Hi all,
This is my first post. My humble amp is from videologic, model sirocco 2.1. Though it's just a budget monitor for PC, it's has served me well over the years and i hope to repair it.
Recently, the right channel volume is getting softer & softer until there's no more sound. Initially, after power-cycle the amp, the sound will be back and slowly fade till no sound. I swapped to left channel and the problem follows, so it's confirmed the amp right channel giving problem. I tried opening up the amp and look for any capacitor leakage but to no avail. I tried to moved slightly some of the inductors & capacitors and suddenly there's sound from both channels. However, the problem comes back after about 5 hrs of usage.
Now, the only working channel is beginning to show some signs, e.g sound will start to sound harsh on & off. I tried to email videologic for the amp circuit diagram since its been eol but they rejected the request. So now, i need some experienced gurus here to give me any advice.
link
This is my first post. My humble amp is from videologic, model sirocco 2.1. Though it's just a budget monitor for PC, it's has served me well over the years and i hope to repair it.
Recently, the right channel volume is getting softer & softer until there's no more sound. Initially, after power-cycle the amp, the sound will be back and slowly fade till no sound. I swapped to left channel and the problem follows, so it's confirmed the amp right channel giving problem. I tried opening up the amp and look for any capacitor leakage but to no avail. I tried to moved slightly some of the inductors & capacitors and suddenly there's sound from both channels. However, the problem comes back after about 5 hrs of usage.
Now, the only working channel is beginning to show some signs, e.g sound will start to sound harsh on & off. I tried to email videologic for the amp circuit diagram since its been eol but they rejected the request. So now, i need some experienced gurus here to give me any advice.
link
Usually the solder joints are bad to start with, over time they get even worse. So like they recommended already, grab your iron and rework them. Doesn't take much at all. Do all the joints with external connections/jacks etc, do all the ones for bigger components, like the power supply caps you mentioned after the transformer, do all the ones that seem to have a hairline crack upon close inspection (magnification and a good light help). Even if it works again for the time being it's not a good idea to leave it like that. The output inductors just add a bit of HF filtering, six seems like alot though, would be interesting to know their configuration.
here's some pic of the amp cct
the 6 caps are 25V 4700uF
the 6 caps are 25V 4700uF
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
Hi kerwen,
It looks like a standard chip type amp. Those output inductors are for each channel (one per). Very standard.
As Hugo correctly suggested, go over the solder joints. Use a little solder flux and apply any extra solder spareingly. Do not create solder bridges. The parts mounted to the heatsink are most prone to have cracked connections. You may not even be able to see them.
-Chris
It looks like a standard chip type amp. Those output inductors are for each channel (one per). Very standard.
As Hugo correctly suggested, go over the solder joints. Use a little solder flux and apply any extra solder spareingly. Do not create solder bridges. The parts mounted to the heatsink are most prone to have cracked connections. You may not even be able to see them.
-Chris
hi Chris,
Thanks for the advice, i will resolder those joints and see if that solve the problem. For this amp, they design each channel there's 4 sets of wire, 2 goes to the tweeter & 2 goes to the midrange. Lets say if i want to connect to some other bookshelves, can i connect the 2 high together & vice versa for the 2 low? Will it improve the sonic characteristics if i change the 6 caps to those audio grade caps? Thanks for attending to my questions.
Cheers
Kevin
Thanks for the advice, i will resolder those joints and see if that solve the problem. For this amp, they design each channel there's 4 sets of wire, 2 goes to the tweeter & 2 goes to the midrange. Lets say if i want to connect to some other bookshelves, can i connect the 2 high together & vice versa for the 2 low? Will it improve the sonic characteristics if i change the 6 caps to those audio grade caps? Thanks for attending to my questions.
Cheers
Kevin
Hi Kevin,
This is a budget amplifier in a closed system. Don't run any speakers in parallel. You can try running completely different speakers, but with the same resistance or higher as the originals.
You may be able to improve the sound by bypassing some caps with film types. Particular brands do not seem to offer huge differences as long as they are the same type of part. Don't go nuts. Depending on the op amp types, you may be able to make some improvement there. Maybe.
-Chris
This is a budget amplifier in a closed system. Don't run any speakers in parallel. You can try running completely different speakers, but with the same resistance or higher as the originals.
You may be able to improve the sound by bypassing some caps with film types. Particular brands do not seem to offer huge differences as long as they are the same type of part. Don't go nuts. Depending on the op amp types, you may be able to make some improvement there. Maybe.
-Chris
updates:
I have resolder most of the joints especially those caps, inductors, parts under the heatsink, all the pots, inputs & outputs. Bad news is the problem on the right channel still remains, there was only sound for about 5 mins before disappearing again. Came back on intermittently but most of the time it's off. Any more ideas?
Thanks
I have resolder most of the joints especially those caps, inductors, parts under the heatsink, all the pots, inputs & outputs. Bad news is the problem on the right channel still remains, there was only sound for about 5 mins before disappearing again. Came back on intermittently but most of the time it's off. Any more ideas?
Thanks
Kerwin
One of the tools I make extensive use of is a cap ESR meter.
It comes in handy as electrolytics get old.
Being in Kuwait means loaning it out would be a problem.
Im of the opinion it's one of the best 200 bucks Ive ever spent. Made a lot of money fixing switch mode power supplys in monitors and printers with this puppy.
The one I have here is a "Capacitor Wizard" made by Independence Electronics in the US. Good tool.
It will sniff failed caps for your app.
Much luck
Jack Crow in Kuwait
One of the tools I make extensive use of is a cap ESR meter.
It comes in handy as electrolytics get old.
Being in Kuwait means loaning it out would be a problem.
Im of the opinion it's one of the best 200 bucks Ive ever spent. Made a lot of money fixing switch mode power supplys in monitors and printers with this puppy.
The one I have here is a "Capacitor Wizard" made by Independence Electronics in the US. Good tool.
It will sniff failed caps for your app.
Much luck
Jack Crow in Kuwait
Hi kerwin
Easy way to repair IC powered amplifier,can get one powered pc speaker and use jack plug connected to faulty channel power amplifer input and connect signal to pre input on the power amplifier & signal source,if you can get clear sound from your pc speaker,that your power IC is faulty or no sound that mean your pre-amp(opamp) some one is faulty.
Easy way to repair IC powered amplifier,can get one powered pc speaker and use jack plug connected to faulty channel power amplifer input and connect signal to pre input on the power amplifier & signal source,if you can get clear sound from your pc speaker,that your power IC is faulty or no sound that mean your pre-amp(opamp) some one is faulty.
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