your player), a blank DVD or CD, or the disc has not been finalised in a DVD recorder. It depends on the disc(s) you have, whether they are region coded or those using a compatible playback format (finalised DVD-Rs are the best as far as burned copies go).

Examples of incompatible formats for your player may include;
DVD-ROMs
DVD-RAMs (which are the wrong version/speed for your unit)
Mini-DVDs/CDs
CD-RWs
DVDs with a different region code to your player or rewritable discs

* When using shop-bought DVDs, including those purchased online, make sure their region code matches your player.

The home recorded dvds disc have diffrence finalizing codes,that the Panasonic dvd recorder doesn't share those codes.That why u can't play those home recorded dvds discs.

Insert one of the recorded disc and try to finalize. If it accepts, that means they are not finalized.

You have to finalize the disc. if the disc goes to the end it will finalize the disc automatically. If there is some part of the disc not used you have to do it yourself. IN DVD MODE PRESS SETUP, THEN DISC EDIT, THEN FINALIZE. FINALLY PRESS YES. That should do it.

DVD & CD use different wavelengths for the read head. I suspect that the blue laser is out of alignment or otherwise in need of repair.

PhotoCD is a format.

DVD-Rs do work with the RDR-VX500 ...... I had not recorded on mine for a few months after I ran out of the last batch ....... then I tried recording on the newer Sony DVD-Rs I had ...... would not record on DVD-R ..... turns out the instructions say the recorder will not work with any DVDs faster than 8x .... It looks like it's recording but it doesn't ..... then I noticed the newer DVDs were 16x ...... found an old 8x and tried it and it works fine ..... turns out the unit won't record slower on a 16x, it just won't record at all ...... get 8x and you'll be ok

I had the same problem, some dvd-r's went faulty when the RH-299 couldn't finalize them. Problem fixed when the DVD readhead was replaced.

machine might only take - dvd or + dvd only some take both types will show on front of machine just a thought

OKAY GUYS TRY USING THIS VERY COMPATIBLE MEDIA

(MEMOREX BRAND DVD-R) THIS WILL SOLVE A LOT OF YOUR PROBLEMS