Got one in very rough condition but has since been serviced to "semi" working order. Any input would be greatly appreciated...
Symptoms:
Loud crackle / pops / noise
- VERY irregular/intermittent... can sometimes use the amp a whole day without any issue
- happens even if there are no sources connected (absolutely nothing plugged in the inputs)
- comes out of both channels
- loudness dependent on volume level (ie: it gets louder/softer depending on how high/low volume is set)
Actions taken:
1. Cleaned volume pot
2. Resoldered some visibly poor solder joints on the preamp board
Questions:
1. Can this type of behavior be attributed to the preamp section or power amp section? I'm hoping to isolate it in order to minimize parts I have to disassemble
2. Are these signs of failing capacitors or perhaps something else?
3. Can this also be caused by irregular current from my wall sockets? The house is pretty old and I'm using a stepdown transformer so I'm considering buying a decent voltage regulator if this is the possible culprit.
Thanks in advance!
Symptoms:
Loud crackle / pops / noise
- VERY irregular/intermittent... can sometimes use the amp a whole day without any issue
- happens even if there are no sources connected (absolutely nothing plugged in the inputs)
- comes out of both channels
- loudness dependent on volume level (ie: it gets louder/softer depending on how high/low volume is set)
Actions taken:
1. Cleaned volume pot
2. Resoldered some visibly poor solder joints on the preamp board
Questions:
1. Can this type of behavior be attributed to the preamp section or power amp section? I'm hoping to isolate it in order to minimize parts I have to disassemble
2. Are these signs of failing capacitors or perhaps something else?
3. Can this also be caused by irregular current from my wall sockets? The house is pretty old and I'm using a stepdown transformer so I'm considering buying a decent voltage regulator if this is the possible culprit.
Thanks in advance!
Of course it could be the preamp section but if you have"bad mains electricity " it could equally be coming via the electric supply .
This type of fault actually appeared many times on the public help website I was on it took a good bit of tracing in many cases and the poster was surprised at what was causing it.
But its easy to find out if its the mains electricity take it to a friend/neighbor and try it there.
This type of fault actually appeared many times on the public help website I was on it took a good bit of tracing in many cases and the poster was surprised at what was causing it.
But its easy to find out if its the mains electricity take it to a friend/neighbor and try it there.
Thank you for the information, if you do not have the service manual it can be down loaded from here.
TEAC A-H500 Integrated Stereo Amplifier Manual | HiFi Engine
As the fault your describing is on both channels then we are looking most likely at a common cause.
In the first instance the speaker protection relay should be replaced RY51 to eliminate it, the relay contacts become oxidised and worn causing intermittent loss of Audio and noise related issues.
Then after testing if the noise is still present check the following.
The Amplifier uses 5 switching ICs for the various inputs IC12 to IC16 on the input selection board.
The left and right channel inputs for a particular input are not common to a single IC but shared between two ICs.
The outputs from the ICs are connected to the common switching contacts of RY11 relay.
This is the point you would need to check for the noise using a Audio signal tracer, before and after the switching contacts.
Audio signal tracers can be purchased or built for a relatively low cost.
Also switch to CD direct mode and advise if the noise is still present.
CD direct will by pass the tone control circuits.
TEAC A-H500 Integrated Stereo Amplifier Manual | HiFi Engine
As the fault your describing is on both channels then we are looking most likely at a common cause.
In the first instance the speaker protection relay should be replaced RY51 to eliminate it, the relay contacts become oxidised and worn causing intermittent loss of Audio and noise related issues.
Then after testing if the noise is still present check the following.
The Amplifier uses 5 switching ICs for the various inputs IC12 to IC16 on the input selection board.
The left and right channel inputs for a particular input are not common to a single IC but shared between two ICs.
The outputs from the ICs are connected to the common switching contacts of RY11 relay.
This is the point you would need to check for the noise using a Audio signal tracer, before and after the switching contacts.
Audio signal tracers can be purchased or built for a relatively low cost.
Also switch to CD direct mode and advise if the noise is still present.
CD direct will by pass the tone control circuits.
Yeah, will try to plug it elsewhere, though I'd really want it to work where its situated now. The only reason why I suspect this is that my CD player was acting up too. Took it apart this morning, replaced the lens assembly, put it back together and it worked when I plugged it in (a socket near my table). I brought it back to where the amp was and it acted all wierd again. Am surprised that, as you mentioned, "bad mains electricity" is actually a thing.
Thanks for this!
For the speaker protection relay, would it still be suspect if there is no audio loss? The noise is present but audio doesn't cut off.
I will research on your recommendation about the audio signal tracer. Thanks. Didn't think the ICs would be suspect.
On the website I used to be on this was a major topic in relation to interference via the mains caused by many seemingly unrelated pieces of household electrical equipment .
Many disbelieved but on insistence persevered and one poster traced it to a guys wife turning on an electrical appliance at odd times of the night .
Nearly 100 posters complained of faults in their Wi-Fi ( slowing it down ) turned out in several of those cases it was some guy running a welding business down the road .
Telephone systems being digital now are also affected if located in engineering factories I was out to many used a $20,000 mains fault tracer left for several days then checked for system cutting off at odd times.
Many disbelieved but on insistence persevered and one poster traced it to a guys wife turning on an electrical appliance at odd times of the night .
Nearly 100 posters complained of faults in their Wi-Fi ( slowing it down ) turned out in several of those cases it was some guy running a welding business down the road .
Telephone systems being digital now are also affected if located in engineering factories I was out to many used a $20,000 mains fault tracer left for several days then checked for system cutting off at odd times.
The speaker protection relay should be replaced, due to the age of the Amplifier.
This is a very common issue with this model
of Amplifier and many others.
The Audio signal tracer will enable you to quickly identify the source of the noise.
@duncan2
good information, thank you! come to think of it, this would be the first time i plugged equipment directly into the mains. i would normally use an auto voltage regulator or at the very least, a surge protector. just realized.
@Audio Service
thanks again. i will definitely replace it.
good information, thank you! come to think of it, this would be the first time i plugged equipment directly into the mains. i would normally use an auto voltage regulator or at the very least, a surge protector. just realized.
@Audio Service
thanks again. i will definitely replace it.