Melted Black Glue

[bone]

Mabe its to hide that they are ripping off someone else's circuit!

Tony.

[Ronsonic]

It's not just you, John. A lot of modern schematics give me headaches. It's clear that a lot of manufacturers will not pay the additional costs of producing schematics beyond what is needed to develop the board layout and build the thing. So we get seemingly random component designators that make no sense in either schematic or board layout, and drawings for each board instead of for the circuit with a designation for what is and isn't on the board. It's also fun when they show something going off to a ribbon cable with no hint as to which lead.

There's no pride in producing a well drawn schematic, it is only a cost to be controlled.

[Klugetone]

I once had the pleasure of being in a business that was very competitive but involved common circuitry that could be found in any op-amp cookbook or engineering examples on a datasheet. Very similar to the tube amp situation in this thread. Potted circuits were very common to cover up all the "secret" innovations that made one MFG better than the competition. Epoxy was the most common goop we used. However, the real reason we and all of the competition (yes, we looked) gooped things up was to hide the fact there was absolutely NOTHING new or innovative in the design short of a tweaked bias resistor or whatnot. Hard to hype the Mojo of that stuff if anyone could see what was really in there. Not suggesting that's the case here of course. Just sayin'

Peace
Dave

Just want to add that the company I mentioned above was not my own nor was the potting jazz my idea. I was just the hired help. Didn't like the feel of the whole thing and didn't hang around too long.

[trem]

I once had the pleasure of being in a business that was very competitive but involved common circuitry that could be found in any op-amp cookbook or engineering examples on a datasheet. Very similar to the tube amp situation in this thread. Potted circuits were very common to cover up all the "secret" innovations that made one MFG better than the competition. Epoxy was the most common goop we used. However, the real reason we and all of the competition (yes, we looked) gooped things up was to hide the fact there was absolutely NOTHING new or innovative in the design short of a tweaked bias resistor or whatnot. Hard to hype the Mojo of that stuff if anyone could see what was really in there. Not suggesting that's the case here of course. Just sayin'

Peace
Dave

That is definitely a consideration. It seems to me that a lot of amps these days have what can only be refereed to as perceived value. There are several players like John mayer, Joe Bonamassa, etc., that play 50-100 watt heads with a price tag in the $4,000.00 to $6,000.00 range. That is quite a bit of money for a tube guitar amp.
Some of that pricing is wrapped up in the mystique of the amp. You can charge a lot of money for a product when "experts" in that field say there is something special going on. I wish I had made twice as much money as I did, I would have accepted it gladly. But face it, if Two Rock made a 5E3 combo amp, it would cost way more than the "same" amp made by Sara Richter.....

[Steve Conner]

Snake oil!

On the bright side, it means that you and I can build amps that are better than Two Rocks and Dumbles, just by perceiving them to be better. Nobody else might believe us, but we only have to convince ourselves.

At the end of the day, they're all tube amps and they all probably sound pretty much the same, the rest is just hype.

[scooperman]

reasons to coat the circuitry include

a. atmospheric conditions, for example operation at high altitude
b. corrosion inhibition, for example marine electronics
c. high voltage arc elimination, or for guaranteed creepage/clearance/isolation specifications
d. reduce vibration and shock impacts to components
e. hide components from copycats
f. make repairs difficult

I make industrial stuff so I am sometimes required to have my pcbs conformally coated. But for most commercial stuff I think "a", "b", and "c" are not applicable. I would give serious though to potting discrete commercial designs for reason "d", but for surface mount I would risk making it without coating. Reason "e" is unfortunately a fact of life for commercial product manufacturers, if its a simple circuit to copy and it sells well, then somebody will copy it. Reason "f" is hard to justify, this is for manufacturers that do not intend to support the product...build it, ship it, sell it, no schematics, no parts, authorized service centers are told DNR do not repair. They don't care about what they sold, they only care about future sales.

[Enzo]

If the unit is do not repair, the OEM is not going to bother making it hard to work on. The issue is low price point...period. They are even less likely on these to add the labor and materials cost to goop them for that reason.

DO not repair means nothing more than "we won't pay warranty claims on these."


If you are a little mod shop selling dreams, I can se you wanting to hide your idea from some other little mod shop. But really, Fender/Marshall/Peavey are not in the slightest concerned that someone in a basement might copy something. Nor do they harbor the delusion that gooping an amp would stop industrial spies.


There is the old arcade game Pac Man. You could jumper a wire between two points on the circuit board and it would play faster. RUn the wires up to a switch on the panel, and the player can speed up at will. I knew a guy who made speed-up kits for Pac Man, and sold them. It was a plastic box full of epoxy with wires coming out. You connected the blue and orange wires to the circuit board. Then the red and green wires to the panel switch. Worked pretty well. He sent me a sample. I couldn;t help myself, and cracked the epoxy off. Sure enough, inside the epoxy was a red wire spliced to an orange one, and a blue wire spliced to a green one.

[R ski]

Years ago a snowmobile engine had an ignition box that crapped out, it was during the recession of 82, being unemployed I found the replacement module very expensive. It was potted for the reasons mentioned in the post on this thread.

I placed the dead module on top of the garage wood stove and carefully melted the compound off the module. Surprisingly the circuit consisted of a uni junction switch a diode some caps. Copied the circuitry, potted mine in paraffin wax and was on happy trails again.

You can peek, but you better be good at with circuits and troubleshooting if the clone doesn't work at first.