Gainclone Fun - flames and more Help

[jawbreak]

Well I finished my first gainclone based on brains kit.

One speaker has offset of 14.5mV while the other is reading a
-91.5mV

I put two 10ohm resisters across the speaker terminals and a 22k across the input and still read same results.

Next I hooked up a speaker to the 14.5mV one and cd player to input. I went through a preamp first and no sound or nothing. Then I tired pluging the cd player directly into the amp and when I powered on the resister across the -91.5mV speaker terminal immediately bursted into flames. Still got no sound out of the speaker not even a hiss or hum or anything. The speaker is has 8ohm impedence.

Any suggestions on what to do now?

 

[Stocker]

*bump*

Interesting. I suggest not listening very closely to the next 10R resistor...?

What was the power rating of the defunct component?

 

[wigginjs]

Well, I haven't actually built one myself, but my recommendation would be to go over all of your connections and double check your component placement.

 

[digi01]

my recommendation would be careful to check all ground wires.

 

[jawbreak]

*bump*

Interesting. I suggest not listening very closely to the next 10R resistor...?

What was the power rating of the defunct component?

Well the resistor was one of those cheap radioshack ones. It didnt burst into flames til I didnt use a preamp before the amp which seems interesting.

Im going to have to rewire this whole thing again I suspect.

 

[Stocker]

I meant, was it a 1/4W-sized, 1/8W power-rated cheapie, good for < only the 0.9 /10 = .09 * .9 = .081W that went through it?

Try a higher power resistor.

 

[jawbreak]

It was 1/4 Watt Carbon-Film resistor.

Does this seem correct.

For grounding I have bolt in the case with the middle prong from wall outlet and a wire from each amp board from the CHG. Is there anything else that should be grounded?

Also in wall socket does it matter which prong you hook the primaries of the transformer to? I have the hot connected to the left one and the neutral to the right. It seems ok as im getting like 30 something volts after the rectifier.

All wires seem to match up from the rectifier to the amp.

Could it be the chips are bad, I could of messed them up somehow maybe.

hmmmm....

 

[jeff mai]

It didnt burst into flames til I didnt use a preamp before the amp which seems interesting.

Sounds like an oscillation. With the input flapping around this can happen. If you don't have something attached to the input while testing, you should ground it with an alligator clip or a shorting plug.

 

[Stocker]

You said they do fine into speakers, which makes me suspect the actual power handling ability of the resistor. Since you popped the resistor at turn-on, I also suspect a turn-on thump. Put a volt or three across the resistor and what happens? Do you get a turn-on thump with a speaker hooked up the same way the resistor was hooked up when it fried?

Some 1/4W sized resistors are good for 1/8W or less...

 

[jawbreak]

I only hooked up one speaker to the side with the 14mV offset and put the resistor across the -91mV just to see if the one channel was working ok. When the resistor blew and any other time no sound or anything came out of the one speaker.

As far was bridging the input, i put a resistor across it. Is this right? I also trying cd -> passive preamp -> amp and cd -> amp , which is when the resistor blew.

When a cd is playing the output on the speaker terminals is constantally changing but Im getting no sound. Maybe a bad speaker? Brand new never used it on anything before.

Thanks for the replies, I really appreciate it.

 

[Stocker]

test the speaker with something else.