Faulty HH Electronics MXA100

[Uriel]

Hi all.

Something's gone wrong with my beloved amp!

I seem to have lost some of the output from one channel only. Now, this may be technically incorrect, so I'll describe exactly what happens.

I'm listening to "Dead End Friends" by Them Crooked Vultures. The tune starts, and I can hear everything properly (as best as I can tell). Ten seconds into the tune, all the instruments stop apart from one guitar on the right. It plays 2 bars, then the rest of the band join in. My problem is that I cannot hear those 2 bars. When the rest of the band starts up again, I can hear from both channels.

I've just tried a similar test with "You're Wondering Now" by The Specials. At the start of the track, people are banging on two doors, one on the left and one on the right. The one on the right is audible, but nowhere near as loud as it should be.

I am playing the tunes on an MP3 player. I have played them out of the headphone socket and also via a LOD cable, and I get the same thing happening each time. When tested directly out of the MP3 player, through headphones only, or via the LOD cable, through a headphone amp and then out the headphones, all works properly. If I plug the MP3 player into a different amp, it all works fine.

The problem with the HH amp isn't with the speaker output sockets or speaker cables. I still get sound from both speakers, but the right hand channel isn't outputting everything it should, or maybe it's just not kicking out as much volume as it should. (It's just occurred to me that I don't know if there's any crossover between the output channels, or how much there might be if there is.) I have swapped speaker cables to check them, to no avail. If I plug in a pair of headphones, I get the same problem with the right hand channel through the cans.

I have tried swapping input channels, and input cables, again to no avail.

Any ideas? And does anyone have a circuit diagram?

[sakis]

tap the amp with your hand ....or even better pop the hutch and tap with a plastic tool the output relay .....Do not do that if you have no experience on safety procedures ....

if the problem is the relay taping it will make it active for a second or so make the problem better or worst ....

Taping on the amplifier boards though might also be a fault finding procedure but be careful cause if your amp has serious soldering issues and you tap on it might cause serious trouble or even blow the amp .

so ...
#1 tap the relay ...
#2 if this doesn't help you need to check soldering this will require skills and some experience....
#3 you also need to sample capacitors from the amplifier board to make sure if working properly or have leaks..that will also require skills and some experience....

seek for expert help if you think that you cannot do the above

kind regards
sakis

[Uriel]

Oh, I'm a total noob with regard to anything electrical. Expert help shall be sought...

[hardwareguy]

Originally Posted by Uriel

Oh, I'm a total noob with regard to anything electrical. Expert help shall be sought...

Even if you choose to have the amp worked on by a shop, I'd suggest getting some very basic background in electric stuff.

Lessons In Electric Circuits -- Volume I (DC) - Table of Contents
Read chapters one through three at least...and pay very close attention to ch3, the safety section!

[jitter]

Originally Posted by Uriel

(It's just occurred to me that I don't know if there's any crossover between the output channels, or how much there might be if there is.)

By this you mean "balance"?
Worth checking to see if it's still in the middle position.

[Uriel]

Originally Posted by jitter

By this you mean "balance"?
Worth checking to see if it's still in the middle position.

No, there's no balance control. Perhaps crossover's the wrong term; I'm talking about when, say, 5% of the left channel comes out of the right and vice versa. I know headphones are wired up that way but dunno if amps are the same.

[ingenieus]

Originally Posted by hardwareguy

Even if you choose to have the amp worked on by a shop, I'd suggest getting some very basic background in electric stuff.

Lessons In Electric Circuits -- Volume I (DC) - Table of Contents

Thanks for the link.

For other members: there are five more volumes in the series, available at
Lessons In Electric Circuits