Minolta Flash Meter IV won't wake up

[rippo]

So I just got a Minolta Flash Meter IV from KEH. It seemed to work fine and I played around with it for ten minutes or so. It then went into sleep mode and I couldn't get it to wake up! No amount of pushing the "on" button would rouse it, and removing the battery didn't help either. (I don't have the LR44 battery in there as that's just for the optional IR doohicky. Just the AA battery. I did put in an LR44 to see if that made a difference, but it doesn't).

I then realized that if I keep the battery out for an extended period of time, the unit will work again. It resets to the factory defaults (ISO 64 etc) but continues to function until it goes into sleep mode. If it goes to sleep and I hit the on button immediately, it wakes up. But if it sits for even a few seconds, it's dead.

Is there something about this meter's operation that I'm missing? Or it merely a bad meter in need of a replacement? Thanks.

 

[polyglot]

Your AA battery is probably dead. Having it work momentarily then die, only to come back for a bit after resting the cell is classic behaviour of a marginal cell.

 

[rippo]

Unfortunately that's not the problem. I've tried four different batteries, no luck. Same response each time!

 

[chriscrawfordphoto]

Send it to George at Quality Light Metric. He fixed my Flash Meter IV by replacing the whole main circuit board for $100

 

[rippo]

Thanks for the suggestion, Chris! But I'm just trying to make sure this isn't operator error before returning it to KEH. I only paid $75 for it so a repair is out of the question.

 

[Sowers]

I would try cleaning up the battery contacts. Deoxit or similar (or just scratch it with a pocket knife if you're as cruel to your electronics as I am to mine). My Auto Meter IIIF does some wonky things when the battery is low and/or the contacts are corroded.

 

[Jim Noel]

Send it back.

 

[rippo]

Sowers: gave it a try, the first time it seemed to wake up, but then it continued with its bad behavior. There's a window where if I wake it up shortly after it goes to sleep, it will come back. But if it goes longer, it won't come back unless I remove the battery for an extended period of time.

Jim: Yes, that's the conclusion I'm coming to.

Thanks for everyone's input. Time to get a working one.

 

[polyglot]

Bugger. Another vote for returning it - KEH are good about returns.

 

[CGW]

Bought two Autometer IVs used. First was DOA. The second gave totally wonky readings. Suspect long damp storage in the second case since corrosion was evident on the circuit board--nothing to do with battery leakage. Got a Sekonic 558 and never looked back.

 

[rippo]

polyglot: I spoke with them today and they're happy to replace it. Already have another one on the way. Should be the end of the story (cross fingers).

CGW: The 558 is a little more than I want to pay at the moment. I've got a Minolta Flash Meter III that works just fine, except a slider has come off and changing between ambient and flash requires a sharp object! But it hasn't given me problems. Was hoping the "upgrade" would be just as good. Hopefully I find a dry one. Thanks.

 

[CGW]

polyglot: I spoke with them today and they're happy to replace it. Already have another one on the way. Should be the end of the story (cross fingers).

CGW: The 558 is a little more than I want to pay at the moment. I've got a Minolta Flash Meter III that works just fine, except a slider has come off and changing between ambient and flash requires a sharp object! But it hasn't given me problems. Was hoping the "upgrade" would be just as good. Hopefully I find a dry one. Thanks.

Minolta cranked out piles of IVs, so many that I think there was a problem with sample variation(poor QC?)--some good, some not. The older models--the Flashmeter III and IV--may have been better.

I confess to being a Sekonic fan. Have never had any problems with them--ever, even on "experienced" used meters. If $ is tight, the 328 is usually affordable. The 308 is newer and a gem--flash(cord+cordless),incident, and reflected in a pocket-size meter. If you want all this and spot metering, the 508 is a bit more but not outrageously priced used now.

 

[Chan Tran]

I am a fan of Minolta meters but I must say I do have some problems with them. I got hooked on meter when I bought the flashmeter II. It's fine but I trade it in a couple of years later to get the flashmeter III. it too worked great no problem. I got the spotmeter m for spot and it's fine too. But I sold both of them when I got out of photography in late 80's.
I got a $2 garage sale spotmeter m and the display in the viewfinder doesn't work but otherwise is fine. I bought a flashmeter III on ebay and it's ok but sometimes it would give a low reading. Something has to do with how the trigger button is pushed. I got a brand new flashmeter VI and it's ok but I feel I have to push the on button a little long to have it turn on. quick push it doesn't turn on.

 

[rippo]

Thanks, all! My replacement meter will arrive by the end of the week. They've promised to give the 'new' one a re-check, to make sure it's functioning properly before it goes out.

 

[Hitori_hikari]

It seems that unable to turn on the meter is a common problem, and I’ve just met it today.
My guess was the control chip is faulty, but later on I found that it was because of the early micro controller circuit is malfunctioning. Since it relays on auto power-off, extra charge might be left in the components when the meter is off. At this point, the circuit would regard this state as a medium state, which is halfway between on and off. Charge left in the circuit wakes the components, but the potential difference (or voltage) across the microcontroller is not high enough to start the whole meter. Eventually the circuit is stuck at the halfway position until the battery is dead. Taking the battery out for a moment allows the charges to be removed and p.d. across the main components returns to zero, at which inserting the batteries will restart the meter again. Sadly, memory chips at that time are mostly volatile, which means data, stored in form of charges, will be lost when the external power supply goes down. Therefore former data stored will be erased directly, so inserting the battery again acts equivalent to resetting it.
So, according to these, there is one way to resolve this problem. By connecting the positive and negative poles of the battery slot using a conductor (wire, needles, paper clip and etc, as long as it conducts electricity). This step is a form of shorting the circuit, as the external resistance of the circuit can be considered as zero ohm, only internal resistance which is negligible acts. The potential difference will soon be lowered to zero since total electromotive force (e.m.f, also can be called voltage) is zero, so no force is driving the charges and the circuit components are at ‘off’ position.
Hope this helps if this problem re-occurs after nearly 10 years.

 

[koraks]

Welcome aboard @Hitori_hikari
Your lengthy explanation could be rephrased to "remove the battery and leave it alone for a few seconds, then try again with a fresh battery". The shorting of the battery contacts really won't accomplish anything that doesn't already happen automatically after a few seconds anyway. The idea behind shorting the power input would be to discharge any filtering/decoupling capacitors in the circuit. In a meter like this one, this will in total be a couple of dozen uF in total across all capacitors in the circuit; let's say 100-200uF at most. The types of capacitors used will show a significant leakage, so they'll drain within a few seconds at most (most of them will be empty within a few milliseconds).

There's really no benefit to shorting the battery contacts.

As to storage of parameters: the Flash Meter IV is from an era when persistent EEPROM memory was already common in devices like these. In the worst case scenario, it's indeed volatile memory and the meter resets to factory default settings. Not a big deal.

 

[xkaes]

What TYPE of battery is being used? Some devices ONLY work with alkaline. On the other hand some only work with Lithium.

I've got some cameras that are designed for lithium batteries, but will only work with SOME lithium batteries, but not other lithium batteries -- of the same voltage, new, and tested with a voltmeter.

So while the problem is most likely the meter, don't rule out the batteries. Tell us EXACTLY what batteries you have used and how you tested them. Just because a battery is "new" doesn't mean it will work for you.

 

[koraks]

Tell us EXACTLY what batteries you have used

They might not remember after 13 years, and it's been 10+ years since they have signed on to Photrio.

 

[xkaes]

The idea behind shorting the power input would be to discharge any filtering/decoupling capacitors in the circuit

Could the problem be "bad" capacitors in the meter? Minolta has a capacitor problem with many of its X- cameras, as you know.

 

[koraks]

Yes, most definitely. Meters like these are likely to contain tantalum electrolytic caps and those are notorious esp. if they're from the 1980s. You're right about the camera issue; I have one of those and indeed I've replaced a cap on it to bring it back to life. Good call; this might play a role here as well.