Hoffman Amplifiers Tube Amplifier Forum
Other Stuff => Solid State => Topic started by: TerryD on August 20, 2013, 08:18:49 am
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My led light is out and I don't want to burn this succer up. I looked at the manual and can't figure out the ratings for the led light. I know I need them because I had a couple of leds on hand and blew them up..immediately. Thank you Terry
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What LED??? I'm looking at a service manual for Marantz 1030 and there is no LED.
Give us more info. What's the purpose of the LED? Where is it physically located? What size? color? shape?
Post a hi rez pic of the LED as mounted on the unit.
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Thank you for your patience. Then, what I am referring to is the on-off "light" (or whatever it is then) that is just above the on-off switch that actually informs you that the unit is on or off. It is no longer working. It's hard to get to so I clipped the wires and will use those wires to give me somehkind of on-off light outside the unit. Here is a picture if it gets attached. Its the light that isn't working just above the power switch...you'll notice I already have an on/off switch on the power cord to the 1030 as the switch broke a long time ago and getting in there looks to be over my head...but it sure feels nice. On closer inspection I see the light was blue. Any light would do, even on the cord, provided that it wasn't bright so as to be distracting.
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The power indicator light is a small incandescent lamp (not a LED) connected to a dedicated secondary winding on the power transformer. The "blue" color is simply a plastic lens attached to the front panel. Just measure the secondary voltage and get a lamp rated for that voltage (or slightly higher) that will physically fit. Radio Shack may even have one that will work.
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Done. Measured at 7.6 volts. Got a 12 volt minilight at radio shaack..seems to work fine. I even got it in the same position. Seems a little dim. they had bigger 12 volt lights and I will probably get one of those as the hole for the light is quite a bit bigger than the little dot of a light I got. Thank you, thank you.
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They also have a 6 volt miniature lamp with wire leads that would be brighter. I'll bet the original lamp was rated at 6 volts.
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OK..good. The 6 amp was perfect. In fact it was the same size as the old one. When I first looked at the schematic (before I got on here) I thought it was what you said, but I couldn't believe they would devote a whole secondary of a transformer just for the on/off light...I wouldn't have known what to do with it anyways. Thanks again.
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The amp is older than economical LEDs.
High-voltage low-power incandescent lamps are costly and unreliable. A dedicated winding costs little (in mass production) and was not too uncommon.
Next time it fails...
LEDs always need a resistor (or other current limiting).
If you just feed them >2V, they suck infinite current for a very short time.
If you had put a few hundred ohms in series with the LED, you'da been happy(*).
Anyway any time you don't know what you are doing, adding some resistance makes the smoke come out slower and maybe in a cheaper place.
(*)Pretty much happy. If you move your head quick, an AC-power LED flickers and makes strobe-trails. Maybe a non-issue in a livingroom. On a stage amp I chose to add a full-wave rectifier in the LED feed. No filter-cap to fail: less-strobe was better than no-strobe and a new part to fail and plague me in my old age.
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High-voltage low-power incandescent lamps are costly and unreliable.
So the point is the filament is more at risk at a high voltage with less current than with a low voltage with a higher current?
Brad :think1:
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Another Marantz 1030 still in service! I've used mine (bought used) for over thirty-five years now and it still works as new, almost all the other SS hi-fi amps and receivers I've had over the years are long gone.
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Hi-volt low-watt lamp is a VERY skinny filament.
Wants to break when making the lamp; higher cost. Likes to break in service, which means extra care in making to avoid excess complaints; higher cost.
Not so much when you buy one or two. But when you buy a million, you like the lower-volt choices.
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Hi-volt low-watt lamp is a VERY skinny filament.
Ok, thanks.
Brad :icon_biggrin:
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"Anyway any time you don't know what you are doing, adding some resistance makes the smoke come out slower and maybe in a cheaper place." PRR
LMAO!!!
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I'm not sure if I 'know what I am doing' but I will try to contain any smoke coming from 'cheap places' to the jakes, aka outhouse. I mean, just to be safe.
:icon_biggrin:
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I bought two 1030's from the library when they got rid of them for about 10 bucks a piece, twenty some odd years ago. One 1030 runs my front speakers and one my back. The light probably lasted 40 - 50 years...so hopefully there will be no "next time" for me.
Thanks for all the info & help.