Genius SP-HF1250X - 2.0 speakers

[bocca]

Re: Genius SP-HF1250X - 2.0 speakers

I do have visual access, but my speakers are at my home, and I'm at work, so I'll do all that when I'm back home!

[ben7]

Re: Genius SP-HF1250X - 2.0 speakers

I do have visual access, but my speakers are at my home, and I'm at work, so I'll do all that when I'm back home!

Ok!

[999999999]

Re: Genius SP-HF1250X - 2.0 speakers

Measure the voltage at the V+/V- pins and ground for the LM4558 as Ben7 suggested. If it is not so high as to damage the opamp, then replace the two large caps right after the diodes. If it is too high and damaged the opamp, replace that too.

[bocca]

Re: Genius SP-HF1250X - 2.0 speakers

Hi ben7.

OK, i plugged it in again, and watched the speaker cone. It doesn't suck in, nor does it push out. It starts vibrating immideately, first small vibrations, for a second, and then with, i guess, full power.

Measured what you told me. Upper black contact measures 0.48, and lower is at zero. Multimeteris set to 20V

edit: that was with the speakers turned off. When I turned them on, voltage on the upper is about 9.27 (it's variable, but around that value), and on the lower is constant -0.7. Multimeter is again, on the 20V setting.

Those black circles are legs of the two caps (100 uf, 25v).

I am looking for the 4558 datasheet so i'll know where are v+ and v- legs. Then i'll do the reading

[bocca]

Re: Genius SP-HF1250X - 2.0 speakers

OK, so here's the datasheet:

http://html.alldatasheet.com/html-pd.../1/LM4558.html

What should I measure? And should i do it with the speakers powered on?

[Evil Lurker]

Re: Genius SP-HF1250X - 2.0 speakers

I see NP on the electrolytics... are those nonpolarized caps?

[budm]

Re: Genius SP-HF1250X - 2.0 speakers

Pin 4 is B-, pin 8 is B+ on the OP-AMP. You put the black probe of the meter to the DC ground (you can use the RCA input jack outer body for ground, the red will be used fro checking the voltage with speaker on.

[ben7]

Re: Genius SP-HF1250X - 2.0 speakers

Hi ben7.

OK, i plugged it in again, and watched the speaker cone. It doesn't suck in, nor does it push out. It starts vibrating immideately, first small vibrations, for a second, and then with, i guess, full power.

Measured what you told me. Upper black contact measures 0.48, and lower is at zero. Multimeteris set to 20V

edit: that was with the speakers turned off. When I turned them on, voltage on the upper is about 9.27 (it's variable, but around that value), and on the lower is constant -0.7. Multimeter is again, on the 20V setting.

Those black circles are legs of the two caps (100 uf, 25v).

I am looking for the 4558 datasheet so i'll know where are v+ and v- legs. Then i'll do the reading

YAY, a problem! The lower should be just about the same voltage as the upper, but negative. So the lower one should be about -9v.
FYI: I traced the tracks, which was very easy due to the good pictures, and those are the + and - power rails for the opamp.

Can you please measure the resistance of R44 (its a 470 ohm resistor)?

[bocca]

Re: Genius SP-HF1250X - 2.0 speakers

will be done tonight people. Once again, you have big thank you for your patience!

[ben7]

Re: Genius SP-HF1250X - 2.0 speakers

will be done tonight people. Once again, you have big thank you for your patience!

Any success?