DVM decimal system

Discussion in 'Amp Tech Center' started by TwoBear, Jul 27, 2021.

  1. TwoBear

    TwoBear Tele-Afflicted

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    Dumb attempt to pull in Dewey decimal system for a title. My serious question is with my meter set like this with a reading of .02 when I’m set to DC current, would that be close to 200 mA? I didn’t want to try it on the 200m setting for fear that I would blow the fuse. I know it’s tens hundreds, but I had a stroke a while back and sometimes I think of things completely juxtaposed & Caddywampus. It’s easier just to double check, at this point I don’t care if I seem to be an idiot. Thanks. Edit-The picture is underneath I don’t know why but it would not print with this
     
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  2. TwoBear

    TwoBear Tele-Afflicted

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    I don’t know why it didn’t print the picture with it image.jpg
     
  3. J. Bonkosky

    J. Bonkosky Tele-Holic

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    That is 20mA.
     
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  4. dsutton24

    dsutton24 Doctor of Teleocity Ad Free Member

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    Never mind, misread the OP. .02 on the 20 amp range would be .02 amps, or 20 ma. If you want 200 ma, you want it to read .200.
     
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  5. kbold

    kbold Friend of Leo's

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    Yep 20mA. You could use the 200mA or the 20mA range (If it's actually below 20mA).
     
  6. TwoBear

    TwoBear Tele-Afflicted

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    That seems so small. It was the draw I was measuring from the charger to my Crate Limo battery powered amp. It calls for a 15 volt two amp charger and all I had was one that was labeled as 15 V but it was non-regulated. It only had a 1000 mA specification. It actually measured 19 volts output. I’ve had it on the charger all night as it says to do with it run down. It may be time to buy another battery for it. It was about 10 V and change.
     
  7. dan40

    dan40 Friend of Leo's

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    The charger will not deliver it's full current rating if it's only plugged into your meter. It will only deliver the amount of current that the circuit demands from it. It's similar to how the PT in an amp may be rated for 200ma but the tube amp may only draw 100ma from it under normal use.
     
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  8. TwoBear

    TwoBear Tele-Afflicted

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    I was just checking, I took out the meter and put it back straight to the charger. I don’t have the factory charger but I figured somewhere in the 19 V overage and the one amp ‘underage’ it might even itself out. It seemed that the internal battery had 10 V and change charge and the charger dropped down to 9 V and 20 milliamperes when charging. The instructions called for a 15 V two amp charger, and a 12 V 1000 or 2000 mA ‘run’ Power supply. I’m aware I’m interchanging the milliamps and amperage terms. I should just invest in a proper charger and a new battery and stop trying to make do with under Spec things.
     
    Last edited: Jul 28, 2021
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  9. dan40

    dan40 Friend of Leo's

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    Just be sure to use one that supplies at least the minimum required amps at the correct voltage. If it's rated to low on amps, the charger will overheat and it will also cause the voltage level to drop under load.
     
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  10. TwoBear

    TwoBear Tele-Afflicted

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    Yeah that’s exactly what seems to be happening it’s not really overheating it’s just a little warm to the touch I mean just barely but it’s obviously not capable of delivering what the battery wants, or maybe more to the point what the system is designed to supply. It’s probably what led to an early demise of the 12 V sealed lead acid battery inside the amp. I thought With a charger that was under/lower spec for current it would just take longer to charge.
     
  11. TwoBear

    TwoBear Tele-Afflicted

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    It’s getting to be an old amp with some of the pots and Rotary encoder/pots needing Finesse and in a couple places actually needing a rubber band to hold them still as they can go a little wonky even after A thorough cleaning. I guess it’s possible that the charging system might not be up to snuff also. I’ll try and source a proper charger 15v fixed output with a two amp current. Or a 7815 hi current Power transistor, as I think I have some 18 or 24 V two or 3 AMP Power/chargers around here. Just have to sort through some junk drawers.
     
  12. Lowerleftcoast

    Lowerleftcoast Friend of Leo's

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    The schematic shows a cigarette lighter input. Is there a problem with using your 12v vehicle to power/charge this Crate?
     
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  13. TwoBear

    TwoBear Tele-Afflicted

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    Yeah I can run it with a/the 12 V Supply side or run side, my problem is with the 15 V charge side. If you’re referring to taking it outside and running it from a 12 V battery image.jpg into the 12 V “run side” that’s definitely something I’m thinking of. In a different thread I got into this plastic ammo box that houses a 12 V 7.9 Ah SLA. It has 9 V output for my pedalboard, but I could tap it straight from the battery before the 7809’s.
     
  14. Lowerleftcoast

    Lowerleftcoast Friend of Leo's

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    Mainly I was thinking of the charge side. A car battery charger should be able to get what you need. It may not be right at 15V but it should be close enough.

    My second thought was to power it externally but you have already been working on that solution.
     
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