Well said, zxck.
+ Reply to Thread
Results 61 to 90 of 92
-
The real cost of such device will far exceed the $300 mark if he accounts his developement time and set a target of early adopters to say 100, We already know he is not making a lot here if any, I get the sense that he is doing it for fun and for the community of hobbyists. If you hire a company to do this for you from A to Z with only one final prototype they would charge you anywhere between $50k to $150k and you will have to market it yourself.
I don't think Aramkolt meant expensive in the sense that he can't afford it, I think he means he has no need for it since he has modified many VCRs without such board, If he is doing the repair for someone he makes sure to make some profit as well, maybe with $100 board he won't be able to make that profit, And I agree there are cheap skates out there, there is no doubt about that. -
I hate how this forum doesn't have multi-quote.
@zxck
I want one, but I'll let dellsam34 be the guinea pig. I can wait. If it sells out, then so be it. MS has also robbed me of my fine dexterity, and it can be painful to force muscles/nerves to cooperate. I want some reassurance that I won't put myself through that for nothing. I have plenty of decks, and I've operated without my 9800 for years now. I mostly keep it for nostalgia, and the hope that it can be revived.
Also, very well said, your "the funny" speech in post #60.
To go one further, I had to roll my eyes at vhs-decode's Harry, who's first question was "can I download it for free at Github". No, you cheap mf'er, some people would like to enjoy the fruits of their labor.
@dellsam34
Correct, I did not refer to a $100 3D printed cage. That would be silly.
@aramkolt
I enjoy seeing your enthusiasm for these video communities, but I sometimes fear you'll burn yourself out, and move too quickly at times. Pace yourself. Be master of some, not "jack of all decks" (master of none). Focus on AG-1980P for sure, and a few others. I've seen too many VCR repair guys get burnout, including all the names you know (and some that quit).
@hkorpim
Contrary to some comments here, it would be a shame to fix these VCRs, then have the units immediately eat tapes (or fail in other ways). Most users are not as savvy as the few in this conversation now, and would have blamed you for a bad chip. But we've moved past that now, just replace the PDF instructions to showcase zip ties.
You've done a great thing here, and I await dellsam34's feedback.Want my help? Ask here! (not via PM!)
FAQs: Best Blank Discs • Best TBCs • Best VCRs for capture • Restore VHS -
Has anyone ever accurately measured or scanned the original gears of the Dynamic Drum System and tried to reproduce them on a 3D printer?
Are there any 3D files of the gears available? If not, I'm thinking of contacting a company that provides professional 3D scanning and printing of spare parts and try to reproduce them. Isn't accurately reproducing the gears the best way to rebuild the DD system rather than trying to trick it and bypass it by other means? -
There is a chap on eBay who 3D print the upper gears and selling them for $350 a set, just to make the mechanical bypass work as outlined in this thread's original post, The small gears with metal core are not easy to reproduce with a FDM printer due to the brittlness of the plastic when put over the metal shaft. A company may charge you an arm and leg for that but you can give it a shot, I'm not too optimistic about the whole 3D print concept, it may not last as long as the original gears.
We should be gratfull for this DD emulator that came to reality, We've been dreaming about it for years, So far it is the best fix. -
-
Yes i'm aware of that seller on ebay. I assume he's selling the complete service of the machine and not just the gears. You have to send him your device and he fixes it.
His listing says "Expert Service - JVC VCR VHS Dynamic Drum Disabling Service **3D Printed Gears**"
Do you still have the 3D files and would you be kind enough to share them with me?Last edited by Aristarhos; 3rd Feb 2025 at 05:49.
-
-
Last edited by Aristarhos; 3rd Feb 2025 at 12:16.
-
A 3D printer cannot make gears that will last, the material is too brittle for these fine moving parts. That eBay guy is delusional, it's a pure money grab. Whatever he does will break sooner than later. dellsam34 and I have discussed 3D printers for years, and those were always dismissed.
The mods discussed here are final, no more screwing around with it. That's what we all want.Last edited by lordsmurf; 3rd Feb 2025 at 10:34.
Want my help? Ask here! (not via PM!)
FAQs: Best Blank Discs • Best TBCs • Best VCRs for capture • Restore VHS -
-
In my long message yesterday, I said, that 'DD emulator' could be mounted directly to main board socket CN3501. I made rough feasibility study of available space and it looks OK. This applies to my HR-S9700, but I think (?) other models don't differ much on that location. The current pin header in 'DD emulator' is 6 pins / 2.54mm pitch. CN3501 requires 6 pins / 2.00mm pitch. On next revision of PCB I will add this direct mounting option. I also need to reverse order of terminals REV/FWD/SW5V/GND/MFG/ABS. For direct mounting ribbon cable is no longer needed. See below foto of 'DD emulator' placement under video head drum. Disadvantage of this mounting option is, that it will occupy the space of DD gearbox.
For next revision of PCB I will also revise the technical installation document with proper advice for fixing e.g. with zip ties.
[Attachment 85283 - Click to enlarge]
First 'DD emulator' to U.S. was posted today to dellsam34. Transportation will take 4... 7 days.
Alex9876 asked today how to adjust the mechanism after replacing the gears (or after disassembly...). I have one hint, which is shown in picture below. The 2 outer gear don't seem to serve any purpose, but they are actually thubwheels for adjustment. First screw the screwgear into video head drum, but not so tight, that either of the screws starts to tilt the drum - Leave some clearance for adjustment in next step. Secondly mount the gearbox to video head drum with 3 screws, but without SENSOR PCB and without the worm gear axle. Play a tape and when playing tape, if the picture is misaligned or scrambled, turn from one of the thumb screws (that rotates the gear screw) trying to find good picture = neutral position of video drum. If one thumb screw doesn't find alignment/good picture, turn the other one opposite side. After alignment is OK, adjust the other thumbscrew so, that it will just touch the drum with zero clearance, but not forcing it. After done, screw off video head drum, snap the worm axle in, clip on sensor PCB, solder motor wires and screw it back to deck.
For this method there is only one problem: the VCR shuts off after 3 seconds. You can only make this setting with DD emulator connected on a running VCR.
If you don't have ways to prevent shut off, you can try with trial and error: very gently manually screw the gear screws in, for zero or very very small clearance without forcing any tilt. Adjust DD gearbox gear alignment as described in my technical document "JVC Dynamic Drum gearbox" features and settings", that can be found from this thread. After that mount the DD gearbox fully assembled including sensor PCB to deck. With some luck, it should work properly.
[Attachment 85284 - Click to enlarge] -
Thank you hkorpim for the detailed description of the drum adjustment technique.
I will definitely try it.
I think the described technique will be interesting to many here. -
That's an excelent procedure.
-
One more thing to supplement my previous message regarding the drum alignment adjustment: Do not rotate the 'thumbwheels' when the gearbox is removed. They have friction contact to adjusts the tape path, so only rotate them after the screw gears are set correctly and the gears and gearbox are mounted. If picture is perfect, better not to touch any of these 4 gears and if you need to remove the gear screws, record their position i.e. how many turns out, when screwing them off. If you remove the thumbscrews, just pull them off without rotating them.
-
Hmm. If the fine tooth gears don't serve a purpose beyond initial alignment, this should be the easiest functional fix using (not super hot) hot glue:
Apply a small amount of hot glue to keep the gears in their exact position on either side (so that they don't move at all when the DD unit is removed from the bottom of the drum), detach the DD unit and remove both fine tooth gears, reassemble, then pull off the hot glue. This way factory alignment preserved, and no cracked fine tooth alignment gears to jam up the mechanism.
I'd try this method myself, but all of my DD VCRs have been bypassed. To really do it correctly, you'd need a VCR that hasn't had the DD unit off of the drum yet to make sure the factory alignment hasn't moved.
This will not prevent the transverse gear that is directly driven from the center of the shaft by the motor from cracking, which does happen sometimes. I'm not sure if those tend to crack because the fine tooth "alignment" gear jams *FIRST*, or if it's just the stress of moving the drum around. My guess is it's the cracked fine tooth alignment gear freezing the mechanism that causes it though.
I still think the usual bypass is fine, but the relatively noise-free FF/REW is a cool trick when it does work. Not really required for transfers, but cool nonetheless, and I'd preserve it if it was as easy as the "hot glue" method detailed above.
The hot glue might not even be needed the more I think about it, but I'd probably try it that way first out of caution if there's any chance at it preventing the need for a manual realignment.Last edited by aramkolt; 3rd Feb 2025 at 21:18.
-
Yes, hot glue, what do you think hkorpim, dellsam34?
Want my help? Ask here! (not via PM!)
FAQs: Best Blank Discs • Best TBCs • Best VCRs for capture • Restore VHS -
I decided to share with you the story of how I restored the Dynamic Drum mechanism. Please be lenient with my methods, I must admit I am not a mechanic. But this is my first attempt. Here is the link to the file.
https://docs.google.com/document/d/1oTRx1onKzR8mEepGSTyVwVkw9LwGxveJX_0tAwIrwRo/edit?usp=sharing -
-
-
Edit:
After going over my original post I can see one potential way of re-aligning the gear box: Put the drum back on the chassis with just the 4 gears with metal core, Back off the two thrust screw gears until they are free, One screw moves up the drum, the other moves up the lead ring. Screw in one at a time until it touches the base without applying a load and stop (zero play, zero load). Both the drum and lead ring should be touching the thrust screw gears with no load at their neutral position.
Here is how I think the system works, In the neutral position both the drum and lead ring are perfectly mated, the screw gears are touching them but no load yet. When the motor spins, one screw gear starts to push the drum up (not sure wich side), the drum pushes down the lead ring on the opposite side of the pivot legs, the other screw has to move down of the same amount allowing the lead ring to go down, this creates a tilt of the entire head assembly in one direction. In reverse, the opposite screw gear pushes the lead ring up, the lead ring pushes the drum up with it, which makes the drum go down on the opposte side of the pivot legs, pushing the lead ring down with it and the screw gear on this side will be moving down with the same amount allowing the assembly to tilt in the opposite direction.
I hope I'm not wrong, if I'm I would like to see a better explanation.Last edited by dellsam34; 4th Feb 2025 at 03:59.
-
-
Thank you, Alex9876, for excellent document re gear fix and well thought out method!
Regrading to question about small drop of hot glue, I believe, it works for holding the gear temporarily, because it's not sticky and comes off easily in one piece after.
Myself, I have never disassembled the head drum further - not removed the spring loaded screws. After the gearbox has been removed, the drum rests stable on resting nipples as dellsam34 states. I think, it is essential to keep the tension of the 2 spring loaded screws in factory settings, in order to prevent overload to gears. But when using the VCR without DD gearbox, I needed to tighten the screws 90 degrees (1/4 turn). This made the drum sit tighter and better aligned. If mounting back the DD gearbox, remember to loosen the screws back 1/4 turn. -
Yes, I believe I mentioned that in the disabling procedure in the main topic, It feels weak with the gears out, So giving it more spring tension makes it more sturdy withstanding tape tension around it. And yes it the gears are to go back, spring tension must be restored to orginal value.
-
In case anyone is interested, from the Service Manual this is the prosedure to preset the dynamic drum.
Needed equipment are an Oscilloscope, an Alignment tape [MHPE-L] with Stairstep signal (color bars?), a preseting remote control unit [PTU94008] wich apparently is impossible to find. Measurement on test points: point •TP106 (PB FM) and Trigger slope (+) •TP111 (DRUM FF)
"Connect the oscilloscope to TP106(PB FM/COL) of the main board assembly and to TP11(KD.FF) of the main board assembly for external sync connection."
From the manual of the PTU94008 pressing keys M+D or M+E triggers the Dynamic Drum or the Head Switch point.
Maybe pressing keys M+D control the motor of the DD gears and tilts the head to adjust the initial position. -
But what if the gears are mechanically mis aligned? like one screw is sticking further out than the other. But thanks for sharing this.
-
If one gear is misaligned related to others, run DD gearbox outside the deck using extension leads from CN3501 (or with DD emulator connected, if DD gearbox is jamming). First place the "thumb gears" only. Tape outgoing side is more critical for misalignment and it is accessible, when VCR is running. Supply side is difficult, because it is hiding under deck. Rotate the thumb gear using thin screw driver. A very small movement can make big difference in picture on PLAY mode. Use a tape with LP or EP speed recording. If tape alignment is OK (=perfect picture on PLAY), never rotate thumb screws by hand. Finally mount the gear screws as described on previous messages.
-
I was replying to Aristarhos who suggested remote software alignement, I was basically saying what if the gears are mechanically mis aligned would the remote procedure still works?
-
I've looked at the Service Manuals of S9500, S8600, S9600, S9800 and there is no reference to the screw gears or any DD gear for the DD preset procedure.
I have examined three JVCs HR-S9500 with DD system and a PHILIPS VR1500, wich is a JVC clone with Dynamic Drum, and they all had the split thumb gear, the upper gear as you look above the drum. I suspect that these small gears are the most fragile and the first candidates to break and block the mechanism. PHILIPS VR1500 was beeing tested by me and everything was working fine for 15 minutes until i tried the freeze frame and slow motion back and forth and it litteraly died in my armsIt was shutting down in 3 seconds. I took a closer look under the Drum and saw the split thumb gear.
Now i am wondering if this small thin gear splits first leading to the jamming of the rest of the DD gears that stress and crack.
And if it is possible to re-enforce those small gears before they break or even 3D Print them but thicker with longer teeth that would make them sturdier.Last edited by Aristarhos; 5th Feb 2025 at 06:05.
-
I believe so too, One or two gears take out the rest due to the high torque of the low gear ratio.
Similar Threads
-
JVC Dynamic Drum "Workaround"
By ybarra in forum Capturing and VCRReplies: 5Last Post: 27th Nov 2020, 19:22 -
Installed new CP4001 fuse and now video drum will not stop spinning.
By digicube in forum Capturing and VCRReplies: 17Last Post: 13th Jun 2017, 14:00 -
Pads under a tripod to prevent "kick drum" vibrations
By Robin13 in forum Newbie / General discussionsReplies: 5Last Post: 10th Mar 2017, 20:12 -
8mm tapes grinding video drum of DCR-TRV740
By digicube in forum Camcorders (DV/HDV/AVCHD/HD)Replies: 2Last Post: 5th Jan 2017, 11:22 -
JVC: do I need a Dynamic Drum for VHS tapes recorded w 80/90's camcorders?
By LouGee in forum Video ConversionReplies: 13Last Post: 10th May 2016, 09:40