Sterling SUB bass- active electronics stopped working

[bassman]

I have taken up this project again and I have tried to shoot some pictures of the control circuit on this bass.
A possible coomplecting factor in the repair is that the bass has three tone controls not just two as on a Sub Stingray bass. I have heard that his requires a different op amp (chip) than the 4250.

I just can't make out the numbers on the chip. I will try to magnify it and get the right replacement chip for it.

I really need to put in a 8-pin socket so that I can change out the chip if this happens again.

Pictures of my bass are coming, I am posting this from work and I have to hook up my camera to upload the pictures.

[deltafred]

bassman

Yea, the 3 band uses a dual op-amp, not sure of the number but I will look it up. The 2 band uses a single op-amp - LM4250.

If you can wield a soldering iron I am sure that it will be a relatively easy fix.

I didn't know that MM did a Sterling SUB, I thought it was just a SUB but the 2 and 3 band preamps are pretty standard, the only exception is the 3 band with the phantom coil, as in the SR5, from memory these have a dual plus a quad opamp.

fred

[bassman]

The Sterling SUBS are kind of rare. Actually, I think all of the SUBS are rare, and I also think that they are a real deal on the used market.
Most can be had for $400 to $450 which is a steal for a USA made Musicman bass. I don't care that the bodies are made of poplar, I like the tone of these basses more than the high end MM basses.

Sterling Ball (Big Poppa on the MM site) said that he should have put a $100 bill under the pickup on each SUB he made.
Obviously, he doesn't view the SUBS as a good profit center for MM, so they stopped making them.

I really wnat to get this bass going again. I stopped by Radio Shack to see if I could buy the OP amp but they don't have the right one.
I did buy a 8 pin IC socket that I am going to put on the circuit board of my SUB Sterling bass.

I know I still have to post pics but I am doing this from work and I don't have any pictures of this bass on Photobucket.
That will change as I get the time to take some pictures.

[bassman]

I called Music Man and ordered a new chip for my bass. I know that they (TL062CP) should be available on the cheap but Radio Shack doesn't have it and after shipping charges and etc, I just ordered it from Music Man for 7 bucks and I will take my chances on putting it in.

They also said that they would sell me a new preamp for $75 if I returned the one out of my bass. That is a fair offer, but I want to see if I can fix this sucker.

I guess I am a glutton for punishment.

[Ken Baker]

Don't forget that you can (maybe should) solder a socket to the board then simply plug the new IC (chip) into it. This would protect the IC from excessive heat from the soldering iron and make any future replacements easy. You'd need an 8 pin DIP socket for printed circuit board (PCB) use, which may be available to Radio Shack. You orient it on the board just as if it were the IC itself.

Example:



Ken...

[bassman]

A socket installation is definitely going to happen to this bass. I did pick up a socket at
Radio Shack. The kid who worked there didn't know what an IC was or what an IC socket was. I found it myself by looking through their stock. LOL

I would like to protect this new chip form another dumb- ass move like reversing the battery, but I am not sure that I understand Deltafred's explanation of how to install a protection diode on the bass.

I will re-read his posts on the subject.

Thanks,
Bill

[deltafred]

Bill

Rather than try and explain how to do it I thought the best thing was a photo so I added a diode my 2 band EQ only to remember yours is a 3 band. Unfortunately my SR5 3 band is completely different.

I did however find a very interesting site http://www.musicmanbass.org/mycustompage0019.htm that has all things MusicMan Bass on it. If you look on the linked page, almost at the bottom for the is the 3 band EQ part. If yours is Oct 2006 onwards as in the penultimate photo then it already has a protection diode on the board, the black cylindrical component to the left and down from the IC. If it is the one above that (before Oct 2006) then it does not.

If you need to add one then probably the easiest place to put it is on the jack socket tags. It should go with the banded end to the red lead that goes to the PC board, the plain end to the black (ground, screen, battery negative) leads that goes to the battery, bridge and PC board. I would use a 1N4001 (or 1N4002,through 1N4007).

fred

[bassman]

Fred,
My TL062 chip arrived from Musicman with a couple Musicman and Ernie Ball stickers just for fun.
The chip is in its own protective carrier, rather neatly packaged for use when i need it.

I appreciate you attempt to direct me to the protective circuit for my 3 band pre-amp. I am assuming that my bass doesn't have it since the chip was fried in the first place. I will look over the circuit again and see where to place this component to get that protection.

I talked to a tech who just fixed my portable GK 200MB amp. He said that I should get some " wick" to remove the solder holding the old chip to the circuit board and to be very careful with the traces on the board. I intend to do just that.
I am going to start on this tonight.

I will take some pictures and post them.

[deltafred]

I talked to a tech who just fixed my portable GK 200MB amp. He said that I should get some " wick" to remove the solder holding the old chip to the circuit board and to be very careful with the traces on the board. I intend to do just that.
I am going to start on this tonight.

Bill

I would cut the legs off the chip first with a small pair of cutters, then you can use solder wick to remove the individual pins. This way there is less chance of damaging the tracks.

fred

[bassman]

I wish I had read your last post before diving in. I am too angry to take pictures.
I heated up the chip and pried it off of the circuit board but I was removing what I thought was a broken pin from the chip and extra solder and a piece of the trace came up off of the board. ARRGGHHH!!!

I may be dead in the water. I went ahead and attached the socket ,soldered it in place and then put in the new chip. Attached a battery , plugged her in to an a mp and did a quick test- No sound coming from the bass.

I may have to call it quits and order a new preamp from Music Man for $75 and a trade in of the old one.
Anyway- Here is a sample of a jam i played at last weekend.

[YouTube]http://www.youtube.com/watch?v=7xWUX07w5p4&NR=1[/YouTube]