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Thanks for the cleaning tip even though the terminals looked clean they seem to charge better after an alcohol swab cleaning.

That in turn tends to suggest that adjustment will help. Cleaning often reduces resistance and can make a few millivolts difference, corresponding to the circuit firing (or not).

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  • 2 weeks later...

I actually find that difficult to believe. I have seen many hundreds of these batteries, and never one that has so much plastic wrap stacked up on the top that the battery terminal will fail to make contact. You are writing about the positive terminal, are you? The one with the metal cap, not the flat end that forms part of the battery body? Perhaps the actual problem is that the battery contact is bent flat, or even backward on itself and pushed into the supporting plate, a condition I have seen several times. I would be grateful if you could confirm this by looking again at the battery contact, or even sending me a PM with a close-up photograph.

Jim, I found that thread. It's the user "This Sucks" that told me the trick. You were on that thread as well.

I can take a photo next time I hop over here. But it's exactly as per what "This Sucks" said. I use a knife to cut out the very top, that originally c/w a white paper top at the +ve terminal, and I also cut out the plastic wrap at the very top. There is no trick to it. It simply works

And that's not all, my other 2 older batteries purchased May 2010 that I thought is toasted, I did the same thing above, 1 of 2 now charging much longer than before, and it's fully functional, the other 1 is indeed dead.

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  • 1 year later...

Sorry to resurrect an old topic. This matched a search against "charging problems with N710".

I have just taken delivery of a N710 (eBay) which refuses to charge the gumstick (Sony NH-10WM) battery (the seller stated as such). Power via mains or AA battery pack is fine.

Jim, I would be interested in the Service Manual procedures you mentioned to get this unit charging again.

Were these units not built in Japan? I can not find country of origin on the unit itself (unlike the R900 which has "Made in Japan" etched into the back).

I only bought the N710 as Type-S would give me better on playback of LP2 but if the units of this vintage are unreliable in charging then maybe I should stick with my "simple" R900!

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An alternative is to use the Japan made unit to charge the battery.

You will be able to do so (with the 710) better if you do the adjustment in the manual which is in the SM. Or Jim does :) But mostly it may be a matter of contact resistance. What you are adjusting is the voltage level(s) at which charging kicks in or out.

Hope this helps.

Stephen

PS the service manual is freely available here. I never before noticed that the 710 page didn't have one - it's the same unit.

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An alternative is to use the Japan made unit to charge the battery.

You will be able to do so (with the 710) better if you do the adjustment in the manual which is in the SM. Or Jim does :) But mostly it may be a matter of contact resistance. What you are adjusting is the voltage level(s) at which charging kicks in or out.

Hope this helps.

Stephen

PS the service manual is freely available here. I never before noticed that the 710 page didn't have one - it's the same unit.

Thanks Stephen.

I was not clear in my original post: What I meant is that the unit will not take power from the internal gumstick battery. eg. with only the gumstick as power the MD will not operate at all.

I have tried wiping the battery door and battery chamber floor contacts with IPA and a qtip. There are not obstructions in the battery chamber I can see (I also compared it to my known good R900, it seems the same).

Earlier in the thread Jim mentions weird behaviour with a series of known good batteries and this unit. I have also sent Jim a message via his eBay MD repair listing. Let's see.

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Hi Imran, Stephen et al.

Just checked the N710 service manual and I can see from the circuit diagram that the external DC inputs and the AA add-on battery are effectively in parallel. The internal NiMH battery, however, is connected directly to IC951, the battery charging control IC. I would guess the likely culprit is this chip. So presumably the recorder will need a board replacing. I will contact you via Personal Message, Imran

Jim

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What's IPA? Where I come from it's India Pale Ale, but maybe you mean (CH3)2-CH-OH?

My experience is that it is necessary to score the terminals of the gumstick with a very sharp knife to break the build up of metal oxide or chloride (green) or whatever.

If this is happening with a known, working battery that is charged, there are two more things to try to fix:

1. the contact on the bottom inside i.e. the part touching the -ve terminal

2. the (sliding) mechanism in the door. There are two aspects to this:

a. cleansing

b. making the spring bent enough so that it pushes on the battery +ve terminal hard enough

You may have to be rougher than you think :)

Hi Imran, Stephen et al.

Just checked the N710 service manual and I can see from the circuit diagram that the external DC inputs and the AA add-on battery are effectively in parallel. The internal NiMH battery, however, is connected directly to IC951, the battery charging control IC. I would guess the likely culprit is this chip. So presumably the recorder will need a board replacing. I will contact you via Personal Message, Imran

Jim

Oh well, THAT's another possibility I had not thought of. But before it gets replaced I wonder if it degrades, hence the necessity to adjust the unit to get it back to functioning.

I'd still be inclined to use a bit more pressure when cleaning, and the knife point may well be more important than the isopropanol in this regard.

Stephen

PS. Jim could this chip get blown if someone tried to charge a dead battery?

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What's IPA? Where I come from it's India Pale Ale, but maybe you mean (CH3)2-CH-OH?

:-D

IPA aka Isopropyl Alcohol.

I bought a spray can of this as it's good for cleaning electrical contacts and as a general cleaner to get sticker residue off plastic etc.

So charging circuit is likely culprit :-( thought so...

Thanks guys.

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