[Fusky]

So this Beautiful Akai Am-u02 amplifier I own has a bit of a problem !!!
So when you turn this amp on the first thing you notice is that the red clipping light comes on and when audio is played though it the left channel is practically silent. If you turn the amp up far enough you will hear a distorted sound with some missing frequency coming though the left channel it is the music but is heavily broken up and sounds horrible.

So far i have tested the the pre amp just running it into the aux of my akai am-u01 and it works like a charm in that sense and sounds absolutely amazing. I have also tried a seperate amp as a pre amp into this amp and the same issue.

I have tested all fuses with a multi-meter and all of the come in at 0 ohms and perfect connection. I have also removed the fuses but still the red clipping light shows up.

I now have the amplifier open and i have looked over the entire board and nothing seems to be burned there is also no burnt smell in it.

I know half decently what im doing but cant crack this one on my own. I greatly appreciate all responses and all possibilitys and hope someone can help me :laugh:

This video is just to get a better idea of what im talking about So this Beautiful Akai Am-u02 amplifier I own has a bit of a problem !!!
So when you turn this amp on the first thing you notice is that the red clipping light comes on and when audio is played though it the left channel is practically silent. If you turn the amp up far enough you will hear a distorted sound with some missing frequency coming though the left channel it is the music but is heavily broken up and sounds horrible.

So far i have tested the the pre amp just running it into the aux of my akai am-u01 and it works like a charm in that sense and sounds absolutely amazing. I have also tried a seperate amp as a pre amp into this amp and the same issue.

I have tested all fuses with a multi-meter and all of the come in at 0 ohms and perfect connection. I have also removed the fuses but still the red clipping light shows up.

I now have the amplifier open and i have looked over the entire board and nothing seems to be burned there is also no burnt smell in it.

I know half decently what im doing but cant crack this one on my own. I greatly appreciate all responses and all possibilitys and hope someone can help me :laugh:

This video is just to get a better idea of what im talking about youtube.com/watch?v=MHDrVWeBRrM

 

[Fusky]

Anyone have any ideas all take anything to help me get this thing fixed!

 

[kijla]

Anyone have any ideas all take anything to help me get this thing fixed!

I have a similar problem with my AKAI AM-U02 did you manage to solve the problem with yours by any chance?

Thanks!

 

[Russellkendall]

So this Beautiful Akai Am-u02 amplifier I own has a bit of a problem !!!
So when you turn this amp on the first thing you notice is that the red clipping light comes on and when audio is played though it the left channel is practically silent. If you turn the amp up far enough you will hear a distorted sound with some missing frequency coming though the left channel it is the music but is heavily broken up and sounds horrible.

So far i have tested the the pre amp just running it into the aux of my akai am-u01 and it works like a charm in that sense and sounds absolutely amazing. I have also tried a seperate amp as a pre amp into this amp and the same issue.

I have tested all fuses with a multi-meter and all of the come in at 0 ohms and perfect connection. I have also removed the fuses but still the red clipping light shows up.

I now have the amplifier open and i have looked over the entire board and nothing seems to be burned there is also no burnt smell in it.

I know half decently what im doing but cant crack this one on my own. I greatly appreciate all responses and all possibilitys and hope someone can help me :laugh:

This video is just to get a better idea of what im talking about So this Beautiful Akai Am-u02 amplifier I own has a bit of a problem !!!
So when you turn this amp on the first thing you notice is that the red clipping light comes on and when audio is played though it the left channel is practically silent. If you turn the amp up far enough you will hear a distorted sound with some missing frequency coming though the left channel it is the music but is heavily broken up and sounds horrible.

So far i have tested the the pre amp just running it into the aux of my akai am-u01 and it works like a charm in that sense and sounds absolutely amazing. I have also tried a seperate amp as a pre amp into this amp and the same issue.

I have tested all fuses with a multi-meter and all of the come in at 0 ohms and perfect connection. I have also removed the fuses but still the red clipping light shows up.

I now have the amplifier open and i have looked over the entire board and nothing seems to be burned there is also no burnt smell in it.

I know half decently what im doing but cant crack this one on my own. I greatly appreciate all responses and all possibilitys and hope someone can help me :laugh:

This video is just to get a better idea of what im talking about youtube.com/watch?v=MHDrVWeBRrM

I have the same problem. Any idea what the fix should be.
Russell

 

[markybran]

hi .
i have the same amp and the same problem . ive checked all voltages on the stk 3042.. all in order , so i decided to replace the 4 large 6800uf capacitors ,but before i did i swapped the 2 darlington stk 0030s around and out went the clipping light ,i left it switched on for over 24hrs with no problems ... great fixed (maybe a dry joint ) decided to replace caps anyway having bought them ,so working great for about a week , then recently back came the clipping light .
so having only disturbed the darlingtons im wondering if one is breaking down intermittently all i can find is one has a slightly larger voltage on one pin . ive posted my experiece as it may give some pointers to help anyone else .....work in progress.....ill keep you posted

mark

 

[oavramescu]

hi .
i have the same amp and the same problem . ive checked all voltages on the stk 3042.. all in order , so i decided to replace the 4 large 6800uf capacitors ,but before i did i swapped the 2 darlington stk 0030s around and out went the clipping light ,i left it switched on for over 24hrs with no problems ... great fixed (maybe a dry joint ) decided to replace caps anyway having bought them ,so working great for about a week , then recently back came the clipping light .
so having only disturbed the darlingtons im wondering if one is breaking down intermittently all i can find is one has a slightly larger voltage on one pin . ive posted my experiece as it may give some pointers to help anyone else .....work in progress.....ill keep you posted

mark

Hi,
I have the same problem with one Akai AM-U04... I have bought it one month ago (SH) and last week when I started it, after some seconds of listening music at low level it was a big noise in the speakers and lighted the clipping led. Then the level bar of left channel remained at max level. And no music... If I restart the amplifier, the same happens after some seconds of music. I have tried to use some headphones and it happens the same. Some ideas?

 

[markybran]

Hi,
I have the same problem with one Akai AM-U04... I have bought it one month ago (SH) and last week when I started it, after some seconds of listening music at low level it was a big noise in the speakers and lighted the clipping led. Then the level bar of left channel remained at max level. And no music... If I restart the amplifier, the same happens after some seconds of music. I have tried to use some headphones and it happens the same. Some ideas?

 

[markybran]

Hi

Hi,
I have the same problem with one Akai AM-U04... I have bought it one month ago (SH) and last week when I started it, after some seconds of listening music at low level it was a big noise in the speakers and lighted the clipping led. Then the level bar of left channel remained at max level. And no music... If I restart the amplifier, the same happens after some seconds of music. I have tried to use some headphones and it happens the same. Some ideas?

Hi
Sound like something going open circuit on the input swap L /R inputs around and see if it happens on the opposite channel .is it the same on other source inputs phono aux etc.
Reserch suggests these type of amps suffer with the stk modules failing .another option is a re-cap they do dry out and go flakey they are 40 years old . Im still tracing mine down all voltages are ok on the modules and the amp is trying to do its job on the clipped channel so i will try replacing the capacitors and take it from there . I will keep posted on my progress as it may help others
Mark

 

[markybran]

update ......been at it 6 hours swapped a few caps out and around ,no joy tested a few transistors all meter out ok notice a 1.25a fused had gone ...replaced ... no better still going distorted on left channel after warming up for 4-5 mins. i give up for the night . fresh head tomorrow i think ... anyway the next day i was having a poke around with a wet finger (I KNOW) accidently touched one of the capacitors i handnt changed... hey left channel came clear iron came out and bingo.. so far so good .second time ive chased a dry joint . so anyone else having similar problems start with the cheapest option and go round the board checking the solder joints first ....