I need help with a Hiwatt amp

[Gonzalizimio]

Hey there guys.

I have a small Hiwatt Maxwatt G15/8 combo that went completely silent. When I turn it on the led is on but no sound comes from it. Do you want me to post an image of what it looks like on the inside or can you give me any tips on how to detect the problem?

Thanks, Dagur

[52 Bill]

I have a small Hiwatt Maxwatt G15/8 combo that went completely silent. When I turn it on the led is on but no sound comes from it.

Welcome to the place. The two things that you should check are the headphone jack and the speaker. The headphone jack has a switch contact that shuts off the speaker. If it get dirty the speaker will shut off even with no headphone plugged in. If you plug in a set of headphones, does the sound come through the headphones?

[Gonzalizimio]

Welcome to the place. The two things that you should check are the headphone jack and the speaker. The headphone jack has a switch contact that shuts off the speaker. If it get dirty the speaker will shut off even with no headphone plugged in. If you plug in a set of headphones, does the sound come through the headphones?

Thanks for the reply, but this seems not to be the problem.

[J M Fahey]

Sorry but

this seems not to be the problem.

doesn't help us much.
Did you check the speaker?
At turn on or off, does the speaker make *any* sound? (Pop/click/thump)?
When On, with your ear by the grille, can you hear at least a slight hiss or hum, which disappears with the amp off?
With the speaker disconnected from the amp, touching positive and negative to a battery's positive and negative terminals should produce a pop on the speaker. Does it?

[Gonzalizimio]

Sorry for the lack of information.
I turned that guy on with my ear by the grills and I heard the slightest hum. I also did that thing with the battery and it made a pop. So the speaker itself should be okay.
What do you think I should do next?
Thanks again a lot for your tips guys, I appreciate it a lot!

Edit: It has an aux-in on the back. I plugged a RCA to it and played music through it and no sound came.

[Gonzalizimio]

Additional information:
~240V/50Hz 40W / [fuse symbol] T0.5AL 250V

Pics:

[DrGonz78]

Do you have a multimeter w/ a setting to measure DC volts? If so you should check to see if there is DC on you speaker terminals that come out of the amp and make sure your output transistor(s) are not blown. Although the sound of DC on the speaker would be a noticeable hum and not just a tiny hiss... But still would be nice to know if the amp is safe to hook up to your speaker.

[J M Fahey]

Connect an MP3 player , CD player or something to the CD input.
Do you get sound?

Take a closeup picture of the power amp chip (the one that's bolted to the metal bracket)where the pins are clearly seen, to suggest you some voltage readings.

Take another closeup of the 8 pin rectangular integrated circuit6, also showing pins clearly.
On one end of its plastic case there is a notch or a small hole, to show which side it's pointing to.
Illuminate as to it being visible on the picture, so you can identify legs, also for measurement.

[Gonzalizimio]

I do not have a multimeter, sorry about that. If this problem continues I will get one borrowed.
I checked the fuse in the power input, it was all right.
I did connect my computer to the CD input, got no sound.

I took pics, but it's really hard to reach every part to get the best shots, but here's what I got:

http://i46.tinypic.com/260x2mq.jpg
http://i46.tinypic.com/24bua35.jpg
http://i49.tinypic.com/6zwtqa.jpg
http://i50.tinypic.com/1z3zbk4.jpg

[J M Fahey]

Good, that will do.
Bring the owner together with the multimeter, so he can properly set read it.
He should also have practice on removing (safely) components from a PCB and replacing them properly.

[DrGonz78]

Definitely would be nice to see if there is correct DC voltage going to that 4558 IC chip, so a multimeter is important here. Also, need it to check voltage on the power amp chip.

Sometimes these practice amps have trouble w/ the pots (volume pot) and they crack or break. That will stop the amp from passing signals and you will hear a faint hiss but never the audio signal. Do you have any tools like a soldering iron?