Kelvin said:
Thanks for the reply Turbokeu, I did notice that the amp stays on for way less time when I have speakers hooked up to them as well.
However, I still REALLY NEED HELP on getting the bulb out. I've tried to pull it out by sticking tape to it, twisting it with plyers, and trying to pull that square metal bracket off. My fingers are simply too fat to grab a hold of it and yank. How do I get this bulb out!?
You don't have to pull out that square bracket.
The light bulb is put in a rubber grommet through the front chassis.
The bulb should simply come out of the grommet by pushing it backwards.
The problem is that it fits quite snuggy (probably kind of 'stickied' to the rubber because of the bulb heath over the years).
On one of my 1060's I could move the bulb just a few mm to the back but it won't come out completely.
As you're going to replace the bulb by a LED anyway, just push it through the grommet by means of a tool that has about the same diameter as the bulb.
There is a big chance that you will break the bulb but we don't care.
Remove remaining glass particles in the grommet hole from the original bulb and we're ready to go!
I don't know about your electronic knowledge/skills so allow me to explain:
Cut the original bulb wires going to the fuse board close to the bulb and stick a 5mm blue led through the grommet from the back.
Add a antiparallel 1N4148 diode over the LED and a 220 Ohm/0.25W series resistor, and solder these to the original bulb wires.
Diodes and LEDs are polarised components, they have a plus and a minus, where the plus is called anode, and the minus is called cathode.
On a diode the cathode is generally marked by a little ring, on a LED generally the anode is the longer wire.
You have to connect the cathode of one component to the anode of the other, and vice versa.
If this sounds complicated to you I will do the mod and post some step-by-step pictures.
Why the antiparallel diode?
A LED is like a diode, it rectifies the AC voltage, BUT as opposed to a diode a LED doesn't support more than 5V reverse voltage. The antiparallel diode takes care of the reverse cycle of the AC voltage and limits it to about 0.6-0.7V.
Why the series resistor?
Like a diode, a LED has a typical forward voltage (for a Silicium diode it is about 0.6-0.7V, for a blue LED it is about 3.4V).
Once the typical forward voltage is attained, a small increase in voltage causes a big increase in current through the diode or LED.
As the supply voltage for the original bulb is about 7.5VAC a LED without series resistor would simply burn out in a few seconds.
The value of the series resistor is not critical, as long as the current through the LED does not exceed the typical forward current (typical 20mA).
For the same typical forward current different LEDS can provide luminous intensities from as low as a few 10's of mcd (milli Candelas) up to several thousands of mcd.
It all depends from the brand/origin/specifications of the LED in question.
The 220 Ohm value for the series resistor is just a starting value (it ensures the current through the blue LED doesn't exceed 20mA), if your blue LED is far to luminous (you don't want to be blinded by the power indicator of your amp...), just try higher values for the series resistor till the luminosity is satisfacting.
This was quite a long reply, don't hesitate to ask further information.
CD
