Andy's Techie Stuff

They will be brown-black-red 1Kohms. However they will be across other comps, so don't worry about in/out of cct readings.- If they're there then the mods been done- don't risk damaging the board- new ones are not available!

thanks for all your help so far but now i think i have another problem.

i changed the capacitors and that did nothing so i thought i would change the resistors, i know you told me not to but i was going to throw it away if this didn't work so i had nothing to lose. The unit now does its loading thing but after a while it turns off and when you press power the JVC DVD video recorder splash screen comes on and then just repeats itself forever. does this mean that it is trying to load something from the hard drive and failing to do so? the DVD and HDD buttons work but the eject button doesn't (it doesn't even work if you press the button on the actual drive itself) even if the dvd drive doesnt work i would probably use it as a hard drive recorder anyway so i don't care too much about that.

May be the HDD is corrupt.
There is some software to sort this if this was perhaps the problem

is this software available for download or do i have to go and see my local JVC dealer?

Andy, hope you can help.

We have been experiencing problems with our DR-MH20 since yesterday

The recorder does not stop displaying 'Loading' anymore. Restarting the recorder by pulling the electricity plug and reconnecting does not help. I've been reading the articles in this forum and the problems sound alike but are not exactly the same. Have you had experiences like this before. Can you help and tell us what to do to get the recorder going again.

Thanks in advance
Walter

Sorry not to reply earlier.

Its most likely now due to age etc and the higher temps in the last week etc that you have a power supply problem (rather than the resistor mod problem).
You will need an experienced tv engineer to do this repair, its not a DIY job.
Several of the capacitors in the power supply eventually 'dry out' due to running at quite high temps for the last ~2yrs. Its also likely that the main power reg IC will have been running over hot too and its best to replace this at the same time (saves it going again soon) Often this has been running too hot since its not been seated closely enough to the heatsink- there is a burr that needs taking off.

Attend to these and it should be fine again. :D

I changed the 3 small 680uf capacitors and the bigger capacitors (between 1000uf and 1500uf) and that has not done anything, i'm quite good at electronics and soldering so if someone could tell me where to get the new regulator that would be greatly appreciated. i'm assuming its the one connected to the heat sink (IC5101) when its put back on would putting some thermal compound on it help to prevent against heat issues a bit more?

even if i can't fit it myself providing the component to the repair people would cut down alot on their inflated component cost.

This looks like a corrupted HDD. Often happens due to lightening strikes or surge in the mains supply. There doesnt need to be an audible nor visible thunderstorm in the area for a strike to hit.
Many of these problems can be largely avoided if you fit a surge protector to your most vulnerable equipment.
The now infamous `loading` problem in HDD recorders is attributable to one of three main components.
(1) The PSU which suffers from dried out `Lytics and not just the big secondary`s
(2) The Digital Board. The Mod to fit 2 or 3 resistors is little more than a stop-gap to fit a plaster (band-aid) on a failing PSU.
(3) The HDD itself. The JVC software usuallly makes a good fist of repairing this and keeping the original recordings intact. However, it will not repair all corrupted HDD`s. Other methods have to be employed here.

Can the HDD be restored to factory condition without being sent back to JVC?

Officially, no. If it`s under warranty then you should make use of it and let JVC correct the problem at their expense, and unfortunately your inconvenience.
If the unit is out of warranty, then either JVC or a JVC approved service centre is your next port of call. You bear the cost.
The last option is to find some kindly soul with the neccessary tools.

i bought the unit at a bootfair so i have no proof of purchase. i'll wait for the voltage regulator to arrive before i start reformatting and reinstalling system software.

If the Regulator (STRG6653) has blown, it will have taken a few other components with it, which will need replacing.
Reformat with which filesystem ?
I assume you know it isn`t a Windows/Linux system

i've changed some capacitors but not the regulator. does that mean i might have to replace the capacitors i've already replaced because the regulator has messed them up again?

and yes i know its not a windows format, but wouldn't that be great if it was. plug in the hard drive and it asks you if you want to reformat it in:
1) FAT32
2) NTFS
3) JVC Proprietary format

ill look into the file system if the regulator doesn't make it work.

I read your previous posts regarding your unit.
When you power the machine on from cold, and once the 50 second `Loading` has stopped, do you get dashes in the front panel display ?
The firmware the unit needs to start is all located on the HDD. So if you get the unit to a STBY condition this would indicate at least the HDD has loaded the firmware correctly. If the firmware is corrupted then it would be in continuous `Loading`.
The IC Regulators in these PSU`s either work or dont, unlike the Panasonic units which die a slow death. I`ve repaired many with a blown Regulator, the hole through the Plastic IC is a bit of a giveaway
As your unit powers to some stage, it means your Regulator is OK for the moment, however changing it is never a bad idea. It wont affect your previously changed Caps though.
Which electrolytics did you change ?
Do you have access to an ESR meter ?

i have changed the 3 16v 470uf capacitors by the small digital processor board and i have changed 5 bigger caps ranging from 1000uf to 1500uf by all the diodes near the transformer. there were also 3 caps on the board that were tested and proved to be faulty. i'm quite sure that the IC has blown because the heatsink is live, i accidentally found that out! .
and no the dvd player does not get out of its loading cycle.