JVC HM-DH30000U power problems?

[jaffa225man]

Quote:

Originally Posted by Blatte

Hey guys,
In my case, after having checked every caps on the power supply PCB , I changed these (got from mouser.com):

33pF, 1kV
C5103

100uF, 10V
C5310
C5312
C5314
C5316
C5318
C5320

4,7uF, 100V
C5208

18uF, 50V
C5209

470uF, 10V
C5301

330uF, 10V
C5303

Now, the VCR turns on well.
Input/output video and audio signal on TV OK
VHS playback, audio/video perfect
DVHS playback, video perfect, audio very low
No digital audio signal (the fiber is red lightened) either.
The problem comes from the Digital PCB. I switched with the one from my other (working) 30000U deck and it worked fine.
The problem with the Digital PCB, it's "digital very small" electronic. I don't have the tools and (first of all) the knowledge to fix that kind of stuff.
If anyone has some good tips, that would be cool

I'd like to add this visibly exploded and rattling empty can of a capacitor in my power supply to your excellent list. While it was truly that bad and causing an intermittent display, it still measures as 1 Ohm ESR even after removal:

4700uF, 6.3V
C5203

I know it's probably not that much help this much later, but I did replace all the capacitors on my digital PCB, even before finding your post. This is my rarely-practiced method for removing SMD caps (hopefully without tearing pads, but that can happen during removal and bodge wires may be needed to rebuild connections that break). It's not for the the faint of heart, but it can be successful with perseverance. Take these words with caution, because I won't be held responsible for mistakes made attempting it. As always, it's best to first attempt it on a PCB that's scrap anyway:

Using a very small soldering iron tip, I heat up the positive side of the cap until it begins to melt. Then I tilt the capacitor can up from that positive side by gripping it on top with my tweezers until its solder blob is no longer making contact with the pad, while leaving the negative leg to bend upward a bit, but staying connected. Next, I move on to heating just that negative side and when it's melted, pull the capacitor up off the board with the tweezers.

Finally, using the tweezers and/or a needle-nose pliers, I bend a new replacement through-hole capacitor's legs to either right-angle the capacitor in a very low-rise area of the PCB, or right-angle the legs flat out on one side from under its can to let it stand just beside the traces it'll be soldered to, leaving the capacitor upright, in areas of the board where high capacitor density makes laying them sideways impossible.

I choose to use new through-holes mainly because they have better temperature ratings for longevity. I also don't like how SMD caps obscure all but a very tiny portion of its pads, and the minimal direct soldering iron access to them when soldering new SMD caps back on.

Good luck in any endeavors!

[aramkolt]

Since this thread was brought back, I'd comment that I still haven't had good luck with this series of D-VHS machines - can't say on the 30000U, but I've tried repairing 3 different 40000Us and was not able to bring back any of them. That's after changing every single SMT cap inside and fully recapping the power supply. 2 out of the 3 I was able to get them to load and eject tapes, but there's just no output or a very faint output at best and the screen remains mostly black.

I was able to get a DH5U parts machine "sort of" working via composite (but no RCA audio), but HDMI and optical audio out don't work after replacing all suspect caps including all of the SMT caps on the digital board. I see there's a DH5U that otherwise works on eBay right now that also doesn't have audio output, so perhaps that was a common problem they could have had.

My general recommendation therefore is to avoid the 30K and 40K series unless you really want a project machine and a challenge. Seems I've seen more repair success stories with the 30K.

I haven't looked at non-electrolytic caps on the power supply, so the 33pF 1kV capacitor mentioned there is interesting, I wasn't aware those tended to go bad or what the symptoms might be if it did go bad?

[jaffa225man]

Quote:

Originally Posted by aramkolt

Since this thread was brought back, I'd comment that I still haven't had good luck with this series of D-VHS machines - can't say on the 30000U, but I've tried repairing 3 different 40000Us and was not able to bring back any of them. That's after changing every single SMT cap inside and fully recapping the power supply. 2 out of the 3 I was able to get them to load and eject tapes, but there's just no output or a very faint output at best and the screen remains mostly black.

My for-parts HM-DH30000U didn't have problems loading a tape, just intermittent analog video output. Since I also couldn't detect its firewire at all being plugged into a Samsung SIR-T165, I replaced all the capacitors on the digital board, and that got the player to interact with the T165, but I still don't see video on the T165 (it probably needs a lot of SMD capacitors replaced too). My fully black analog video issue was fixed by replacing the 30000U's power supply capacitors. It was probably mostly the loose/empty 4700uF, 6.3V C5203 for me, but I replaced everything Blatte listed too. I've tested S-Video and RCA audio as working now, but I've got it permanently set up with component video and optical SPDIF audio.

Quote:

Originally Posted by aramkolt

I was able to get a DH5U parts machine "sort of" working via composite (but no RCA audio), but HDMI and optical audio out don't work after replacing all suspect caps including all of the SMT caps on the digital board. I see there's a DH5U that otherwise works on eBay right now that also doesn't have audio output, so perhaps that was a common problem they could have had.

That's too bad as it's the main reason to go with that model.

Quote:

Originally Posted by aramkolt

My general recommendation therefore is to avoid the 30K and 40K series unless you really want a project machine and a challenge. Seems I've seen more repair success stories with the 30K.

I haven't looked at non-electrolytic caps on the power supply, so the 33pF 1kV capacitor mentioned there is interesting, I wasn't aware those tended to go bad or what the symptoms might be if it did go bad?

Yeah, I had seen some working repair stories for the 30000U only, but it is also the "cheapest" (not cheap to me, even for parts) so that made it possible for me to try.

After I replaced my 33pF 1kV cap (with a much bigger, accidentally way overkill 1 "KV" (not kV) capacitor which still fits), I measured the removed one as working fine. I wasn't aware of ceramic or mica/PTFE caps going bad either, but I didn't want to have it apart and then need other components. I also purchased new flex cables because they were peeling on the ends from my multitudes of plugging/unplugging them (I even cracked most of an end off one, and got lucky soldering it quickly-enough to not melt the plastic beyond usability, but replaced it nonetheless). The overkill 33pF cap I got was this, for anyone curios, although I don't recommend it: https://www.digikey.com/en/products/...30JO3F/1918696