Peavey Deuce VT Series Effects Channel Distortion Troubleshooting Help

[jasonguitar]

Didn't Peavey make a little PCB that could be wired in to take the place of the TL604 ?

I called Peavey and those TL604 adapter kits are long discontinued. All the info to make one is available though. See attached file.

[jasonguitar]

I'll take a whack at building an adapter from the info on the sheet. About $22 parts with tax and shipping from Newark.

[g1]

I'm really curious what kind of fake these could be. With something like power transistors I can totally see that someone would put an undersized die into a big package, and it still works as a xxx transistor or whatever but can't handle the voltage or current the real part would. On something ilke this, though, if it is actually a functional die is there a chance that it will work fine? Also, I don't even know how the intellectual property rights work for parts like these. If I look at the datasheet for an LM741 from different vendors there is no details of who owns that spec. Can anyone make a 741? I have no idea.

My guess is maybe the op amp section would work, but not the switch, etc.. But that is pure speculation.
As far as the part numbers, using your example. 741 would be a generic number. LM would be manufacturer specific (National if memory serves). Or say TL072, TL was a Texas Instruments part. I recall seeing other '072' chips that came out later, but they were not TI parts so did not have the TL prefix.

With the fake knock-offs, we almost always see an original manufacturer prefix, and also often a date code from the time they were actually being made. So that would mean there are stockpiles of the original parts in China, yet the parts are obsolete. That is just not true. And you will see the same date codes over and over in photos from all kinds of sellers.
To further complicate things, the fakes are now being warehoused here and sold online. So you can't just avoid parts shipped from China anymore to be safe, they can be fakes warehoused here.

[glebert]

This is mostly philosophical, but since we probably have a few weeks to wait before results...

I think we all agree that if it has the TI logo and is new from China it is a fake part, but it is possible the only faking is the attribution. If it was actually a functional part and it just said 604 on the top and was called an analog CMOS switch with the same pinout as the TL604 it wouldn't be a fake anymore. Kind of like anyone can make blue jeans but if you put a Levi tag on them they become fake Levis, but they still are blue jeans. There are other CMOS switches out there, it really would not be that hard to make a part that did what the TL604 does, even reusing a die and changing pinout. This gets into my previous question of IP and if there is someone who owns a 604 spec that would be able to sue and (try to) stop someone else from making that part.

[g1]

If it was actually a functional part and it just said 604 on the top and was called an analog CMOS switch with the same pinout as the TL604 it wouldn't be a fake anymore.

True. But there are legit chip makers in China, so why not just make it a real part with a legit number. You wouldn't even need to call it a 604, just say it's a sub for 604 and it would quickly catch on.
They aren't even going for NOS bucks so why bother faking it?

[glebert]

They aren't even going for NOS bucks so why bother faking it?

That is the 5 for $10 (shipped) question. Then again I can't even pretend to understand how Chinese manufacturers are making any money. Sometimes I think they do stuff just to keep the workers busy. Or maybe these actually have listening devices that connect to PRC headquarters so they can steal our classic rock secrets.

[Enzo]

Well don't look at it like it is a China Inc deal. There are dishonest people here just as there are in China. I don't see a China company deciding to manufacture fake TL604 chips. I see a couple guys who can buy surplus or defective or off spec parts from somewhere, and all they need is a chip printer to label them. A few thousand ICs they bought for next to nothing now say TL604 on them, and they sell them to us dupes.

Imagine AC-Delco makes millions of spark plugs, and a batch here or there fails in some manner. Materials will crack under heat, or the spark doesn't strike reliably, whatever. They could just send them to a land fill. And I could go retrieve them and sell them AC didn't make bogus parts, I did..in a sense. In this world it is more likely they sent the bad bins full to a recycler who bought them for real cheap hoping to profit by extracting the iridium or whatever is in the metals. That recycler could in turn sell them to me at a small profit, and I could sell the bogus parts.

In fake parts, the fake-ness isn't that it takes a poor TL604 and labels it as a TI product, the fakeness is that the part isn't what it is supposed to be AT ALL.

If you buy some fake 2SD424 transistors in TO3, and cut them open to find tiny dies that couldn't possibly meet spec, nobody made fake 2SD424. Someone found a real cheap price on a lot of some smaller spec transistor, like one meant for a small power supply or something, and they then printed 2SD424 on them. Making them appear to be a much more valuable type than whatever it was at birth.

A friend of mine worked at a manufacturer of higher end gear and they wanted 12AX7s that were absolutely balanced and noise free. They bought 12AX7s from Sovtek by the 10,000 and tested each one. The ones that were uneven or not noiseless they THREW OUT. My pal was free to save as many as he liked from the dumpster. He sent me a box of 100; Nice gift. They may not meet the demanding spec of that OEM, but they were perfectly fine in guitar amps. Another friend of mine worked somewhere that tested small signal transistors for matching and noise. Likewaise he got as many rejects as he wanted for free. And I got a few bags myself. I could have gone to one pof those OEMs or any of a thousand others, and offered to take their reject stock at deeply discounted rates. And I could then label them as I saw fit to sell to dues online. But I have more ethics than that. Point is there are tons and tons of parts that can be had for next to nothing, or in some case for exactly nothing. THOSE parts are what are sold as fakes.

If I sell you and IC as a TL604 or as a functional equivalent of a TL604, if the thing does not perform as one, then it is still a fake.