Could you advise me on a Preamp replacement?

[SBassman]

Anyone with good background to advise me on a preamp replacement?

It's on a Sinsonido bass. I know most of you won't be familiar with them, but:

It has two condensor mic pickups in the bridge that run to the preamp.

I am attaching below two images. An image of a properly wired preamp, and an image of a new preamp that will go into bad bass #2. [preamp has hum/ground problem of some sort.] I circled pickup connection points in each picture.

1. I will have to snip the pickup wires on the bad bass. At that point, I won't have enough slack to wire to the new preamp. So, I imagine I will have to solder more length on, then solder to the connections on the board. Yes?

2. The wire has two wires inside - a single lead, and another covered wire. I'm used to seeing a lead and a multi-strand outer layer. What is the name of this wire that they are using, and where do I get it?

3. The pictures are not very good, but please try to see the 4 square connections on the new preamp. Two connections from each pickup go to each pair of squares. The middle squares are reallyclose together. Should they actually be connected with solder, or should they not touch?

Anything else you can advise me on would be appreciated. Thanks much.

[pocket_groover]

Frank, I PM'd you with the following instructions:

What I did was to de-solder the wires coming from the pickup. All you do is heat up the connection on the underside of the board. Take the board out first. Undoing the pot nuts will release the board. The power wire from the battery has a plug which you can just pull out. The wires then have the same length and you can just solder them to the new board by passing them thru the correct holes and applying solder on the underside of the board.

Re-assembling is then plugging back the power plug in to the jack and then securing the board via the pot nuts.

Let me know if there's any questions..

[pocket_groover]

Frank, I just took a look at my old preamp.

1) I made a mistake; there are no thru holes. Just tack solder the wires to the board.
2) DO NOT snip the wires. If you just unsolder them, it should be the right length for the new board.
3) The two middle ones are the ground wires that should go to the shield of the pickup wire. They are connected together.
4) Since the new preamp also comes with the 1/4" jack, you need to take the old 1/4" jack out as well. Just install the new one in it's place.
5) As for the covered wire, I think it's the shield wire (multistrand with heat shrink?). If the covered part goes to either of the middle connections it's the ground. Otherwise it's the hot wire.

Let me know if there's any questions.

[SBassman]

Getting close to a gig for this evening, so I won't be opening up my basses but, first thing tomorrow, with the gig behind me, I'll start the operation. Thanks for the exchange on it. It will hopefully keep me out of trouble.

One last thing I should have focused on when I had them open last time: if I am remembering correctly, the ground part of the connection touches both the hot square and the ground square, in a sort of daisy chain.

1. Am I remembering correctly, and if so, is that the correct wiring, to sort of make a loop with the wire, touching down on both the hot square and the ground square?

2. Am I reading your response correctly that the two middle ground squares should be connected? Do I accomplish that simply with a blob of solder between them?

Thanks.

Everyone - in the U.S. anyway - enjoy your Memorial Day weekend.

[pocket_groover]

Hi Frank....

As far as the two middle ones I think they are already connected. I'll take a good look again and try to get a little clearer explanation up later today.

Have fun at the gig!

[SBassman]

Gig was a blast. In our band, we win some and lose some.
We have very enthusiastic crowds at times, and other times nobody responds.

Last night we had a super enthusiastic crowd. It was tons of fun.

Ok, news update: the operation was ...

A Complete Success.

I'm very happy about it.

PG - thanks for all the consultation. Very much appreciated.

Have a great weekend.

Frank

[pocket_groover]

Congratulations! I assume all the noise/hum is gone? If you'd like a spare preamp handy, I could probably repair the old one you have. Just let me know (PM).