Gibson G30

[pnut5150]

What are the transistors used in g30 for power amps? One is marked ER3055, the other is worn off. What are my replacement options?

[Jazz P Bass]

Gibson G30 Schematic

The ER3055 is a 2N3055G (NPN)
It's mate (which is no longer available) crosses to a MJ2955G.(PNP)

Both are available at DigiKey.
2N3055G ON Semiconductor | 2N3055GOS-ND | DigiKey
MJ2955G ON Semiconductor | MJ2955GOS-ND | DigiKey

[pnut5150]

Thanks!

[pnut5150]

BTW..does it matter if the G is on the end?

[J M Fahey]

BTW..does it matter if the G is on the end?

No, the important data is "2N3055" and for that amp is enough, any of them are overkill (good )

I know 2N3055E which means Epitaxial, the current manufacturing process for the last 20 or 30 years, and 2N3055H , the original 45 year old process, which yielded much more robust ones but which cost twice, so hasn't been around for ages.

UPDATE: G means Lead Free and works exactly the same as others.

Attached Files Attached Files

File Type: pdf G10,G20,G30.pdf (430.0 KB, 0 views)

Clicking opens the infamous MEF black page with 1 pixel black dot in the middle

[g1]

Try this one:

[pnut5150]

I am trying to fix the pilot lamp, it had a Christmas tree bulb in it..I replaced it with a led with a resistor, it will burn a few mins and then burn out..what can I do here?

[J M Fahey]

I am trying to fix the pilot lamp, it had a Christmas tree bulb in it..I replaced it with a led with a resistor, it will burn a few mins and then burn out..what can I do here?

PL1, clearly labelled NE-2H is not a "Christmas tree bulb" but a 90/150VAC neon lamp.

which, of course, is perfect for 120VAC mains.

You tried to use a LED which uses some 2V DC and stands some 10V reverse voltage ... you are sending it some 160V reverse.

It's a miracle that it stands even a few seconds.

[pnut5150]

Thanks for the info! Couldn't get any type of power reading where the light wires in. I could ground the led to chassis and it worked great, but it would turn off unless amp was unplugged. Is there any way to use a LED in this set up?

[Jazz P Bass]

In my opinion you are best off using a neon lamp.

Going across the 120V line with an LED is simply not safe, although it can be done.

Most circuits will include a dropping resistor, a diode, a capacitor and a FUSE.

AC Line Powered LED Pilot Light - LED_and_Light_Circuit - Circuit Diagram - SeekIC.com

Boat-Project.Com - Creating a 120VAC LED Panel Indicator

[J M Fahey]

I could ground the led to chassis and it worked great,

Please DON'T !!!!
One end is live 120V mains, you are grounding the other end

You have 2 options:

1) use the proper neon bulb (you can mail order 10 of them, they are very cheap, and you keep others for future use) and you wire it as original with a 100K resistor in series

2) empty that pilot light housing, absolutely disconnect it from mains voltage, and put inside a Led with a 4k7 resistor in series, fed from +V (48VDC?)
Led cathode now can be grounded.

When turned OFF, LED will still shine for a few seconds, while supply discharges.
It's normal.

EDIT: @ G-ONE : can you please post the other half of the PDF?
The one with parts values.
Thanks.

[g1]

That schematic is from the Gibson site, it's the only one I've seen.

[pnut5150]

What is this? Was trying to figure out tremolo (does not work) and broke legs off this and no no sound. I am assuming a germanium transistor?? How do I tell what size? Model number?

[pnut5150]

I did order the correct bulb thanks for the info

[52 Bill]

[ATTACH=CONFIG]32695[/ATTACH]
What is this? Was trying to figure out tremolo (does not work) and broke legs off this and no no sound. I am assuming a germanium transistor?? How do I tell what size? Model number?

Which transistor is this? The schematic lists the numbers of each of the transistors along the bottom of the drawing.

Try and figure out if it is Q4 or Q2 or whatever and then look up what the part number is.