LPB-2 not boosting — any ideas?

This topic has 7 replies, 3 voices, and was last updated 13 years, 6 months ago by ranjam.

Viewing 8 posts - 1 through 8 (of 8 total)

Author

Posts
November 3, 2010 at 1:09 am #80940

devnulljp
Participant

My old LPB-2 is no longer boosting — it’s at unity volume when cranked.
Mine’s the old PTP wired version, so no board, just a bunch of components wired together. No electolytics to have dried out.Any ideas where to start looking for faults? I don’t see anything obvious…

November 3, 2010 at 2:10 am #112350

The EH Man
Moderator

I would guess either the battery or the transistor.

November 3, 2010 at 2:30 am #112351

devnulljp
Participant

Battery’s good — I tried a few and a 9V adapter via a clip.
Can I test the transistor? (How?)
Thanks

November 3, 2010 at 9:47 am #112357

The EH Man
Moderator

Can you measure the voltages on the leads?

November 4, 2010 at 12:35 am #112373

ranjam
Member

You’ve added true bypass switching, but did you do anything else? It looks like you have the collector on the ‘left’ lead of the transistor, and I’m not sure I’ve seen many transistors that do this. It would appear the pin configuration you have is c-b-e, and it’s usually e-b-c. Everything else looks OK, unless the switch is wired wrong.
Does your transistor say 2N5058? It’s difficult for me to read that, but any 5058 I’ve seen is a TO-39 or soup can.

November 4, 2010 at 2:52 am #112376

The EH Man
Moderator

It’s likely a 2N5088.

November 4, 2010 at 3:03 am #112377

devnulljp
Participant

It’s a 2N5088
Config is

Does it need to be flipped around?

EDIT: flipped the transistor around — BOOST!

Thanks

November 5, 2010 at 1:01 am #112392

ranjam
Member

I’m surprised I saw that. Yet I did, and it is a typical e-b-c small signal transistor. I’m glad it all worked out.
Author

Posts