Problem with MZ R91

[Mosaic]

Its was just recently that my R91 started to behave weird. When trying to start the unit with the charger plugged in nothing but a gentle tick appears. Also the unit does not recognize or reload any of my fully charged gumstick batteries (which have been reloaded using my other R90s). It won't even make that ticking sound on battery power. When using the battery extension pack the unit works fine.

The ticking noise might be the key to the problem. Any suggestions?

Thanks in advance

[SonicFields]

You may find the contacts in the battery compartment lid becoming a bit corroded - it may help giving them a clean!

[Mosaic]

Thank you for your answer.

I checked the contacts. Those are fine. Like I said, that ticking sound also appears when there is no battery inserted and the unit runs on the AC charger.

[sfbp]

Servo hitting the stop? Where's Jim,he always knows this stuff... but he is missing, sigh.

[Mosaic]

What do you mean by "servo hitting the spot?"

[Mosaic]

There must be some sort of virus spreading among my Sony units. As a matter of fact not only the R91 but also the R900, as well as the two R55s showed the same sympton today. The problem lies in the battery level which as for the old gumsticks is constantly low regardless of the level displayed. Since I am pretty fed up with recharging and re-checking the malfunctioning gumsticks I decided to only run my units on the battery packs from now on. So the ticking sound must be a result of the unit trying to get into the load mode without having enough power from the gumstick battery.

[sfbp]

Solution: use the R91 to charge batteries.

If that doesn't work, you may have to clean the contacts thoroughly. Mind you,the R90 has identical circuitry so use that since you don't mention it as busted.

[Mosaic]

Thank you for your suggestion. The contacts are fine and for most units there is no corrosion. The problem is: when I fully charge a gumstick in my black R90 it works perfectly fine in that unit. When I change the same gumstick to the R55, R91 or R900 the unit will behave like I said before.

[sfbp]

Just to clarify: the fully charged gumstick (from the R90) doesn't last well in those units, but you get full playback life when it's used in the R90 that charged it?

If so, sounds like corrosion. There are two things to do:

1. Take off the battery door (if you don't immediately get it off, don't despair - this may well be the corrosion). Look carefully how it comes off so you can put it back afterwards. Clean the contacts with isopropanol, lift up the springy thingy till it looks like the R90, and use a sharp knife to get any green deposits off if cleaning doesn't work. Check the resistance - you will see that the contact through the door (and all similar doors for gumsticks) is dependent on the hinge, too!

2. get a flashlight and look into the bottom of the battery compartment and try to do roughly the same for the contacts at that end too. Using a knife point to abrade that end of the battery (contact) as well, may help.

If and only if nothing helps and this is a heavily used unit that used to charge things perfectly, take it apart and do the power supply adjustments (only) following the service manual on page 19.

Note that, if the battery itself is really the problem (these batteries can vary widely in history, origin and output) then using one of the intelligent chargers (look up posts by MDietrich) may be a more plausible approach.

I and others have had pretty good luck with the R91.

[MDietrich]

Thank you for your suggestion. The contacts are fine and for most units there is no corrosion. The problem is: when I fully charge a gumstick in my black R90 it works perfectly fine in that unit. When I change the same gumstick to the R55, R91 or R900 the unit will behave like I said before.

The units themselves are at fault here, just like the gumstick itself.

I have the same problem: both my R55, the R91 and both R900 won´t work with a fully charged battery. Have a look at the contact in those devices not able to run on a gumstick; it´s just a tiny tip of metal which wears down over time. It behaves like a spring and looses its elasticity over time, preventing firm contact.

To avoid this I bought self adhesive copper foil, something like this: http://www.ebay.de/itm/2m-selbstklebende-kupferfolie-80mm-breit-/181351987183?pt=LH_DefaultDomain_77&hash=item2a396bb7ef

I subsequently fashioned a tiny piece of thick copper out of this foil which fits into the battery door of those units. The copper will re-establish connectivity.

The second problem is the battery itself: any NiMh battery does have some sort of Memory Effect (not like on NiCd batteries), to avoid it you´d need a charger that has a 'Refresh' function. I´ve bought this one three years ago: http://www.amazon.de/Technoline-BC-700-Akku-Ladeger%C3%A4t-schwarz/dp/B000WILI42/ref=sr_1_8?ie=UTF8&qid=1394886466&sr=8-8&keywords=eneloop+ladeger%C3%A4t

It´s wonderful: not only does it charge other NiMh batteries to their optimal power, with two wires, a dummy piece of rubber and a claw it´ll refresh the prismatic gumstick batteries as well.

[Mosaic]

Both sfpb and MDietrich, thank you for your comments. I will take your suggestions into account in terms of the battery related problem. First I will recharge my gumsticks using the special charger which a friend of mine will borrow. Second i check the connections and may fix the compartment doors using the copper foil. If all of that wont help for any of my units the problem might be the unit itself. Another hint for that can be that the same ticking sound problem appears when there is no gumstick inserted and the unit runs on the charger. I'll keep you updated since i might not be the only one experiencing those problems.