I was given this amplifier from a friend of mine who is moving.
I hooked it up today and there is no sound from the right channel.
I am not a DIY’er by any stretch of the imagination but I am wondering if there is an internal fuse that can easily be checked? Before I bring it to an expert?
Any help you can provide is most appreciated.
I hooked it up today and there is no sound from the right channel.
I am not a DIY’er by any stretch of the imagination but I am wondering if there is an internal fuse that can easily be checked? Before I bring it to an expert?
Any help you can provide is most appreciated.
There are internal 6A supply fuses, it's not clear if they are shared between channels or not.
If there are only 2 internal fuses, they are shared, and that is not the problem.
Also if there's little or no DC voltage at the speaker output with power on, it isn't a fuse.
Be careful, the power supply voltage is dangerously high at +/- 85VDC, so don't touch anything.
Even if it is a fuse, this is likely to be an indication of other, more serious problems.
Acurus A250 - Manual - Stereo Power Amplifier - HiFi Engine
If there are only 2 internal fuses, they are shared, and that is not the problem.
Also if there's little or no DC voltage at the speaker output with power on, it isn't a fuse.
Be careful, the power supply voltage is dangerously high at +/- 85VDC, so don't touch anything.
Even if it is a fuse, this is likely to be an indication of other, more serious problems.
Acurus A250 - Manual - Stereo Power Amplifier - HiFi Engine
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There are internal fuses for each channel located on the main output pcb's.
The pcb's run down the left & right sides of the amp & the fuses are located
on the top edge so easy to get at.
These amps are super reliable (I have three) & the only problem have ever had was
blown fuses from a accidental speaker short once.
The pcb's run down the left & right sides of the amp & the fuses are located
on the top edge so easy to get at.
These amps are super reliable (I have three) & the only problem have ever had was
blown fuses from a accidental speaker short once.
Probably the protection circuit is engaged.
Dust clean first.
Powered off check that connectors are all firmly seated.
Build a DBT (100W incandescent lamp in series with the power input).
Helps further damage while testing.
Open it and fit a new fuse if it is blown.
Start by checking if there is DC on the output.
If the amp uses relays for the protection circuit, You have to check before the relay.
They should click when powered on.
If there is DC on the output, You have blown drivers.
Start inspecting the PCB hunting for leaking electrolytics or burned or discolored resistors.
Dust clean first.
Powered off check that connectors are all firmly seated.
Build a DBT (100W incandescent lamp in series with the power input).
Helps further damage while testing.
Open it and fit a new fuse if it is blown.
Start by checking if there is DC on the output.
If the amp uses relays for the protection circuit, You have to check before the relay.
They should click when powered on.
If there is DC on the output, You have blown drivers.
Start inspecting the PCB hunting for leaking electrolytics or burned or discolored resistors.
Good sign. Let the amplifier sit turned off for a couple of hours to be sure it it completely discharged.
Then look at the fuses and replace the blown one. Use only the exact same type.
There does not seem to be a protection circuit in the amplifier. There are no relays.
This person is not technical and should confine himself only to fuse replacement, at most.
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Thank you everyone for your excellent advice. I will spend some time with us this weekend. Everyone have a great night! I will report back on what I found.
You really should find someone near you that knows how to check things inside a amp
You could easily hurt yourself
Good luck. If you were close to me I’d help
But I’m in Florida
You could easily hurt yourself
Good luck. If you were close to me I’d help
But I’m in Florida
Unplug the amplifier *before* resting the circuit for two hours.
Only then open the case.
Looks like I discovered the issue.
The fuse in the right rear position does not match the other three. It appears to be marked 125V 6.3 A while the others are 250 V. Also marked buss AGC6.
All of the RadioShack’s are gone. Any ideas where I can get more of the 250 V?
P.S. the amp was unplugged all night and I used a plastic knife to gently pry the fuses out. Impressed with how clean and organized it is inside.
The fuse in the right rear position does not match the other three. It appears to be marked 125V 6.3 A while the others are 250 V. Also marked buss AGC6.
All of the RadioShack’s are gone. Any ideas where I can get more of the 250 V?
P.S. the amp was unplugged all night and I used a plastic knife to gently pry the fuses out. Impressed with how clean and organized it is inside.
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Is the fuse blown? Just because it's different doesn't mean anything. If neither of the fuses are blown and you still have no sound check the RCA connection at the back of the amp. Some of the old Acurus amps I work on have loose center pins on the female RCA jack inputs to the amp.
If the fuse is blown I'd recommend installing a 1A fast blow initially to verify it'll power up okay without blowing the 1A fuse. If something is shorted and you install another 6A fast blow you risk causing more damage.
If the fuse is blown I'd recommend installing a 1A fast blow initially to verify it'll power up okay without blowing the 1A fuse. If something is shorted and you install another 6A fast blow you risk causing more damage.
if 125V and 250V is the only difference - that's not your problem.
if it is a lower Amp rating, or it is fast-blow and the others are slow-blow (AGC 6 is fast blow), then that could be the issue on turn-on in-rush current failure and you should change to slow-blow. You don't mention the writing on the other fuses?
I would lean towards an actual internal problem - most likely blown transistors (either drivers or outputs or both) on that channel. Other very unlikely option is problem with the power supply - but that usually is a both channel issue.
if it is a lower Amp rating, or it is fast-blow and the others are slow-blow (AGC 6 is fast blow), then that could be the issue on turn-on in-rush current failure and you should change to slow-blow. You don't mention the writing on the other fuses?
I would lean towards an actual internal problem - most likely blown transistors (either drivers or outputs or both) on that channel. Other very unlikely option is problem with the power supply - but that usually is a both channel issue.
Do NOT install slow blow fuses in the DC rails for this amplifier. There are no storage caps behind the DC rail fuses and as such there is no surge at turn-on. Installing slow blow fuses significantly reduces the protection that the fuses provide. I've powered up A250 amps after upgrading them with only .375A fast blow fuses in the DC rail fuse holders and a properly operating A250 will not blow those fuses at startup or idling.
Thanks again for all of your help. I’m going to first try for new matching fast blow fuses.
It appears as if all of the output connections are tight.
Past the fuses, I will be relying on somebody with a lot more experience for me!
Again, thank you so much for all of your expertise in helping out a newbie.
It appears as if all of the output connections are tight.
Past the fuses, I will be relying on somebody with a lot more experience for me!
Again, thank you so much for all of your expertise in helping out a newbie.
do you have a multimeter (DMM) and know how to use it? This helps if we know you can use a DMM, then we can instruct how to test potential problem parts to see if they are in fact bad.
Any other equipment, like a Scope or variac, etc?
Any other equipment, like a Scope or variac, etc?
When You say there is no sound ... Nothing, Nada on that channel when ear placed near the speaker ??
I mean if there is a slight hiss or hum, with fuses intact then the amp is working but the signal is broken somewhere.
I mean if there is a slight hiss or hum, with fuses intact then the amp is working but the signal is broken somewhere.