MZ-RH10 Short Battery Life.

[Guest Kaidanovsky]

Dear All,

I've just rediscovered my MZ-RH10 as I needed to do some more recording. I also remembered why I hadn't been using it recently. The battery life appears to have gone down the pan. I bought a new Sony battery from the Sony shop here about six months ago, thinking it must be that the batteries I had were dead, but that still seems to have the same problem.

I have no issue with getting the little 'charging' graphic and text on direct plugging in, or using the cradle. Sometimes it vanishes after a few minutes, other times it stays on. Either way, when it goes off and I try to play something, the display says I have full charge. This then visibly decreases over a few minutes and then the battery's discharged! Something else peculiar that may be related is that AA batteries seem to have a shorter lifespan as well.

I've had a look through the forum but can't find someone with the same problem. It has worked, as I've taken the unit all over Europe when I was sleeping rough and recorded a lot and been impressed by the length of the battery life, What can have changed? Something in the unit?

Thank you for any suggestions!

[sfbp]

The on-off of charging is controlled by (firmware-controlled) NVRAM settings which determine what voltage/current levels count as being charged or discharged.

The prevailing fault on all the gumstick-battery-based units is bad contacts on the battery and battery door. Grunge changes the resistance and hence the voltages seen by the firmware. I didn't realise the RH10 has a cradle (the RH910 doesn't). Cradles generally worsen the problem by having more dubious contact points.

So I'd start with something to clean the contacts, and some brand new gumstick batteries.There's plenty available - GP, Vapex, Powerstream to name some non-Sony ones.

Also try the sidecar and a conventional AA as a method of trickle-charging any existing battery, if you are desperate (assuming you have the sidecar).

Finally if all you need to do is wake the battery up, buy an MZ-R90 or R91 (should be cheap) as for some reason they are really good at getting these batteries charged.

Welcome back to the little world of MD!

[trott3r]

Thanks for the tip sfbp.

[Guest Kaidanovsky]

Thank you for the kind comments SFBP. The problem doesn't seem to be with the batteries being so dead they aren't seen - charging often takes some time yet the batteries don't then last once unplugged. I read something on another thread about the AA trick - a clever idea! It's worth bearing in mind, though I don't think it applies in this case as there's no issue with the cells being 'seen' by the unit.

The contacts are clean. At least the one I can see! Is it worth taking the back off to get to the other contact, or does it involve removing most of the rest of the pieces? I had to replace a laptop fan once and to get to it I had to take the screen, keyboard and motherboard out. Other manufacturers let you take it directly out of the bottom! Design, eh...

Do you think that as the potential difference between the source and the cell decreases even a small grimy patch will create an adequate resistance?

I presume the charge voltage cut-off points you mentioned are set by a resistor or two. Could these have drifted? My micro-electronics isn't great as I'm only used to working with valves, but this is certainly a problem I've encountered with them!

Thanks again.

[jim.hoggarth]

It doesn't happen often, but sometimes a totally dead gumstick battery will appear to accept a full charge, but the outcome is as good as a totally flat battery. Probably about one in every 25 bad batteries I come across show exactly this problem.

In your case though, a new battery shows an identical problem. I suggest there is a fault on the charging controller IC. It may be something as simple as a bad resistor or solder joint, of course, but it will be very difficult to find and prove. Personally I would start by swapping out the main board, assuming the battery contacts are in pristine condition. I would also check the batteries out in another unit to confirm these are fine, which they presumably are if the fault is electronic.

But then again, I have the parts and test gear which you do not, I guess. My advice is to get the batteries checked on another unit first. Time to contact a local friend with an MD or CD player which uses gumsticks?

Jim

[Guest Kaidanovsky]

Thanks Jim,

Are main boards available? I've got a 'scope and various meters and have repaired various circuit boards in my time, so could have a go!

However there's a twist to the tale now. I've just bought my first laptop and having discovered a lot of the SonicStage files on my newly built desktop that I transferred from its predecessor required pointing to the right file, decided it'd be quicker to just put the CDs directly into the laptop instead of trying to use the 'Backup' tool. While engaged on this delightful task I kept the old box on 'charge', pressing the button each time it stopped. I then left it on "play" overnight and this morning it still registered full battery! It's now dropped to 3/4. Could it have been jogged back into working? Alternatively it could also provide support for the 'loose connection' theory...

Are they tricky things to take apart? By which I mean once taken apart, are they possible to put back together without a few vital-looking pieces left over?

[sfbp]

I suggest there is a fault on the charging controller IC.

Of course for my part I would suggest that the NVRam settings are now wrong, for whatever reason. Either corrupted, or some resistance has shifted so the "wrong" voltage is now used as the trigger point for turning on or off charge. Following the adjustment procedure in the service manual will (well, may) fix this, if you are able.

[mdenter]

I have a bunch of old gumstick batteries I acquired when buying my MD collection. Most are Sony NH-14WM's, a few NH-10WM's and a couple Panasonic RP-BP61's. Age had caused most of these to hold a limited charge or nothing at all. I first cleaned the ends of these batteries (where the MD contacts the battery) and most accepted a charge better and a few worked almost like new for a year or so but finally started to get weaker. I thought I would have to give up using the gumstick batteries and have use the AA battery sidecar holder, a thought that depressed me. I started to look for a different recorder but as of yet have not found anything worthy to replace my precious MiniDisc recorders.

Then I had a idea. I made a battery holder out of wood screws and wire to hold the gumstick battery and the wires went from the gumstick holder to a wooden dowel the size of a AA battery with the negative and positive wire attached at opposite ends of the dowel. This dowel I inserted into a LaCrosse BC900 NIMH charger I use for my NIMH AA & AAA batteries. Using this makeshift gumstick/AA adapter I ran each gumstick battery through the Refresh cycle of the BC900. The LaCrosse BC900 will discharge then charge the battery multiple times until it has reached the batteries peak holding state. This brought back a couple batteries to allow me to record for at least a hour. Other gumsticks have come back to 45-90 minute play times. This has "Refreshed" these gumsticks to a much better state than they where before. I have been using these refreshed gumsticks for awhile.

Just recently I bought a Powerstream gumstick made by API Batteries and found this battery to be as strong or maybe stronger than the original Sony NH-14WM. I have since bought five of these Powerstream gumsticks and can now use my MiniDisc without carrying a couple spare gumstick's with me. Hope this helps.