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obi1kenobi1 07-03-2014 06:33 PM

JVC HM-DH40000U won't turn on (need advice on capacitors)
Yesterday I really lucked out and found a JVC HM-DH40000U D-VHS deck with a D-Theater copy of Ice Age inside for $3.33. It looks pristine inside but it won't power up at all. I replaced the fuse on the power supply, since that was the easiest thing to try, but it still won't respond in any way.

Given the era in which it was built, I'm assuming that a capacitor or two has gone bad. I can't identify any bad capacitors visually (nothing is bulging or leaking), and I know that with most electronics they suggest you just replace all the capacitors at once to avoid any future issues. I've replaced the capacitors in a computer monitor before and done some other minor electronics repairs, but I'm not sure where to start with this one. I found another thread on this forum from a few years ago that has a list of the capacitors and their locations on the power supply of the HM-DH30000U, does anyone have a list like that for this model? If not, could someone with more experience give some advice on how to go about cataloging and identifying all the capacitors? I'd really like to avoid making any costly mistakes.

volksjager 07-03-2014 09:44 PM

the 30000 and 40000 are notorious for overheating a burning out - ive had several bad ones - in fact got one here now.
open it up and see if that are any burnt/dark areas on the motherboard - especially to the left side of the mech where there are 3 FETS together screwed to a aluminum heat sink(way undersized heat sink this is part of the problem)

obi1kenobi1 07-03-2014 11:37 PM

I think I see what you are talking about, is there any way to repair this or is it a lost cause?

volksjager 07-04-2014 06:50 AM

if the board is burnt looking i would relegate it to a parts deck.
the one i have here go so hot it melted the solder on the FETS
you may find another deck with cosmetic damage or mech issue and make one good one from the 2.

anyone who want to run a 30000 or 40000 should consider installing a extra fans in the case top
a good PC fan blowing on those FETS should help alot
those FETS get incredibly hot - they will give you a nasty burn if you touch even the heat sink
i only buy 30000 & 40000's now if they are very cheap

obi1kenobi1 07-04-2014 11:56 AM

Let's just assume I'm crazy and like to take on projects that are beyond my skill level, is there at least something I could test to see if a repair would be possible? I've been wanting to get into D-Theater for years now but I can't afford to spend hundreds of dollars on a known working player.

volksjager 07-07-2014 08:31 AM

if you are interested i can sell you the broken one i have here - it does turn on so i know the power supply is still good.

obi1kenobi1 07-07-2014 04:52 PM

I don't think I could afford it at the moment, but just out of curiosity how much are you asking?

volksjager 07-07-2014 05:21 PM

i got it on feebay for $50, but you can have it for $40+ shipping

obi1kenobi1 07-15-2014 08:06 PM

Sorry I didn't reply sooner, I got sidetracked.

Someone who knows more about electronics is looking at mine to see what I can try, but I may still be interested in buying yours if they can't come up with anything. They said that the discoloration on the motherboard is very mild and there probably isn't any component failure yet, but it still won't power on so if your power supply is good that may be worth a shot.

volksjager 07-15-2014 08:12 PM

the one i have powers up fine - let me know

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