Hi,
I recently got my hand on two malfunctioning amplifiers, one American Audio V3000 and one t.amp TA3200 MKII.
I am not really an electrician but an audio engineer and a musician, but I am also a curious person and with some free time on my hands I decided to try repairing these two amplifiers. As one might have expected I have however run into some dead ends and is turning here to see if there´s someone who might be willing and able to help me out.
So, let´s start with the American audio V3000.
When I first got it it pulled the 16A fuse of my apartment as I tried to power it up (the amps internal fuse is a low fast blowing fuse of 20A).
The left amplifier element also got very warm very fast in the short time it was operting.
When opening it up and measuring the two amplifier channels I found that the left side amp measured oddly in the transistors with fully open circuits.
I took them off and found a few broken, open circuit, transistors. I ordered new ones and replaced both the fully open ones and any onces that would be measuring oddly in comparison to the new ones.
I also replaced a few ceramic resistors that measured fine but that had some minor cracks in them.
I ensembled it all again and now both amplifier elements were measuring mostly equal. No open circuits and only very minor differences in numbers, probably due to the older transistors on the right side.
I start it up again and at once the 16A fuse goes.
Measuring the pins connecting the elements to the power board both sides reads the same.
I also tried starting the amplifier up with the elements disconnected from the power board which also pulled the fuse (that might be natural though - in all honesty I don´t know but thought it might help identify if the issue is in the amp elements or the power board/supply).
I haven´t measured the caps on the power board yet, but they look fine and are really not at the age I´ve read caps usually might fail at.
Does anyone have any idea of what the issue might be or what to look for?
It kind of seems like a short circuit to me...
Schematics for the mentioned model can be found below:
View attachment v3000amp.pdf
View attachment v3000p.pdf
View attachment v3000pow.pdf
Now, for the t.amp TA3200 MKII
This one has 5 led´s for each channel reading "active, signal, signal, peak, fault".
Upon start up all five leds on the left side were lighting up and stayed lit.
The right side only had the "active" led light up permanantly, and the fault led light up for about 1-2 sec in the beginning, much like other amps where the led is labeled "protect" instead.
I opened up the amp and compared the right side element to the left side one.
Apart from the 32A on board fuse that this amplifier has it also has two 10A fuses on each amplifier board. One of these fuses were blown and a lot of transistors were either open or reading very odd on the left side (transistors of the same type as in the V3000 btw) so I replaced almost all of them.
After re-assembeling everything I started her up again and now both channels had only the green "active" led´s ligting up fully, along with the red "fault" for the first 1-2 sec. Everything seemed fine.
However, as I shut the amplifier down the "fault" led´s light up and stay lit for another 3-5min, even when the amp is turned off and the power plug disconnected. Even more odd do I find it that if I try to restart the amplifier withing the next 30min of just having had it on, it blows the fuse of my apartment again(16A) - but if I wait a bit longer, for about 30-40min it starts up again without blowing any fuses.
Could it be that it just has a very hard start up, give that its internal fuse is on 32A and my apartment just on 16A and that it´s actually fine? But in that case why doesn´t it do the same thing all the time and why are the "fault" led´s ligting up for 3-5min everytime it´s shut down.
No schematics on this one and I haven´t tried putting the amp to any speaker so far.
Any idea of what these symptoms might be an indicator of?
Thanks for any and all help!
Best,
J
I recently got my hand on two malfunctioning amplifiers, one American Audio V3000 and one t.amp TA3200 MKII.
I am not really an electrician but an audio engineer and a musician, but I am also a curious person and with some free time on my hands I decided to try repairing these two amplifiers. As one might have expected I have however run into some dead ends and is turning here to see if there´s someone who might be willing and able to help me out.
So, let´s start with the American audio V3000.
When I first got it it pulled the 16A fuse of my apartment as I tried to power it up (the amps internal fuse is a low fast blowing fuse of 20A).
The left amplifier element also got very warm very fast in the short time it was operting.
When opening it up and measuring the two amplifier channels I found that the left side amp measured oddly in the transistors with fully open circuits.
I took them off and found a few broken, open circuit, transistors. I ordered new ones and replaced both the fully open ones and any onces that would be measuring oddly in comparison to the new ones.
I also replaced a few ceramic resistors that measured fine but that had some minor cracks in them.
I ensembled it all again and now both amplifier elements were measuring mostly equal. No open circuits and only very minor differences in numbers, probably due to the older transistors on the right side.
I start it up again and at once the 16A fuse goes.
Measuring the pins connecting the elements to the power board both sides reads the same.
I also tried starting the amplifier up with the elements disconnected from the power board which also pulled the fuse (that might be natural though - in all honesty I don´t know but thought it might help identify if the issue is in the amp elements or the power board/supply).
I haven´t measured the caps on the power board yet, but they look fine and are really not at the age I´ve read caps usually might fail at.
Does anyone have any idea of what the issue might be or what to look for?
It kind of seems like a short circuit to me...
Schematics for the mentioned model can be found below:
View attachment v3000amp.pdf
View attachment v3000p.pdf
View attachment v3000pow.pdf
Now, for the t.amp TA3200 MKII
This one has 5 led´s for each channel reading "active, signal, signal, peak, fault".
Upon start up all five leds on the left side were lighting up and stayed lit.
The right side only had the "active" led light up permanantly, and the fault led light up for about 1-2 sec in the beginning, much like other amps where the led is labeled "protect" instead.
I opened up the amp and compared the right side element to the left side one.
Apart from the 32A on board fuse that this amplifier has it also has two 10A fuses on each amplifier board. One of these fuses were blown and a lot of transistors were either open or reading very odd on the left side (transistors of the same type as in the V3000 btw) so I replaced almost all of them.
After re-assembeling everything I started her up again and now both channels had only the green "active" led´s ligting up fully, along with the red "fault" for the first 1-2 sec. Everything seemed fine.
However, as I shut the amplifier down the "fault" led´s light up and stay lit for another 3-5min, even when the amp is turned off and the power plug disconnected. Even more odd do I find it that if I try to restart the amplifier withing the next 30min of just having had it on, it blows the fuse of my apartment again(16A) - but if I wait a bit longer, for about 30-40min it starts up again without blowing any fuses.
Could it be that it just has a very hard start up, give that its internal fuse is on 32A and my apartment just on 16A and that it´s actually fine? But in that case why doesn´t it do the same thing all the time and why are the "fault" led´s ligting up for 3-5min everytime it´s shut down.
No schematics on this one and I haven´t tried putting the amp to any speaker so far.
Any idea of what these symptoms might be an indicator of?
Thanks for any and all help!
Best,
J
Last edited:
This is my recommandation:
Put a classical mains incandescent bulb 60W ore more in series with your mains input. This will limit the primary current enabling permanent measurements.
Print the circuit diagramm.
Measure DC-voltages referred to GND and draw them, including measured polarity, into your printed circuit diagramm.
Show a photograph of your results.
My 2 cts
Put a classical mains incandescent bulb 60W ore more in series with your mains input. This will limit the primary current enabling permanent measurements.
Print the circuit diagramm.
Measure DC-voltages referred to GND and draw them, including measured polarity, into your printed circuit diagramm.
Show a photograph of your results.
My 2 cts
moved.- Status
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