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Originally Posted by upnorthpaul  The active portion of the electronics made loud buzzing sounds for awhile, then quit completely. Could this just be the chip or the whole module board? The passive works fine. Are there new modules available? This is a single pickup 1505, serial number CL09386. Thanks for your input. |
The chip is the most likely suspect here, as the passive components seldom fail. Take a look at the chip...you will probably find an LM4250 or LF441. Either of these should be available at a fairly low cost from Digikey. Many local electronics parts houses will carry a "generic" replacement for LM4250 numbered as NTE944. Should you go to buy one of those, ask to see the part first, as NTE944 is available in a couple of different physical packages- you want the 8-pin DIP. If you are in a pinch, LM741, available at most Radio Shack locations for around a buck, will work in the circuit. LM741 is an older part than the other two and has inferior specs but I have used one and there was little, if any increase in noise. Also, TI makes a LM4250 replacement numbered OPA704PA.
When you do the replacement, make sure that the preamp is not under power by removing the battery. Should you encounter a chip numbered with anything that I have not mentioned, let me know the part number and I'll tell you where to find one.
