JVC HM-DH40000U D-Theater VCR in action (overview, quick repair tips, "hidden" DTS feature)

Had this open for a quick cleaning and thought, since the older chassis (the 30000U) generally gets all of the attention on here, that it'd be cool to hit record and go over the insides of this one, as well as look at how she operates. This one was given to me earlier in the year and was told she was in very rough shape--unit was definitely stored in an area with a lot of moisture. And yet, she refuses to die! Well, the VCR is very sensitive to drop-outs on the tape, but it's as good of a start as any.
Something not mentioned on the casing or even in the instructions manual, this chassis does indeed support DTS playback! On tapes that have DTS, it will appear as "STREAM". Even though the 'Audio Functions' menu allows you to set the default optical out as "STREAM", it still defaults to Dolby when the option is selected.

[@nihilyst]

Hello, great video. Nice to see some other D-VHS enthusiasts out there. I have worked a lot on these units the last two years and may have something else you might find interesting: the capacitors on the PRE/REC board very often tend to go bad. And they die slowly. In most cases, VHS/SVHS playback is not affected but the digital playback will deteriorate over time (show more and more dropouts). I had exactly the same sympthoms as your unit shows on one of mine. Some tapes play back well, some do not. I don't think the cassettes are necessarily the root cause for your drop outs. I think that some cassettes simply had a slightly weaker signal strength when they were produced. And these tend to highlight a recorders' weaknesses more. I replaced all the capacitors on the preamp board on a DH40000U, and now my DH40000 plays ALL cassettes I own almost 100% error-free. Also the previously faulty cassettes. In my opinion, the DH30000U (which is even older) may well have the same problem. Another problem is the ground connections from the preamplifier PCB to its metal housing. These break very easily and tend to tear the pad off the circuit board. Sometimes it is barely visible. You have to meticulously restore this connection, all three of them. I once had one that was broken and subsequently severe drop outs on all cassettes. From just a tiny crack in the solder. Of course I can't know 100%. Of course, it could be that your recorders are perfectly fine and they are really badly worn cassettes. But I was also able to see a few drop outs on the cassette that was declared good in your video and I actually had the experience that the devices, when 100% OK, actually only show very few drop outs. Regardless, it's great to see that others are also engaging with this obscure format. I myself have had a few problems finding repair tips for these devices on the internet. Nice that you share your experiences here. Since it is so difficult to get information, I am also sharing my experiences here. 🙂

[@VideoStore64]

Thanks for the comment! That is a good point to watch out of the ground connection on the shielding for the digital preamp board; on this one, I had noticed some cracks around the joint before working on it.

[@orihalcon8693]

Awesome video! Just restored a couple of these units - almost all of the SMT caps in the digital section were bad on both and neither really appeared particularly heavily used. They are kind of annoying to get to because the outer shielding is soldered on in many areas and there's about 25 of them. Guessing most of these DVHS machines have bad SMT caps that go unchecked. I think regular VHS playback also goes through the digital board as I think these will output an MPEG2 stream over firewire for regular VHS and they also have a line time base corrector which is ideal for VHS tape transfers and that would need to go through the digital section for that to function. Side note was that almost all of the push button switches on the front on both were also not making good contacts, so I would bet a fair amount of these machines could be listed for parts for non-responsive buttons - switch replace those is a 6x6mmx9.5mm 2 pin tactile switch.

[@VideoStore64]

Yeah, these units do get hot with all of the complex circuitry going on in the digital sections, as well as from the regular abuse switch mode power supplies put on caps, so the caps on these do dry up pretty easily. The digital board recapping is delicate work, but hey, you get D-Theater playback out of the deal. For the front-panel buttons, I'd apply Deoxit to them to see if they clean up before replacing them; they're likely just dirty from lying dormant for years.

[@TheMediaHoarder]

Such a shame these machines were so cheaply made, especially for how high they were priced. They should have been industrial-quality with linear stereo playback and overall best playback available for any VHS tapes. A few D-Theater tapes have DTS tracks but aren't mentioned anywhere on the cover, would be nice if you could set the default audio tracks to play back when available. I don't know what was different about DTS that the first players couldn't access it, there was a similar issue with the first-generation DVD players and DTS on DVD.

[@MrBushMan]

My dh40000u has screen flickering and I hear replacing the fan can fix this. Can you do a video on that

[@VideoStore64]

Does the fan spin up when the unit's turned on? As long as it does and there is no major dust accumulation on the inside, then the fan is fine. Do you have a description of what you mean by "screen flickering"? Can your unit do anything else? It's more than likely bad capacitors; those go bad easily on the D-Theater decks.