Panasonic NV-3120 VTR - Videokarma.org TV - Video

EdKozk2 · #1 06-19-2016, 11:13 PM

Hi,
My son and I found this Panasonic NV-3120 video tape recorder and over 75 tapes at a storage locker sale this past weekend. I figured it might be repairable since it is all transistor, no analog chips. I plugged it in, using a modern 3 prong computer cord. The pilot light works, the transformer hums, but the motor doesn't turn.
The fuse is OK. I think this would be a really cool VTR to get working again.
Has anyone ever worked on one of these? I also could hear a relay when power is first turned on.
I would like to get hold of a schematic for this, it would make repairing it so much more easier.
The Labguy website for old video equipment shows a service manual for sale, but the website won,t link to a payment service. Is he no longer selling the schematics ?
ED

EdKozk2 · #2 07-05-2016, 11:37 PM

Hi,
I bought the service manual for this Panasonic NV-3120 from Labguy, Rich Diehl last week. I had to reach him via email. As soon as I looked at the schematic I discovered there was a tension switch in series with the motor switches. A tape has to be installed, in order for the VTR motor to spin. I cleaned up the video head a little and demaged the audio head. I tested some of the old tapes and found that only some would pass over the video head without sticking / binding. The Scotch and Maxell brand R2R videotape slide over the head trouble free.
The Sony and Memorex brand tapes get stuck. It's like they are maganetized.
They even start to stretch. The tape that does work, seems to be made of a different base stock, similar to standard R2R audio tape.
Has anyone ever had or used a VTR like this? Were these early VTR's brand specific when it came to blank R2R videotape? This Panasonic is helical scan.
The audio has some intermittent hum and feedback. The video has color and sync issues I have yet to work on. Many of the image quality issues seem to be related to age of videotape. The newer the recording the better the quality.
Pictures below are some of the first tapes I viewed. This VTR has a channel 5 or 6 RF modulator. I get a better signal on channel 5.
My son and I tried recording and got about the same quality image as the old recordings. We used an old tape to record over.
ED

jsowers · #3 07-06-2016, 03:06 PM

Reel-to-reel tape from the late 1970s sometimes suffered from lubrication problems and some of the cheaper lines of tape were literally unplayable after a few years. I'm only familiar with this happening with audio tape, but I suppose the same could happen with video. Storage in high temperature locations could also degrade the tape. Those tapes that are getting stuck probably lack lubrication, and the oxide can come off on the heads and gunk things up.

What you can try to do is fast forward and then rewind the tapes before playing, to see if they travel OK and don't gum up the works before you play them. When you clean the tape transport area, clean everywhere the tape touches.

I used a deck like this in high school. They could only afford a black and white camera, which I thought was so dumb. The only way (at the time) to record TV shows on this VTR was to use an external tuner in a TV monitor that has an 8-pin plug and an 8-pin cable to connect the two. Not an easy thing to find.

MIPS · #4 07-06-2016, 05:54 PM

Wouldn't baking the tapes like reel-to reel audio tapes work in this case?
I do find it somewhat humorous that someone recorded episodes of Connections.

EdKozk2 · #5 07-06-2016, 11:51 PM

I've had audio reel to reel tape where the oxide just flake off, the old junk brands of the 60's and 70's. It can get into everything. On the this VTR , everywhere the tape travels is clean. Tomorror I'll try and post some pictures of the two types of tape. The old video recordings were stored in seal plastic bins in a storage locker. Alot of the old recordings were PBS shows and movies from the late 70's, early 80's.

Telecolor 3007 · #6 07-07-2016, 04:23 AM

That blue stripe that you see on the screen is because of the machine or because of the tape?
Sheesh, I thought in the past in Capitalist where better tapes and the bad tapes camed only in the '80's, with the rise of other Asian countries (besides Japan).

Electronic M · #7 07-07-2016, 08:47 PM

The tapes do need to be baked (140 degrees f IIRC) based on what I've read on EIAJ VTRs/tapes.
I have a working SONY AV-5000A and a working IIRC Concord monochrome deck....But, I've only got two tapes and would love to buy some off of you. I've also been looking to get an EIAJ standard color VTR...If you want to trade for a working Zenith VHS long-ways-loader (and or other stuff), or sell the whole thing, let me know.

EdKozk2 · #8 07-07-2016, 10:37 PM

Quote:

Originally Posted by Telecolor 3007

That blue stripe that you see on the screen is because of the machine or because of the tape?
Sheesh, I thought in the past in Capitalist where better tapes and the bad tapes camed only in the '80's, with the rise of other Asian countries (besides Japan).

I think the blue stripe/ static in the pictures is most likely due to the tape. I have yet to check if the motor speed or electronic troubles are also contributing to the crummy images. Some of the newer recordings had less interference.
In the pictures below the brownish recording tape travels throughout the VTR with no problem. The dark black tape just locks up, won't travel at all, over the video head.
I did a test with modern vhs video tape and it also locks up/ seizes when passing over video head.
There may be a slight height difference in the tape brands for all I know.

EdKozk2 · #9 07-12-2016, 03:47 PM

Quote:

Originally Posted by Electronic M

The tapes do need to be baked (140 degrees f IIRC) based on what I've read on EIAJ VTRs/tapes.
I have a working SONY AV-5000A and a working IIRC Concord monochrome deck....But, I've only got two tapes and would love to buy some off of you. I've also been looking to get an EIAJ standard color VTR...If you want to trade for a working Zenith VHS long-ways-loader (and or other stuff), or sell the whole thing, let me know.

Hi Tom,
The tapes and VTR belong to my son. I'll try and bring some along to the Milwaukee WARCI meet on the 17th. Maybe you can bring your Concord B&W VTR. That way I can check for tape bind over the head. From what I,ve read Concord and Panasonic were the same. I'll try and bring both types of tape.
Ed

Electronic M · #10 07-14-2016, 08:03 PM

Quote:

Originally Posted by EdKozk2

Hi Tom,
The tapes and VTR belong to my son. I'll try and bring some along to the Milwaukee WARCI meet on the 17th. Maybe you can bring your Concord B&W VTR. That way I can check for tape bind over the head. From what I,ve read Concord and Panasonic were the same. I'll try and bring both types of tape.
Ed

I PM'd ya 'bout it.

I'm pretty sure the sticky tapes will always bind on all decks until they get baked out....I had a sticky Sony tape that bound on both my decks.

What causes the binding is the glue used to hold the magnetic powder to the plastic tape...Some formulations overtime absorb moisture and become sticky. The key to making them stop binding is to dry heat them to 140 degrees F for a few hours (audiophiles have good info on this issue posted online since some multitrack studio audio decks used the same tape stock) and let the moisture bake out, then keep them sealed when not being played/recorded. Keeping desiccant (such as those silica pouches that come with new shoes) in with the tapes will help prevent recurrence of binding after they have been baked.

EdKozk2 · #11 07-15-2016, 12:08 PM

I'll have to give tape baking a try.

centralradio · #12 07-17-2016, 01:26 AM

Classic machines.Watch many videos in school on these.I have the NV 3160,NV3020 and Sony here.I used to use it before I got VHS.Yes the tape binding was a PITA.I'm glad that yours is running.

digicube · #13 07-04-2019, 01:14 PM

Did you manage to get the machine fixed? Are SONY tapes recorded on SONY machines playable on this Panasonic machine?

digicube · #14 07-14-2019, 04:08 PM

Can you post a download link for the manual? Is the video output using a BNC connector?

Electronic M · #15 07-14-2019, 05:01 PM

Quote:

Originally Posted by digicube

Can you post a download link for the manual? Is the video output using a BNC connector?

All EIAJ decks I've seen as well as early U-matic from that era used PL-259 (aka UHF connectors) for video with RCA or 1/8" mono head phone jacks (or possibly some other connector) for audio, and 8 pin EIAJ A/V connectors...If there was an onboard RF modulator it would either be PL-259 or F type.