Argh

First day in something like a month that I get a chance to go make some noise for myself (no kids, wife working, day off, house all quiet) and one of my powered monitors goes up in smoke. No new one in the near future, since I’m still paying 2010 taxes…hmm…what’s more important? Keeping the gov’t happy or monitors?

down with the oppression!
:disagree:

just say no to triple taxation. ???

you could get a scan converter a heck of lot cheaper than a monitor (around $20) and use one of them ancient old Tv thingys we got in the basments and attics…

not an ideal permanent solution but a temporary mediocre one… :peace:


dontcare

What’s a scan converter?

Oh, I see, I mean the speakers – the powered speakers – one of them went boom.

this one here:

http://www.alesis.com/prolinear820

:laugh:

dontcare

You may laugh, but these should not have failed after 3 years of use.
I will avoid Alesis in the future.
argh. And this was not a very popular model, so there aren’t any used ones floating around. I need to learn some 'lectronics.

Bummer! Is it not repairable?

Quote: (TomS @ Jun. 05 2011, 4:39 AM)


I need to learn some 'lectronics.

A lot of modern stuff is all surface mount technology which is virtually impossible for the hobbyist to repair, but it is worth a look inside Tom.

What actually happened? Did it just stop?

Did it make any noise as it failed?

Did the magic smoke appear? (all electronics runs on magic smoke. If you let it escape the electronics stops working :whistle: )

Does the power light work now?

What's the capital of Peru?

It's also worth emailing Alesis to see it there are any spare boards available or a schematic.

The capital of Peru, Indiana is found at the intersection of Business 24 and Broadway. See for yourself.
http://maps.google.com/maps?f=…73&z=12

As for what happened, the overload light came on and stayed on, and stays on even when there is nothing plugged in. Sound stopped coming out at the same time. So, can you fix it?

Quote: (TomS @ Jun. 05 2011, 9:16 AM)

The capital of Peru, Indiana is found at the intersection of Business 24 and Broadway.
See for yourself.

http://maps.google.com/maps?f=....73&z=12

:D

Quote: (TomS @ Jun. 05 2011, 9:16 AM)


As for what happened, the overload light came on and stayed on, and stays on even when there is nothing plugged in.
Sound stopped coming out at the same time.
So, can you fix it?



Well, my degree is in Electronic Engineering but it's been some time since I did any real electronics proper.

If I were you I'd take it apart (unplug from mains first of course), and make a note of the part numbers of the individual modules/boards inside. Maybe take some pics too. It sounds like the amp module/section rather than something simple like power problem.

Have you got a multimeter? It's worth checking that the speaker hasn't gone short or open circuited. Disconnect it from the rest of the circuit and set your multimeter to Ohms/resistance. Select a suitable range and probe the speaker connections. You should get something around 4, 8 or 16 ohms most likely. If you don't have a multimeter a quick (quick!) touch with a 9v battery should be enough to hear a click and see the cone move.

Found this:

http://docs.google.com/viewer?..BWazUeg

Will have a proper look later - need to go out now.

Hmm, looks like I need to sort out the link too.

how about this link:

http://docs.google.com/viewer?..P7yickN

Awesome. Thank you. Yes, I do own a multimeter. Won’t be able to get to this today, perhaps not until Monday…but this is awesome, thank you!

Nice one, Mark. What d’you reckon to the LED hanging (Tom! without power?)?

No, not without power, but without any audio signal in.

Same as Mark. Years since I had to look at a schematic. Without having this on my bench and hooked up to the old “O” scope and Hz generator it’s hard to tell. Gosh do I hate working on SMT stuff. Not only do I have to wear my glasses, cheaters, I got to get out my hugh magnifier with built in lamp as well.

Not familiar with the NJM5532 or LM38 op amp but from what I can see on the schematic and from your stated symptom, it could be anything from a bad cap allowing DC to pass creating and errant signal, to a bad op-amp or trany, that is in constant saturation. Hence the automute and clip light are on.

Is the “Red Clip” light on even if the unit is completely disconnected from an audio source? Tried running the volume knob all the way up and down several times, see if the light goes out?

And if you have to send it back to Alesis for repair you can most likely send the electronics and not the speakers and cab…saves on shipping.

Duff

Thanks Duff – yes, red clip light is on when no audio cable is plugged in, it is on when the volume is at 0, as well as when it is cranked all the way.
Good idea about the shipping.
I will open it up and take a look to see if it is anything obvious. Still pisses me off. Darn thing is only 4 years old, should not have failed. This is the second product I’ve had from them that has left me unimpressed. Well, ya get what ya pay for.