Hi there,
I work for an archival company in Australia and as such I work with cameras much like yours on a day-to-day basis. There could be a number of reasons you camera is doing this. First the simple things:
Check to make sure your camera is in playback mode. A black screen with timecode signals to me that you may be in 'camera' mode rather than in the playback mode. Switch your camera into "player" mode. After doing this make sure your tape is rewound all the way!
Next is to check if your tapes are blank. I have found before that some of my clients have labelled tapes but have not recorded any footage to them. This may result in a black or blue screen with no timecode ticking over.
Also make sure that the tape and the camcorder are compatible. If you have a video8 or hi8 camcorder and a digital8 tape it may not playback in your camcorder. Symptoms of this vary from player to play and yours might just display a black screen.
If you do not believe the tape is blank you may need to clean the playhead or "drum" in your camera as it may be dirty and not reading the tape properly.
I would highly recommend you send the camera in for repair or have your tapes digitized by a proffessional at this stage as these old tape cameras are notrious for being tricky to repair and clean. But if you are game there are plenty of tutorials online on how to clean the playhead of your video8/hi8/digital8 camcorder. DO THIS AT YOUR OWN RISK. If you damage your camcorder it may never work again!
If you exhaust all of these avenues then you have to bite the bullet and buy another, working camcorder as it would most likely be cheaper than trying to get your current one repaired!
Goodluck!
- Mitch