Quantcast Two Panasonic NV-W1 AG-W1 with same problem? - digitalFAQ Forum
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  #1  
06-08-2021, 08:30 AM
apfelmus apfelmus is offline
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Hi all,

I have two of these machines as my father in law is french and wanted to digitize its VHS (the small ones from his camcorder) that are recorded in Secam. The first one I bought worked well until after about 40 cassettes when it stopped shortly after pressing "play".

Some search revealed a video https://www.youtube.com/watch?v=HYvfoQnld18 where the exact same problem is adressed, traced down to the idler that lost friction. The guy swapped the idler with another idler from a G-chassis machine, stating that repair of the idler does not seem feasable.

As I did not have another machine to get the idler from I bought a second NV-W1. It worked all right at first, but after 3 cassettes it produced crackling sounds and there was a lot of smoke coming out of it... but when I reconnected the machine some minutes later it just continued to work as if nothing ever happened. Then it started the same behaviour as the other one, i.e. stopping after some seconds when in play mode!

The smoke and the idler problem seem unrelated, although I'm suspicious about this sort of coincidence. Is there a possibility to repair the idler? Can this mechanical problem originate in the electronics? Are these idlers a weak point of theses machines, and/or are there other weak points?

Any help welcome! I'm rather seasoned in troubleshooting electronics, but not so much VHS. I have the service manual... on opening the case I couldn't find any trace of heat or a damaged cap or anything. All voltages from the power supply are fine.

cheers
Martin
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  #2  
06-08-2021, 10:15 AM
latreche34 latreche34 is online now
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You are the only one that knows if it's possible to repair the VCR, We don't know your skills, we don't know the condition of the parts inside the VCR, Guessing posts are not going to help you. If you have repair skills take it a part and post pictures here or a video maybe we can help with the diagnosing.
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  #3  
06-08-2021, 12:51 PM
apfelmus apfelmus is offline
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Thanks for your reply. I have two issues:

(1) the electrical/electronical.
When repairing units from Tektronix or HP, more than once I encountered the line filter going up in smoke. Afterwards the unit continues to work. The line filter (the Shaffners) throw a lot of dirt all around them, so its easy to spot and repair.

Thinking of a similar problem in the VCR I opened up the power supply but could not find any traces in the section where the line voltage inputs the supply. Plus, the smell was stronger at another part of the VCR: atop the main board, where the sockets towards the input board are located. I dismantled the input board but all the components look fine. So I'm taken aback, and thats why I ask here, if maybe someone had a similar experience.

(2) the mechanical issue that both VCRs have, with the idler / clutch assembly.
What happens in my units is exactly what is shown in this video https://www.youtube.com/watch?v=HYvfoQnld18. The only thing I might do right now is unmount the clutch and examine it myself.
The G-mechanism can be found in many other VCR - I wonder if anybody knows if this idler/clutch assembly is a weak point in general, and how it could be remedied.

cheers
Martin
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  #4  
06-08-2021, 01:29 PM
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lordsmurf lordsmurf is offline
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Quote:
Originally Posted by latreche34 View Post
You are the only one that knows if it's possible to repair the VCR, We don't know your skills, we don't know the condition of the parts inside the VCR, Guessing posts are not going to help you. If you have repair skills take it a part and post pictures here or a video maybe we can help with the diagnosing.
A bit harsh, but accurate.

Quote:
Originally Posted by apfelmus View Post
I'm rather seasoned in troubleshooting electronics, but not so much VHS. I have the service manual... on opening the case I couldn't find any trace of heat or a damaged cap or anything. All voltages from the power supply are fine.
To some degree, it's all about the electronics anyway. VCR repair is more focusing on engineering, electronics, less on video theory. I've long said that those who fix or design VCRs, and users of VCRs, are separate, different skills. Some overlap with more seasoned users, but still mostly separate, you fork one way or the other on the skills.

- Did my advice help you? Then become a Premium Member and support this site.
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  #5  
06-08-2021, 11:35 PM
apfelmus apfelmus is offline
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Quote:
Originally Posted by lordsmurf View Post
To some degree, it's all about the electronics anyway...
To some degree, yes. But if I do not have enough tension on the band after the capstan, i.e. the takeup reel has not enough couple and even stops, thats much more mechanic. Thats what I meant with "I'm not in VHS".

When searching the internet I learned that many VCRs share the same mechanism, in this case the "G"-machanism from Panasonic. So I hoped that there may be some knowledge about this type of problem, apparently caused by the idler/clutch assembly.

I'm currently opening and studying the C-Type Adapter that I'm using, if it has a problem somewhere. On the other hand, in my AG7630 the cassettes play fine, albeit in black&white.

cheers
Martin
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  #6  
06-09-2021, 11:25 AM
apfelmus apfelmus is offline
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Hi all,

today I checked the idler/clutch assembly - it looks fine, and has good torque. See the pics, thats the one that has been swapped in the video I mentioned in my earlier posts. I put everything together again, and this time it seemed to work OK, so far. The one that went up in smoke, that is...

The other VCR still refuses to play, so I made a cheater-cassette to have a closer look. In play mode it indeed has very low couple on the takeup-reel. There are 2 brake pads on the reel (see last pic), one of them is engaged in play mode. When, during play, I lift the brake pad off the reel it it starts having good torque, so it seems the brake pad eat up most of the couple coming from the mechanics. It even stops sometimes.

Is it normal the brake is engaged in play mode? When the brake pads wear out, is it possible their brake action gets stronger instead of weaker? They do not seem to be adjustable, the brake action is governed by a simple spring.

cheers
Martin


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  #7  
06-09-2021, 11:09 PM
latreche34 latreche34 is online now
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No, the brake pad should lift off during playback, It is either broken, disconnected or you have mechanical timing issue. Check the service manual and study the operation sequence of the mechanism, do a manual sweep of all modes by turning the drive motor by hand and observe the operation.
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  #8  
06-09-2021, 11:53 PM
apfelmus apfelmus is offline
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Thanks for the Info about the brake. I checked the mechanics - so far I can exclude a broken or disconnected link, but I will check if its identical in the other machine.

How do I make a "manual sweep"? To change mode I have to select the mode (FF, FR, play, stop) on the front panel, but then the motor will start and do all the work.

I might initiate the change through the front panel and then cut electricity and do the rest by hand - would that be equivalent, mechanical-wise?

cheers
Martin
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  #9  
06-10-2021, 06:14 AM
apfelmus apfelmus is offline
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I checked the second machine, and the behaviour of the brake pad is identical.

Are you sure that is not normal? In the service manual I could not find a single word about these brake pads and how they work or should be maintained. There are some videos on the web about strip down and alignment, but there also is no mention of the brakes.

cheers
Martin
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  #10  
06-10-2021, 01:35 PM
latreche34 latreche34 is online now
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The manual sweep is done with the power off, The VCR will go through all the modes except that the head drum and capstan motor will not be operational. To understand this you will have to know how a VCR works, Take some time time and read some technical guides.
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  #11  
06-10-2021, 03:03 PM
apfelmus apfelmus is offline
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Quote:
Originally Posted by latreche34 View Post
The manual sweep is done with the power off. The VCR will go through all the modes except that the head drum and capstan motor will not be operational.
With the cassette loaded, or unloaded? When unloaded, I can turn the capstan drive wheel in one or the other direction, but it will block after some turns. There seems to be some other action required...

Quote:
Originally Posted by latreche34 View Post
....Take some time time and read some technical guides.
Can you provide some links?
I did a lot of research these days, the best thing I came across was https://www.repairfaq.org/sam/vcrfaq.htm, but that does not help for manual sweeping or how the brake pads are supposed to work.
Do you know of a more detailed service manual for another VCR that uses the G-chassis?
My version is from www.freeservicemanuals.info, it has 143 pages including circuit diagrams on component level.

cheers
Martin
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  #12  
06-10-2021, 03:22 PM
latreche34 latreche34 is online now
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Start off with the service manual of your model or similar mechanism model.
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  #13  
06-10-2021, 05:40 PM
hodgey hodgey is offline
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You can find one manual for the G mechanism here. (Seems to be missing some pages)
There is also a manual for the last revision of it here which optionally had an extra motor to help with seeking used in the later high-end decks. I'm not sure which one is closer to the one in the W1, but the parts are mostly the same.


This video of a slightly older revision of it may also be helpful and illustrates how to turn it manually.Everything is driven by the capstan motor, and there is a solenoid that switches a thing that makes turn the mechanism gears.
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  #14  
06-10-2021, 07:59 PM
Dougmc Dougmc is offline
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I remember some of those soft brakes had
Felt type material.
Maybe the soft part is worn as in picture can see debre

Under it and the base of the felt is grabbing
To much.
Maybe try getting some felt from a fabric place.
I assume the brake assembly is nla.
It's been a,while since I services these.
I was very active in the 80s 90s in vcr service
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  #15  
06-11-2021, 02:33 AM
apfelmus apfelmus is offline
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Quote:
Originally Posted by Dougmc View Post
I remember some of those soft brakes had Felt type material. Maybe the soft part is worn as in picture can see debris...
Yes, I noticed that, too. The pad is probably a felt-like material, but there is a thin coating of a leathery plastic of some sort that actually makes contact with the reel (and who's debris you see on the pic).

Quote:
Originally Posted by Dougmc View Post
I assume the brake assembly is nla.
What is "nla"?

Thanks to "hodgey" for the links. I tried the manual operation in the video, can't find anything wrong with the brake pad movement. All the service documents share the same content, and do not mention the brakes (and their intended movements) at all. So for now I reckon the brake movement is OK, but the brake pad has increased friction to a point where the takeup-reel does not have enough torque anymore.

Fortunately I have a 3rd G-chassis, from a bargain-W1 who's front panel was damaged beyond repair. The brake pads of this chassis seem clean, no debris. I'll swap them, and will report back...

cheers
Martin
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  #16  
06-11-2021, 02:43 AM
latreche34 latreche34 is online now
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What brake pads have to do with playback? In playback it should be no brakes at all regardless if there is a felt pad or not. Worn brakes when fast forwarding or rewinding cause a tape spill due to the inertia of the hubs, if you eject the tape it will get caught by the mechanism.
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  #17  
06-11-2021, 03:48 AM
apfelmus apfelmus is offline
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Quote:
Originally Posted by latreche34 View Post
What brake pads have to do with playback?...
Don't ask me... ;-)

I have the information I mentioned in my other posts. Nothing specific about the brake pads and when they should be on and when not. If you have any document that may provide further help you're welcome to share it.

Up to now all I have is my mechanisms that I can watch. Since both VCRs behave exactly the same, chances are that this behaviour is nominal.

cheers
Martin
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  #18  
06-11-2021, 01:24 PM
latreche34 latreche34 is online now
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Post #13 has the links you need.
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  #19  
06-12-2021, 02:35 AM
apfelmus apfelmus is offline
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Quote:
Originally Posted by latreche34 View Post
Post #13 has the links you need.
In my post #14 I explained that these links do not tell anything about the brake pads and their intended behaviour.

You say that the brakes must be off - but how do you know this applies for the "G"-machanism? If these brake-pads in two VCR with the "G"-mechanism, my NV-W1's, behave exactly the same, one would assume this is intended behaviour.

cheers
Martin
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  #20  
06-12-2021, 01:37 PM
latreche34 latreche34 is online now
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Brakes has nothing to do with playback for any VCR, Camcorder, DAT machine, Data storage drive....etc. That's just how physics work. Motors are go machines, Brakes are stop machines. Have you ever driven your car with both brake paddle and gas paddle pushed down, Try it and see what's going to happen.

Besides the gap is too small to notice if the brakes are applied or released, It's like half a millimetre, Put the vcr in playback and remove the power, insert a sheet of paper between the brake pad and the take up spindle, if the paper goes through it's good if it doesn't you got a problem.
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