Author Topic: The other side of PF-6B (Read 903 times)

basser · « **on:** August 19, 2009, 07:49:30 AM »

Hello again to all Alembic lovers!

I've noticed that there are 3 trim pots (2 in blue and 1 in green) on the other side of my PF-6B preamp card where the hum balance and gain controls are. The trim pots are visible when the preamp cavity is opened, while the card is still attached to the plate. (Please find attached JPG file for your review.)

It would be much appreciated if you experts out there could kindly provide some information on what those trim pots are for and how to control it (or better not make adjustements).

Many thanks,

Andrew

jacko · « **Reply #1 on:** August 19, 2009, 07:57:44 AM »

Hi Andrew.
I think you'll find that they're all blue. These are the trimpots used to control the 'amount' of signal coming from each pickup. There's an FAQ thread here.

Graeme

David Houck · « **Reply #2 on:** August 19, 2009, 08:13:49 AM »

Graeme; on a PF-6, the trim pots you've referenced are on the the other side of the card and are available for adjustment through the holes in the cover plate. I don't think the trim pots pictured above are the same thing.

georgie_boy · « **Reply #3 on:** August 19, 2009, 08:28:07 AM »

Looks decidedly odd to me!!??

mica · « **Reply #4 on:** August 19, 2009, 08:35:22 AM »

NOOOOOOOOOOOO
Do NOT adjust these trimmers. These are part of the calibration for the high frequency noise cancellation network and are not user servicable. In fact, they are usually covered with strong stickers to discourage fiddling.

basser · « **Reply #5 on:** August 19, 2009, 08:55:40 AM »

Mica and Dave,

Thank you very much for your prompt support and advice. I've been reading lots of other materials from you and it is sure helpful a lot.
And thanks to other members as well!

Should I cover the trimmers with stickers/tapes or would it be OK as current?

Andrew

mica · « **Reply #6 on:** August 19, 2009, 09:16:33 AM »

Only need to cover them if you ask someone else to service your bass or if you sell it.

jazzyvee · « **Reply #7 on:** August 19, 2009, 10:13:41 AM »

Is that all the electronics for the Series bass or are there more hidden in the body somewhere else apart from the control cavity where the knobs are.?
Jazzyvee

(Message edited by jazzyvee on August 19, 2009)

mica · « **Reply #8 on:** August 19, 2009, 10:21:19 AM »

There aren't any hidden electronics in a typical Series I or II bass or guitar. All electronics have access panels so repairs are possible.

jazzyvee · « **Reply #9 on:** August 19, 2009, 10:36:10 AM »

I'm just surprised you get all that sound from apparently so few components.

I plan to give you a call in a bit Mica once I finish my dinner.

Jazzyvee

basser · « **Reply #10 on:** August 19, 2009, 03:13:24 PM »

Dear Mica,

Thank you again for the clarification.

It's always great to know that your ultimate builder is there for you!

Andrew

jacko · « **Reply #11 on:** August 20, 2009, 12:54:04 AM »

Oh dear. I'm hanging my head in shame now. Just as well Dave and Mica were on the ball or my mistake could have caused untold suffering ;-(

Graeme

p.s. They still all look blue to me ;-)

georgie_boy · « **Reply #12 on:** August 20, 2009, 04:19:33 AM »

I'd never seen the circuit board with the calibration fitted either!
Now we all know what to look for.

G

David Houck · « **Reply #13 on:** August 20, 2009, 07:35:14 AM »

That's ok Graeme; let me get you a beer.

jacko · « **Reply #14 on:** August 20, 2009, 07:51:23 AM »

One of these days I'll be in a position to take you up on that Dave ;-)

graeme