NEC DS8000U VCR where to find manuals? Belts? Codes?

[n8nagel]

The counter was no longer advancing, but the display still had the forward arrow indicating play mode.

However you make me think. The counter on this has two modes, "real time" and "normal". Pretty sure it was in "real time". Is that based off of inches of tape fed through, or is it somehow embedded in the tape like the closed captions? If the latter, maybe I should try it again in "normal" as it's entirely possible that the tape was still moving but I couldn't hear it. Seems unlikely, but possible.

Edit: this could be why the tape is still held against the drum in FF and REW?

[Electronic M]

You're making some right and wrong assumptions...
Top loader era VCRS used a mechanical counter tied to the drum reel which advanced a certain number based on take up or feed reel rotation. The normal count is designed to mimick that. Later decks usually used the linear control track to perform Real Time Count and to perform tape counter indexing. VHS tape is typically divided into 3 sections...2 thin stripes along an edge for the linear audio and linear control track read by a fixed head like an audio cassette, and then there's a 3rd region that comprises most of the width of the tape which contains a series of diagonal stripes of video information from the spinning head drum.
If it's reading only the control track then unrecorded sections of tape won't advance the counter even while playing.
Better mechanisms have 3 states to threading: 1.) completely in the cassette, 2.) Capstan and linear head only (Stop-fastwind mode), and 3.) Video drum, capstan and linear heads (playback and visual search). If your mechanism doesn't have state 2 and reads counter off the control track then it has to keep everything threaded to maintain tape count.

The control track was initially a IIRC square wave tone signal designed to aid the head drum and capstan servo in duplicating the tape speed and phase and the head drum speed and phase such that the video head would be able to correctly trace the recorded video stripe (instead of say tracing between 2 stripes and getting noise) when LP and EP/SLP came out the frequency of the tone could be used to figure out which speed, and as digital electronics got affordable engineers started using those digital electronics to count those pulses which were directly tied to frame rate and there's 60 frames a second...So accurate time could be kept (as long as there wasn't long unrecorded static between recorded portions). Eventually they even added indexing to the control track and made provisions to dub index marks in and out.

[n8nagel]

Thanks for the explanation Tom. I really did try to Google this stuff but didn't find much, I now know a crapton more about these things than I did before. So, I popped the covers off this thing again and what did I find?

1) The tape only wraps around the drum in FF and REW when the counter is in "real time" mode not "normal" mode. Now that I know there's a drum and a linear head, I've ID'd the linear head, but on this unit there appears to be no intermediate stage to engage only that head and not the drum. So: lesson, don't leave the counter in "real time" mode when rewinding unless you have a reason to do so.

2) If I leave the counter in "normal" mode, and play or FF the tape to the end, it stops and begins rewinding. I have not seen what happens in "real time" mode with the cover off so I can 100% verify that it has reached the end of the tape. I'm checking that now. So, so far, no problem identified.

3) Unfortunately, while the unit appears to play and REW fine, in FF mode I think the big roller that engages the take up reel is slipping. I've tried to clean it a little but it's not doing the do. What to do here? Would that be the "Idler Assembly"? There is a PRB part for that and also just the tire.

4) the high pitched noise coming from the drum area is now not going away within a few seconds when I start it anymore, it's taking longer and longer each time I play it. What to do here?

I really wish I could find a scan of the service manual for this as I've become accustomed to with audio stuff, but such is life. On the flip side, this is mostly working, whereas the cassette deck I was hoping to revive as well seems to have more major problems.

[n8nagel]

So when I play the tape to the end

in "normal" mode, it stops and rewinds.

in "real time" mode, it stops (display shows square "stop" icon)

Owner's manual oddly doesn't state what should happen at end of a tape, but these actions seem reasonable to me and actually kind of thoughtful - if you were using the real time counter and meant to rewind the tape, you might want to go to "normal" mode before doing so to save head/tape wear.

Apparently before, I must have come back in the room after the tape had passed the end of the recorded program, but before it actually reached the end of the physical tape, and the counter was in "real time" mode and not advancing, and that's what prompted that whole line of questioning. I did notice that the real time counter did not advance after the end of the program, but before the tape actually hit the end. So, mystery solved.

So, other than the noisy drum and the slipping idler, I think I'm good.

I'm pretty sure, having looked up pictures online, that the "Idler Assembly" PRB VA80 and/or replacement tire PRB ST1.205 are what I need. Any advice on removing? It looks like it just pulls straight up with a little plastic friction thingy but not having the manual I don't know.

Any idea on the noise? After picking the unit up and dropping it from about 1" while running (a time honored percussive repair technique) it's quiet again, but for how long?

[n8nagel]

I just went back and cleaned the tape path better (took the metal cover over the tape area off) and the roller and idler... maybe this is the key, I stopped at Value Village today and picked up a couple better looking tapes. It appears to be working correctly now! I also got the remote the other day and have it about 75% figured out. It can't really be duplicated with a universal however because you set the program with the remote and then transmit it to the unit, pretty cool. Although likely I won't be programming this to record any TV programs... Anyway I have a feeling this project is coming close to the end. Got a few evenings of cheap entertainment out of it.

One question: I picked up a copy of "The Dirty Dozen" that says "Dolby Surround" does that mean that if I play it through my AVR it will somehow detect that it is multichannel and decode it? Or would I have to manually set that mode, and what would I use? Thanks! (I seriously haven't regularly used a VCR since I lived with my parents, which I haven't done since 1992, and we only had it hooked to a stereo system not any kind of multichannel deal. No Laserdisc, no AC3, nothing like that.)

[Ed in Tx]

Originally Posted by n8nagel

One question: I picked up a copy of "The Dirty Dozen" that says "Dolby Surround" does that mean that if I play it through my AVR it will somehow detect that it is multichannel and decode it? Or would I have to manually set that mode, and what would I use? Thanks!

Dolby Surround is basically a 2-channel to surround matrix decoder and would need to be set on your receiver manually unless it defaults to that.

[n8nagel]

Originally Posted by Ed in Tx

Dolby Surround is basically a 2-channel to surround matrix decoder and would need to be set on your receiver manually unless it defaults to that.

Maybe I should take this over to QuadraphonicQuad as that sounds an awful like SQ or QS

[Ed in Tx]

Originally Posted by n8nagel

Maybe I should take this over to QuadraphonicQuad as that sounds an awful like SQ or QS

Be my guest. I've been on QQ since 2009. They will tell you the same thing. I've had a quad setup of some sort or another since 1973.

[Electronic M]

Dolby 5.1 matrixed into stereo for storage/transport is conceptually similar to the QS SQ and EV/Stereo-4 systems...So much so you can use a Dolby 5.1 reciever to dematrix SQ records.

How to properly activate and configure it varies from reciever to reciever, but as long as the VHS HiFi on the deck works and you get the reciever configured right it should work.

[n8nagel]

Originally Posted by Electronic M

Dolby 5.1 matrixed into stereo for storage/transport is conceptually similar to the QS SQ and EV/Stereo-4 systems...So much so you can use a Dolby 5.1 reciever to dematrix SQ records.

How to properly activate and configure it varies from reciever to reciever, but as long as the VHS HiFi on the deck works and you get the reciever configured right it should work.

I guess I'll have to do more research. Right now I'm stuck because I realize that neither my current receiver nor TV has an S-Video input! So I'm looking at S-Video to HDMI converters, but all I'm finding stretch the picture horizontally which I don't like, or do not specify, so I have questions out there.

One question, I just put the covers back on and moved this unit upstairs to the living room, even though I can't hook it up yet (unless I use a composite video connection) - I had it unplugged for maybe 10 minutes to straighten/neatly wrap the cord and put two covers on. Possibly unsurprisingly, the clock memory was not persistent even though it's been plugged in for several days. Does anyone know, so I don't have to purchase the repair manual for just this one item, where the clock/program battery or capacitor is located? Thanks!

Another thing I've noticed is that the factory remote won't play nice with NiMHs (it works, but the display is too dim to be readable) so I had to use my last two Energizer Lithiums for it. I won't use alkalines in anything anymore, too many failures.

[Electronic M]

Does your reciever have RCA analog audio input? If so that should be all it needs to decode Dolby 5.1....Theres no surround sound info in the video content.

If your TV has S-video input you can just connect video directly to the TV.

Clock settings rarely last more than 2 minutes on most decks even when new. When I'd go on vacation to the north woods for ~2 weeks at a time years ago I'd usually plug my decks into a UPS supply for computers to keep power outages from messing up timer recordings on the 3 decks I'd run.

[n8nagel]

Originally Posted by Electronic M

Does your reciever have RCA analog audio input? If so that should be all it needs to decode Dolby 5.1....Theres no surround sound info in the video content.

If your TV has S-video input you can just connect video directly to the TV.

Clock settings rarely last more than 2 minutes on most decks even when new. When I'd go on vacation to the north woods for ~2 weeks at a time years ago I'd usually plug my decks into a UPS supply for computers to keep power outages from messing up timer recordings on the 3 decks I'd run.

I don't have S-Video on anything. I must have had it on my old TV because I know I had a VCR hooked up before. But now I only have composite on receiver and composite and component on TV. HDMI on both, of course.

Edit: The owner's manual explicitly states "The timer unit of this VCR contains a memory protection circuit. In case of a power failure of less than approximately 24 hours, the display disappears, but the clock continues operation." etc. etc. etc. I can't post a link because I never found a scan of the manual, I ended up having to buy a hard copy (is there somewhere that I can post scans of it?)

Edit2: is servicemanuals.net legit? they offer a PDF scan of the service manual although not free. https://www.servicemanuals.net/en/NE...Service-Manual

Edit3: is there anywhere I can get a blank tape or two for a reasonable price, so I can finish testing the unit and remote functions? I've only found prerecorded tapes in thrift stores. I would also prefer to have at least one blank S-VHS tape so I could try recording in S-VHS mode and see if that works.

[n8nagel]

Just uploaded my in-progress file for the remote codes to the JP1 forums file section. It's good enough for just watching already although I haven't looked for discrete power codes yet if they even exist.

http://www.hifi-remote.com/forums/vi...c.php?t=103269

[Ed in Tx]

Originally Posted by n8nagel

I don't have S-Video on anything.

I wouldn't worry about that too much. Depending on the TV and the Y-C separator in it, composite video might actually look better than S-video. My old NEC CT-3000 30" TV looked sharper through the composite video. Go figure!

[n8nagel]

Coming back to this... I finally figured out how to get the copier at work to scan 11x17" sheets, so the owner's manual for this unit is now posted at ElektroTanya. I scanned it two ways, one with individual pages for reading online, and one that can be printed 11x17 to make a repro manual.