Tips on fixing JVC HR-S8000U dim VFD display?
 

Hello,

My S8000 front panel display gets gradually dimmer as you go from right to left. I've read variously that this is a problem with dirt or leaky caps on the power supply board. Anybody have any tips on where to start? I have basic soldering skills but am not able to really read schematics. Should I just go through and replace all of the electrolytics I find on all the boards? Thanks in advance!

Matt

The most obvious method is to simply look for bulged or leaking caps -- possibly even caps that simply look odd.
Then replace them.

It's really not any different than the methodology used to repair JVC DVD recorders.
And we've archived quite a bit of info on that topic here: http://www.digitalfaq.com/forum/home...g-jvc-dvd.html

So open it up, and see what you can see. :)

Me too, but the thing is I unsoldered and checked EVERY cap (>13) on the power supply with a capacitor meter and only found 2 small light green 22-50Vs that were out of spec (15uf and 12uf) so I replaced them with spot on 22uf AL caps and there was no change. I have all on order (<$10.00) so Ill get in there and replace them all again which is no small job but I at least have all the sockets retainer tabs pre-broken(!) for the small 24g wires that come off the P/S. They mounted them so the tabs were inboard so you cant push them in to release....I checked the display board voltage and got -30V AC coming in on the red wire only.

Hi, I just bought one of these for a good price and have the same issue with the display. I am not seeing anything obvious on the boards could it be the actual display is bad? Is that very common with these types displays?

Yes, I am getting the feeling the displays are just worn oit, or maybe more accurately described by another poster as oxidized and in need of a burn off by a high voltage across the filamant/cathode like the internet shows. Do a youtube search for vfd burn up and you'll find a guy that does about 6 in 10 sexonds. Trouble is I don't know what kind of power he is using as I tried a 12v 8ah ups battery across the filament and didn't get anything glowing...? You may be able to fashion a new display with another vrs display that has similar symbols but you'll be breadboarding it big time. I recapped a Sanyo vcr and it totally fixed it's display but not this time.

I know it's a late reply but take a look at this video: The VFD don't work (or very dim), the ESR testing is useless in this case. Turns out a capacitor is shorted.

https://www.youtube.com/watch?v=tcWQ...nn8iFw&index=1
(by 12voltvids, Technics STS 707 Dim display repair )

Those fluorisent displays loose maybe also their vacuum ? or metal particles get vapourized

Ill check those Caps that supply the VFD the high voltage.I checked the display board voltage and got -30V AC coming in on the red wire only. This VCR is literally wall to wall through hole components on multiple stacked boards so its gonna be a challenge to find them. Pretty far back in the load for stuff I'm looking at repairing.

http://www.digitalfaq.com/forum/imag...RS8000U7-1.jpg

Though this forum post may be old, I'd like to contribute some insights for future readers encountering similar issues. First, I highly recommend watching an excellent video on repairing dim or dead vacuum fluorescent displays, like "Pioneer D-07 DAT dead vacuum fluorescent display repair." Although it focuses on DAT machines, there's significant overlap with VCRs. It's REALLY good!

Specifically, I work with JVC VCRs, but the knowledge can apply to various makes and models. Here are my recommendations:

• Invest in Adobe Acrobat Pro for scanning and making text searchable, which is invaluable for troubleshooting.
• Obtain the service manual for your device, make sure it has schematics (e.g. "Switching Regulator Main Schematic"), which you can find through online searches. Some of these service manuals out there don't have schematics, but luckily many do.
• Utilize Adobe Acrobat Pro's "Poster" option to print out large-format schematics for easy reference. It's really easy with this to see how things flow, and what a culprit to. If you want to save trees, no problem, it just helped me to write notes and highlight elements of the schematic as I followed the path.
• Pay attention to voltages; vacuum fluorescent displays typically require higher voltages (e.g., -29V some JVCs, look for large-ish negative -27, -29 and -31 numbers specifically). Once you find this start following the path these negative numbers follow, identifty diodes, resistors and capacitors in the parth that may be the culprit. In my case, it was a bad resistor - which meant zero display. But a bad capacitor may mean a dim display.
• Watch the recommended video for effective troubleshooting techniques using the schematic. He explains it well and get it DAT machine running like a champ.

Hope this is helpful for future readers. Happy fixng!

My display is just dim. Flashing 12:00 AM for 30 years for the PO probably did it in!