SoundMods wrote:
Speaking of a DIY guy with time on his hands.
Tom's offer is very generous and he has many DIY scratch-build projects under his belt. You could learn a lot in a very short time.
Especially soldering small devices. You can easily "heat-fry" an op-amp if not careful. Walt:
An interesting story on Op Amps that happened yesterday . When testing the board at David's we started with the right channel and noticed a problem including a 2 volt DC offset. I though I detected some heat so I very quickly touched one of the Op Amps and promptly burned my finger so badly I had a blister. I immediately turned the power off and checked the board. In my haste to get the power supply connected I had reversed the plus and minus wires to that channel. The power supply is one I have laying around that is quick and dirty with 78 and 79 series regulators. The regulators sensed the excessive current and went into limiting preventing damage to the PS. The wiring to the left channel was OK so we tested that channel after removing the Op Amps in the right channel and fixing the polarity so we did not blow up the bypass tanatalums.
The left channel worked fine. After the tests, just for grins I put the cooked Op Amps that were now cooled down back in the right channel and both David and I were shocked to find that they both worked perfectly. We could not believe our eyes. It was amazing that an IC so hot that it could raise a blister on your finger with just a quick touch could still work after cooling down. Of course both amps went into the trash because I would not trust something that had been that hot. Although the reverse voltage was limited on the bypass tantalums I replaced those as well for dependability reasons. The bottom line is that I would have put down a large sum of money that the amps would have to be total trash but they were not. Will wonders never cease. The take away from all this is check your wiring several times before plugging things in. When you rush bad things happen. This from your bonehead friend Tom. You would think I would know better after so many years.