Nashville Op-Amp Change (Mod)

Robert Leaman · From: Murphy, North Carolina, USA

Originally, Peavey's NV1000 schematics show signal chain op-amps as 4560. Later, these were changed to OPA2604. I have no knowledge when that change was made. The best substitution for either 4560 or 2604 is a Burr-Brown op-amp OPA2134PA. This is an eight pin IC and has two separate identical op-amps (dual). Burr-Brown is owned by Texas Instruments. There are five op-amps on the preamp board and four op-amps on the controller board.

The five op-amps on the preamp board are primary steps in the signal chain. These five are the only necessary substitutions. The four on the controller board are late in the signal chain where the S/N ratio is not as critical as the preamp.

Preamp Board: U1, U2, U3, U4, & U5
Controller Board: U100, U102, U105, & U109

Be aware of the op-amp pin orientation. Incorrect insertion can destroy integrated circuit components.
..

Dick Sexton · From: Greenville, Ohio

Great info Bob. Where are you getting your chips?

I figure anyone that can put their socks on without some help, could be successful at putting in these chips. And shouldn't be afraid of doing it, if they want. I do understand the newest NV112s have the chips soldered to the circuit board. But even that is only a mild inconvenience for the determined.

A few pictures I've taken of my own installation...
Unseen in the pics, is the wrist static strap I used.

http://cid-594320d13092d8fb.photos.live.com/browse.aspx/112%20chip%20Install

Robert Leaman · From: Murphy, North Carolina, USA

I got my information directly from Peavey. My history includes electrical engineering design, circuit board design, and real time software.

For those interested, the best method to remove an IC that is soldered to a PC board is to cut the IC legs as close as is possible to the PC board. Of course, this renders the IC that is being removed to be useless. However, if the offending IC were to be useful, why is it being removed?

After the IC legs are cut and the module removed, the remaining metal bits can be removed from the PC board with a low wattage iron and a good solder sucker.

If the IC resides in a socket, then the solution is obvious. However, my experience shows that when IC's are installed in sockets, there is considerable contact galvanic noise that is eliminated with the soldering technique.

...

Robert Cook · From: Collierville,TN

I'm the last guy to crack open an amp, but I did the install of the chips in my NV1000 and it went off without a hitch. It took about 25 minutes and that was with me being as meticulous as possible. Really easy.
_________________
Left-handed Pedalmaster-10, Nashville 1000, Fender Twin, Goodrich

Jack Stoner · From: Kansas City, MO

Ken Fox and I have been pushing the 2134 change in the 1000's for about 6 months.

Ken Fox · From: Nashville GA USA

I think they are the best opamp for a guitar amp application I have ever heard. We now use them in our mods for:

N112 and N1000
N400
Vegas 400
Profex 2 and Bassfex

I never saw a stock N112 or a N1000 with OPA2604 chips, ever. If oyu have one it is likely form one of the 100's of kits we sold before switching to the OPA2134PA chips in our new kits.

I do not advise unsoldering and installing sockets unless you are well trained in the use of soldering equipment. You need a temperature controlled soldering station with the correct size tip, good quality solder and solder wick. I remove the chassis from the amp to do that properly. It takes a little time, patience and an experienced person to do that for sure. The small traces on the circuit board can be burned off easily with the wrong equipment and a lack of experience.

Not all people are adapt at even changing out a socketed chip. I have had folks not follow directions and bed the pins, put them in backwards, have pins hangiong outside the socket, break the socket out while trying to remove the chip, piggyback the opamps right on top of the old opamps and more!

As an old friend said, "This might not be the job for you if you can catch the house on fire while doing an oil change for your car"

Robert Leaman · From: Murphy, North Carolina, USA

Yes, Ken, I've seen all those errors mentioned in pc board assembly departments. PC board assembly is commonly called "stuffing". Until pc board assembly was converted to robotic equipment, assembly errors averaged about 10% regardless of education, discipline, and/or work pride. It is somewhat difficult to completely educate people without technical knowledge to the multitude of hazards with eletrical/electronic equipment. Anyone who follows described procedures in my post does so at their own risk. I am not responsible for actions that I do not completely control and I assume that you may have the same philosophy.

Furthermore, even with automated assembly/soldering equipment, errors occur. I know of two documented cases where Peavey Nashville 1000 amplifiers were shipped with bad/poor control board solder joints. Both units were repaired under warranty but this error is eliminated with correct solder machine calibration and correct flux preparation.

As always, shade tree mechanics beware. If it works, don't fix it.

..

Robert Leaman · From: Murphy, North Carolina, USA

Yes, Jack, I am certainly not intending to subvert your previous professional experience and past recommendations. I merely provided location information for the integrated circuit change.

..

Jack Stoner · From: Kansas City, MO

The instructions that Ken Fox sends out with his kits contain detailed locations of the 5 chips to be changed on the preamp board.

Just noting that we have already been through the preamp board chip replacement and what is changed out. Your post came across like this was something new that no one knew about.

Forum Index > Electronics		Next oldest topic :: Next newest topic

All times are GMT - 8 Hours	Jump to: