Ampeg B-100R pilot light

[drewl]

Anyone know the correct bulb for these?

The schematic just says "to indicator" tapped from the 40v supply to ground through a 220 ohm resistor.

I imagine a 24 or 36 volt bulb should work, but damn near everyone of these I get has a blown bulb.

[g1]

Apparently the stock one was 28V, .04A, T1&3/4. (Eiko 2187)
As you say, they had a high failure rate. Suggest using something higher than 28V.

[drewl]

Great, thanks.
Unloaded there's 36volts there so ill look for a 36volt bulb.

[g1]

The 220R will also drop some voltage when the bulb is in circuit.

[52 Bill]

One of the problems that I see is that people will stick a good old #47 in any socket that it will fit into, regardless of the voltage applied to it. This will cause early failure of the lamp and sometimes damage to the amp.

[J M Fahey]

Personally I'd kludge a LED inside the "indicator" housing and feed it +V rail through 4k7 1/2W resistor.

[mhuss]

Personally I'd kludge a LED inside the "indicator" housing and feed it +V rail through 4k7 1/2W resistor.

+1

[drewl]

Personally I'd kludge a LED inside the "indicator" housing and feed it +V rail through 4k7 1/2W resistor.

hehehe, that's what I usually do.
Blue LED's or white inside the blue tube work fine.
I usually connect it to the correct spot with a couple dropping resistors.

Just thought maybe someone found a good replacement bulb.