I was given an MTX Sub8 powered sub with 100w amp. The reason my friend gave it to me was because it started blowing fuses and would never stay powered on for more than 3 seconds.
I pulled the amp out and looked over everything but nothing is obviously blown or burned up. Where do I start?
I checked the continuity of the transformer and it checks good so there aren't any broken windings as far as I can tell. The 2 larger caps (35v each IIRC) seem to be charging up evenly with the multimeter test, I checked the NPN transistor and it showed 0 on the hFE. I then checked it later and it showed 1, so I'm not sure what that means. What else can I check? Could it be as simple as the on/off switch shorting out? Yes I am using the 1 amp slow burn fuses it is supposed to use.
I'd like to fix this amp instead of buy one, I don't know of any reason this thing is not repairable.
Thanks
I pulled the amp out and looked over everything but nothing is obviously blown or burned up. Where do I start?
I checked the continuity of the transformer and it checks good so there aren't any broken windings as far as I can tell. The 2 larger caps (35v each IIRC) seem to be charging up evenly with the multimeter test, I checked the NPN transistor and it showed 0 on the hFE. I then checked it later and it showed 1, so I'm not sure what that means. What else can I check? Could it be as simple as the on/off switch shorting out? Yes I am using the 1 amp slow burn fuses it is supposed to use.
I'd like to fix this amp instead of buy one, I don't know of any reason this thing is not repairable.
Thanks
If it's a bad power supply, it can either be repaired or replaced. diyAudio is the perfect place for these "I CANNOT find anything like it" situations.
As for the question, I was going to include in my first post... Remember 3 words when troubleshooting - safety, divide, and conquer. In that order.
Having said that, heat is the enemy of electronics so it can often be assumed that a failure is in that part of the circuit that handles a lot of heat/power, eg the discrete output transistors or chipamp.
As for the question, I was going to include in my first post... Remember 3 words when troubleshooting - safety, divide, and conquer. In that order.
Having said that, heat is the enemy of electronics so it can often be assumed that a failure is in that part of the circuit that handles a lot of heat/power, eg the discrete output transistors or chipamp.
Well, to say the least, I am a little new at this. So my amp is a chipamp according to where the mods put this post. The transistor I was referring to is a TIP122 100v that is attached to the heatsink next to the TDA7370B chipamp.
eBay has been my saving grace as I can pretty much replace everything on the circuit boards for about $35. I don't want to do that, but I have a couple of capacitors that have a stained brown tinge to them like they leaked or something leaked on to them. I am going to replace these as they are cheap. I am also going to replace the chipamp and the TIP122 transistor I'm pretty sure.
How can I check the chipamp to see if it is good or not? This is the most expensive piece to replace so I want to make sure it is or isn't the problem.
eBay has been my saving grace as I can pretty much replace everything on the circuit boards for about $35. I don't want to do that, but I have a couple of capacitors that have a stained brown tinge to them like they leaked or something leaked on to them. I am going to replace these as they are cheap. I am also going to replace the chipamp and the TIP122 transistor I'm pretty sure.
How can I check the chipamp to see if it is good or not? This is the most expensive piece to replace so I want to make sure it is or isn't the problem.
Is there only one TIP122 transistor? I would say it's probably used as a regulator or something like it, rather than any part of the power amp.
Checking the chipamp would basically mean taking it out of circuit, and building the reference circuit in the datasheet to check it.
Like i said, check the subwoofers voice coil. It might well be fried if the chip is dead.
Checking the chipamp would basically mean taking it out of circuit, and building the reference circuit in the datasheet to check it.
Like i said, check the subwoofers voice coil. It might well be fried if the chip is dead.
You could check the chipamp out of circuit with a multimeter, but that involves some familiarity with the chip and determining what measurements are correct by looking at the datasheet (which hopefully has an internal diagram!). You could possibly power up the circuit with the chipamp removed; if the chipamp is shorted the short will have been removed and the fuse shouldn't blow. Peripheral components like those leaky caps may have taken a hit too and should be replaced.
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