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  #1  
01-03-2013, 11:35 AM
LinParkFL LinParkFL is offline
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Trying to revive this unit which was sitting in my rack unused for quite some time. I've done some searches here and tried a few things but I'm basically stuck now. The player will power up just fine and stay that way as long as I don't try to put a tape into it. Once the tape is inserted (no matter what type - VHS/SVHS/DVHS), it seems to grab the tape, move it around the head for a few seconds, and then just shut down. I found a thread that spoke of small black gears under the head but this unit doesn't seem to have those. I'm able to put the unit into Jig RCU mode but I can't seem to find the IR codes for "59" so I can cycle through the EMG detail and troubleshoot further. I have a Philips Pronto remote that I could program if someone could get me a .ccf with the codes. The old PTU94023B remote seems to be unavailable these days. Can anyone assist?

Thanks!
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  #2  
01-03-2013, 01:57 PM
volksjager volksjager is offline
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that unit does not have a DD - so no little black gears, the problem is elsewhere.

does the video head spin up?
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  #3  
01-03-2013, 02:58 PM
LinParkFL LinParkFL is offline
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Yes, when I go to put a tape in the head starts spinning right away and spins the entire time until the shutdown.

EDIT: Not the best quality but I posted a video here of the process - > JVC HM-DH40000U Shutting Down Video

Last edited by LinParkFL; 01-03-2013 at 03:29 PM.
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  #4  
01-08-2013, 12:03 AM
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I bet I know what it is, you came to the right site. The issue is probably the same one that we had wrong on our 9800. I think kpmedia solved it. The head has a spin, and for some reason there's a little black "thing" on it that will get gummed up and not spin and will then shut down 3 seconds later. Take your finger, carefully go in there while its turned off and gently massage it a little bit and try again. This has been documented on this forum several times, search for it, it should be there.

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-JMP
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  #5  
01-08-2013, 07:35 AM
LinParkFL LinParkFL is offline
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Sorry, this unit doesn't have those little black gears. Does anyone have access to the JIG RCU? I'd be willing to rent one just to obtain the codes. I think if I can get to the emergency codes on the deck that I'll have a better shot at repairing this unit.
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  #6  
01-08-2013, 03:55 PM
volksjager volksjager is offline
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i have been trying to find a JIG RCU for awhile - they are practically unobtainable

check for bad caps - it may be a sensor problem to
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  #7  
01-08-2013, 10:08 PM
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We have a JIG here, but we can't sell it or send it out. If you want to send us the VCR down the road, we are willing to take a look at it, but we may or may not be able to fix it. I wish I had more for you, but unfortunately I don't. Maybe someone else on the forum will have more information for you.

What volksjager said is also great advice as well to check for.

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  #8  
01-09-2013, 08:15 AM
LinParkFL LinParkFL is offline
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Have you ever tried to capture codes from the JIG to another universal remote? All I need according to the service manual is code "59" to cycle through all the EMG information. If you could capture that and send it over to me I should be able to get a little further along in my analysis.

Where exactly are you located? I could then check on the cost to send you the unit and decide from there if it is worth it.

Thanks!
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  #9  
01-11-2013, 12:49 AM
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Realistically, it would be about a month before I could look at this. But we will try this for you if you can wait that long. It's a good idea and no problem.

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  #10  
02-14-2013, 01:28 PM
LinParkFL LinParkFL is offline
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Well, it's been a month - any chance you could help me out now?

Thanks,
Lin
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  #11  
02-18-2013, 08:55 PM
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Yes, we can. As I mentioned before you can send the unit to us and we can check it out with or JIG. Again, we may or may not be able to fix what is wrong with it. I will get with kpmedia to get you instructions on how and where to send it to us.

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  #12  
02-24-2013, 12:56 PM
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Contact Us if interested, and I'll handle it in email. (Then tickets in our helpdesk, if you do it.)
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  #13  
12-02-2013, 11:51 PM
ziggy90127 ziggy90127 is offline
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I went to use my HM-DH4000 the other day, and the clock "PM" indicator was flashing for a few seconds, and then not flashing for around a minute in a continuous cycle. It only seemed to obey inputs and remote commands while the PM was flashing. Even though it would ingest a tape, play, eject, etc. there was no picture or sound, and the menu wouldn't come up.

After much diagnosing, the AL4V (as specified in the jvc_hm-dh40000u_sm.pdf Service Manual) 4.4 volt power supply line was only outputting voltage varying from 2.0 to 2.6 volts, and it was dirty (sawtooth wave). I replaced some capacitors that failed the ESR test, and while I was then able to see a picture with herring bone patterns, there was still no sound or menu. The AL4V voltage was still dirty. I tried swapping and testing the through hole components of the section of the power supply responsible for AL4V, all tested good. That leaves the surface mount components… resistors, capacitors, and the MD1422N regulator chip. While testing, there was a buzzing noise coming from that area for between 15 - 60 seconds after power up, and then it went away, with a corresponding improvement in the dirtyness of AL4V. After some more playing around, the AL4V voltage went to 0, never to return.

As far as I can tell, the MD1422N (IC5401) DC-DC converter surface mount chip is bad. http://www.questcomp.com has that chip in stock for $4.50, but they want $50 for USPS shipping, or you provide your courier's account. ebay has listings for the chip, but they're in asia.

Not wanting to wait or pay large shipping fees, I decided to patch in an external power supply. To disable and isolate AL4V on the power supply board, I removed the CP5401 fuse, and the L5403 coil. I soldered wires to ground and AL4V, and ran them to an external 5V 2.5 Amp wall transformer. The transformer couldn't supply enough amperage. I then dusted off an old PC ATX power supply and hooked it up to the +5V line. Success! Seems to need at least 2.7 amps.

Well, almost success. No more flashing "PM", the menu comes up, sound works, and VHS tapes play great. But my DVHS tapes don't show a picture. It does seem to know if the material is SD or HD. On some tapes it comes up with "Wait a minute, Calibrating 201".

So, I've got it into a fairly good state, but I'd like to get the DVHS playback working. In reading some internet posts, others have complained that they got the 201 message simply by moving their deck from one room to another. In replacing 3 of the capacitors, I completely disassembled the unit, including removing the video head/drum assembly. So, is my 201 message because of my disassembly, or does the drum now need alignment even though it plays VHS just fine, or is it some other new problem I wasn't aware of? Would anyone even have the equipment, or know how to align this deck anymore? Probably would cost and arm and a leg. Not sure it would be worth it.

Why supply +5V to ALV4? MD1422N (IC5401) is setup to supply 4.4 volts. ALV4 only supplies the PQ5EV3 (IC5603) regulator, and that regulator accepts voltage up to 7 volts. The regulator will run hotter, however, and as there is already browning of the logic board in that area, it might be a problem in a closed case. So unless proven otherwise, treat this as a temporary test solution.

To test the ESR of capacitors in circuit, I used the advice here: http://fullnet.com/~tomg/esrscope.htm Based on my findings, I replaced the following capacitors: C5103, C5205, C5206, C5303, C5304, C5305, C5408, C5409, C5602, C5603, and C5604. The last 3 are on the main logic board, the rest are in the power supply. The power supply is fairly easy to work on after you remove the soldered on metal shield with solder wick. The capacitors are also easy to remove with solder wick.

If I had it to do over, you don't need to remove the tape mechanism from the main logic board in order to replace capacitors that I did, however, it would be hard to handle with the weight of the mechanism and the flexing of the logic board. In retrospect, I would have tried supplying +5V to ALV4 first to see if things worked, before replacing the 3 main board capacitors.

If I do end up getting the MD1422N chip, the easiest way to remove the old one is to use ChipQuik solder, it stays molten for a few seconds to allow the chip to be removed. Be careful though, the ChipQuik solder will splash and run around for a while after heat is removed, you don't want hidden solder bridges elsewhere on the board.

And for the requisite warning: I take no responsibility for damage caused to your equipment or you. Hazardous voltages exist. If in doubt, get a qualified person to do the work for you.

To create a power supply from a PC ATX power supply look here: http://web2.murraystate.edu/andy.batts/ps/powersupply.htm
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  #14  
12-03-2013, 10:03 AM
NJRoadfan NJRoadfan is offline
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On the DVHS tapes with no output, do you get any audio? If so, try an external Firewire decoder. A firewire compatible tuner like the Samsung SIR-T150 can do the job. Also, VLC Player on a PC with a firewire port can decode DVHS MPEG-2 Transport streams. I have a ton of DVHS tapes that were recorded on a Mitsubishi DVHS deck that simply won't decode using the JVC's internal decoder. I get audio, but no video on most tapes.

Regarding capacitors, with all the work to test ESR, just replace them anyway. Use high quality low-ESR parts from Japan like Panasonic. I wouldn't be too worried about parts from China. Others have used UTSource (the big vendor that pops up on ebay) without any problems. Quest Comp's shipping is a ripoff. I can see them wanting a minimum purchase quantity like Digikey does, but be up front about it!
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  #15  
12-03-2013, 12:55 PM
ziggy90127 ziggy90127 is offline
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Thanks for your firewire suggestion.

I hooked up my Motorola DCT-3416's firewire to the HM-HD40000's firewire, and I got HD just fine. I played a DVHS tape, but I get no audio or video, but it does seem to know if it's SD or HD material on the tape. I then fast forwarded to the end of the tape and attempted to record the firewire HD input. I don't get perfect playback, but I do get some! Yay! I get short segments with audio and video, and some freeze frames.

So I guess this means I need an alignment? I've never done that before, but the service manual does have a section on it, but it needs special tools, alignment tape, test jig, RCU etc. Do I have any hope of attempting it myself?
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  #16  
12-03-2013, 02:43 PM
NJRoadfan NJRoadfan is offline
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Auto tracking is a problem with DVHS tapes occasionally. For some of the tapes I got, I have to disable and re-enable auto tracking for the deck to "lock on" to the signal.
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  #17  
12-03-2013, 04:23 PM
ziggy90127 ziggy90127 is offline
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With VHS and S-VHS tapes, the tracking on/off and adjusting works. With my previously recorded DVHS tapes, there's no effect, I get no video or audio. With the brief 1 minute HD recording I just made on DVHS, in my first viewing I was just seeing a couple of slices of video with freezing. Now I see a more continuous video and audio, but with a lot of pixelation. Turning automatic tracking off and on doesn't change much, and manually adjusting the tracking doesn't bring the video/audio in at all.

I think what I'll do is properly fix the power supply, and have the local JVC shop do an alignment on it. They said $25 minimum, and if it's more than that they'll give an estimate, and they said they have the equipment to align it.

p.s. With my patch to feed +5V into the AL4V line, the PQ5EV3 (IC5603) regulator and heat sink get smokin' hot. I believe it went into thermal shutdown once. I've got a fan on it now, but even so it still gets very hot. So while +5V is ok for brief testing, it's definitely not a long term solution.
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  #18  
06-07-2017, 03:32 PM
oldsyd oldsyd is offline
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ziggy90127 did you ever revive your ailing JVC? I have the same symptoms in my Marantz MV8300 and I'm planning a full recap. I also was able to get a replacement MD1422N on Ebay for $3 including shipping from China.
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  #19  
06-07-2017, 03:55 PM
ziggy90127 ziggy90127 is offline
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Yes, I replaced the MD1422N, along with some capacitors, and it appears to be functioning fine. But I have not taken it in for an alignment, yet.... will I ever? Good luck with your fix!
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  #20  
06-07-2017, 04:18 PM
oldsyd oldsyd is offline
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That's great news! Why do you think it is out of alignment? Do you think the tape path is out of alignment or the head drum is out of alignment? I've always thought that if you don't remove those items and it was in alignment before then it should stay that way?
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