little gem question

[thomas2]

hi.. i forgot the amp on for a few hours yesterday (i was using a ibanez pedal adapter) and now i think the amp seems to be kinda quiet.. i don't know what could have happened, but i can't get it to distort anymore without using a booster pedal.. the volume level used to be way too loud for full volume playing in my apartment before.. so.. did i break the amp or what?  :lol:

[thomas2]

is it possible that a dod 250 preamp's output was too high for the amp?

[B Tremblay]

How many volts does the adapter put out?

[thomas2]

i've used the same adapter before.. it's a standard 9V DC adapter

[petemoore]

It is quite possible to overheat the chip, especially if there's no heat sink.
 Not to say this is absolutely it, but I'd stick another new chip in it and see how it performs.
 Could be a bad cap,I think less likely.
 Let me kn ow if you'[d like to put in a Q&D heat sink, these guys have designs for them too.

[thomas2]

heat sink would be nice.. i've never even thought about it before..  :shock:  unfortunately the chip was my last one.. gotta wait until i get more of them

[thomas2]

besides being broken.. i really like this amp.. kinda like brian may's deacy amp.. small, shitty, ugly, but just the right one for my purposes  :twisted:

[spongebob]

Does the chip get warm after you have turned on the power for a few minutes? If you have another lm386 you could replace it and see if it's the chip or something else... maybe one of the electrolytic caps has failed...

[thomas2]

thanks for replying.. i will check the chip out..

[B Tremblay]

i've used the same adapter before.. it's a standard 9V DC adapter

Are you certain that it actually puts out 9v?  I have an unregulated 9v adapters that measure 14v!  Is the 386 that you're using rated for higher voltages?

[thomas2]

i am.. i checked it with my multimeter

[petemoore]

Slow ramp/heat checks.
 I turned the vol to a meduim setting, and played through it for a few minutes, checkin the heat buildup every 30 seconds or so...cool..
 Turned it up a bit, [adding Fuzz...whatever], and played it a bit, and noticed warmth at the chip, which began ramping [getting hotter] as I continued to play for a minute.
 Then I hooked on a sheet of copper, about 2'',...With 'fins' cut and bent from the sheet so air could 'get around' and cool better...I soldered a wire to the sheet, and drilled a hole, so I could have the chip under the sheet, wire under the chip as a strap then through the hole and then hooked over the end of the sheet so I could 'bend a little and get clamping of the sheet to the chip..super glued...this dissipated chip heat effectively enough to get much more output without thermal failure type temperatures.

[thomas2]

thanks man!! maybe the adapter didn't have anything to do with this.. i also played with some boosters.. and i mean.. they boost alot!! maybe that fried the chip.. thanks for the advice.. gotta make one and see
:lol: