Author Topic: Advice Required: Where To Source VU Meter Lamps For Marantz 4100  (Read 1459 times)

Offline AudioJunkie

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Hi Gents

I just got a lovely looking Marantz 4100 amp with a Marantz 105 tuner. The 4100 powers up and plays
but unfortunately 2 lamps seem to be dead on the 4 VU meters. They are the normal kind of lamps, instead
they look like glass fuses that are glowing behind the VU meters. I would like to replace them but have no
idea as to where to get them from.

Can anyone help me out? If I'm not mistaken they are 8v 200ma. If anyone can supply me or point me in the
right direction so I can go buy them this weekend.

Vishen

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Offline AudioJunkie

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Re: Advice Required: Where To Source VU Meter Lamps For Marantz 4100
« Reply #1 on: July 14, 2017, 02:29:59 PM »
look like these

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Offline B_Unit

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Re: Advice Required: Where To Source VU Meter Lamps For Marantz 4100
« Reply #2 on: July 14, 2017, 03:37:24 PM »
Hello Vishen,

Mantech has replacements for these but they are not exactly same but they do the job.

Byron

Offline chrisc

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Re: Advice Required: Where To Source VU Meter Lamps For Marantz 4100
« Reply #3 on: July 14, 2017, 04:33:03 PM »
Would you consider white LEDs?  At 8 volts, each one will need a 470 ohm resistor in series
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Offline ScottulusMaximus

Re: Advice Required: Where To Source VU Meter Lamps For Marantz 4100
« Reply #4 on: July 14, 2017, 05:18:48 PM »
I brought in a whole bunch for Family_Dog, he may have some left
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Offline AudioJunkie

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Re: Advice Required: Where To Source VU Meter Lamps For Marantz 4100
« Reply #5 on: July 14, 2017, 06:18:08 PM »
Would you consider white LEDs?  At 8 volts, each one will need a 470 ohm resistor in series

I was thinking of going with LEDs but thought that it won't do justice to the amps originality.
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Re: Advice Required: Where To Source VU Meter Lamps For Marantz 4100
« Reply #6 on: July 14, 2017, 06:19:19 PM »
I brought in a whole bunch for Family_Dog, he may have some left

I will contact FD as a last option as I would like to get some tomorrow so I can continue working
on the amp and hopefully complete by this weekend. Thanks Though
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Re: Advice Required: Where To Source VU Meter Lamps For Marantz 4100
« Reply #7 on: July 14, 2017, 06:20:04 PM »
Hello Vishen,

Mantech has replacements for these but they are not exactly same but they do the job.

Byron

I think I will have to make a turn pass Mantech tomorrow then, not happy about the drive
but I can't be such a lazy bum lol
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Offline skollie

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Re: Advice Required: Where To Source VU Meter Lamps For Marantz 4100
« Reply #8 on: July 14, 2017, 06:42:46 PM »
I once replaced VU meter lamps with what an old tech called "festoon' lamps, very cheap. No resistors required. From memory, they each had a pair of tails or long wires attached and they are quite small. Measure the voltage to the lamps before you buy replacements. Should be somewhere between 4.5 to 7Vdc??

skollie
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Offline B_Unit

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Re: Advice Required: Where To Source VU Meter Lamps For Marantz 4100
« Reply #9 on: July 15, 2017, 06:48:11 PM »
I think I will have to make a turn pass Mantech tomorrow then, not happy about the drive
but I can't be such a lazy bum lol

Its a truly shitty place to drive to but good luck  :dop:

http://www.mantech.co.za/ProductInfo.aspx?Item=14M0100
« Last Edit: July 15, 2017, 06:50:14 PM by B_Unit »

Offline AudioJunkie

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Re: Advice Required: Where To Source VU Meter Lamps For Marantz 4100
« Reply #10 on: July 17, 2017, 11:28:00 AM »
Would you consider white LEDs?  At 8 volts, each one will need a 470 ohm resistor in series

So my treasure hunt for replacement lamps came up empty handed so I'm looking at this option. I might go to Communica
this after to get a few white 8v leds and 470 ohm resistors but I have a question though. What is the resistor for? Is it there
to lower the current?

Also, I have notice that the lamps seem to be connected in series with a resistor connected at the first lamp.

Vishen
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Offline marantz123

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Re: Advice Required: Where To Source VU Meter Lamps For Marantz 4100
« Reply #11 on: July 20, 2017, 09:20:34 PM »
Hi Vishen

The resistor value is based on a simple formula involving two things : the voltage drop rating of the LED that you use and the current that you want it to run at. Standard voltage drop ratings for leds are 1.5v and 3v with 1.5v types being more versatile. The current can be anything from a modest 8mA to 25mA, with some superbright leds having 35mA capability. You can experiment with currents a bit but i have found that 12mA gives good life on an led and is as bright as 15mA which is more the standard current vs longevity combination. The formula is (supply voltage - led volt drop rating)/chosen current (12mA)  = resistor value. 0.25w resistor power rating should be fine here.

Offline marantz123

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Re: Advice Required: Where To Source VU Meter Lamps For Marantz 4100
« Reply #12 on: July 20, 2017, 09:40:01 PM »
Another thing here...if the supply voltage is AC, which i think it is, then you can still safely run the led but may notice some very fast vibration-like flicker at times but its not serious and hardly noticeable to the untrained eye. The diode reverse voltage rejection is sufficient enough and the led survives. Modified a 2215 this way using those 12v flex led strips. Another thing with the 41xx series is the power switch...they pack up and short out..its at least 40yrs old now.(posted a thread here abt this last yr) Vintage TV3 and TV5/TV8 switches work well here as replacements and are available locally at TV spares shops. Replace the switch to be safe.

Offline skollie

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Re: Advice Required: Where To Source VU Meter Lamps For Marantz 4100
« Reply #13 on: July 20, 2017, 10:25:30 PM »
If you decide to use LED's, you can roughen the lenses with 600 grit sandpaper to diffuse the lighting and make it appear as per the original. I've done this with another amp and it works well.

skollie
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Re: Advice Required: Where To Source VU Meter Lamps For Marantz 4100
« Reply #14 on: July 21, 2017, 12:23:45 PM »
Another thing here...if the supply voltage is AC, which i think it is, then you can still safely run the led but may notice some very fast vibration-like flicker at times but its not serious and hardly noticeable to the untrained eye. The diode reverse voltage rejection is sufficient enough and the led survives. Modified a 2215 this way using those 12v flex led strips. Another thing with the 41xx series is the power switch...they pack up and short out..its at least 40yrs old now.(posted a thread here abt this last yr) Vintage TV3 and TV5/TV8 switches work well here as replacements and are available locally at TV spares shops. Replace the switch to be safe.

I went the route of using leds, they were all connected in series and had an 18 ohm resistors at beginning of the first led. All I did
was pop that sucker out and replace it with said 470 ohm resistor, popped in the leds and it's working perfectly!!

I know exactly what you are talking about when you mention the issue with the switch, I can hear that it's struggling to make contact
and turn the amp on. I think I saw switches at communica but I will have to confirm that. The setup looks really beautiful to be honest
and I wish I could keep them but alas, they have to find a new home soonest.
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