Help with X-Amp blowing fuses

[sbisheff]

Hey guys, I picked up 5 X-Amps a few weeks ago and they've been performing flawlessly and sounding great ever since I got them. They run a bit hot so I've spread them out so they're not stacked at all on each other, just in a nice long row with those nice blue LED's staring out :applause: Well last night I came home and I looked and saw one of the LED's was out. I was curious and so I reached behind it to make sure it was on and it was. I unplugged it from all connections, pulled out the fuse, saw it was blown, and replaced it. I plugged it all back in, flipped the power switch and it immediately blew. Thinking it could possibly be wires touching on the speaker side I checked those and they're all fine. I then pulled it completely from the system, not hooked up to anything, replaced the fuse, turned it on and it immediately blew again (only power is hooked up to it, nothing else). I pulled the top of the case, looked around and there's no scarring of burn marks, no popped caps, everything looks perfect. I got out my multimeter and checked for continuity in case there was a short somewhere, starting at the speaker terminals and working backwards through the signal path. I couldn't find any shorts at least from what I could tell.

So at this point I'm stuck, I'm hoping someone with more electronics experience can possibly help? Maybe someone that knows something that happened with these amps that may cause that? I've also got another one that intermittently will stop working but a disconnect of all connections, reconnect and power back up and its fine. I'm a bit stumped and hoping someone can help.

Thanks!

Scott

[HAL]

Hey guys, I picked up 5 X-Amps a few weeks ago and they've been performing flawlessly and sounding great ever since I got them. They run a bit hot so I've spread them out so they're not stacked at all on each other, just in a nice long row with those nice blue LED's staring out :applause: Well last night I came home and I looked and saw one of the LED's was out. I was curious and so I reached behind it to make sure it was on and it was. I unplugged it from all connections, pulled out the fuse, saw it was blown, and replaced it. I plugged it all back in, flipped the power switch and it immediately blew. Thinking it could possibly be wires touching on the speaker side I checked those and they're all fine. I then pulled it completely from the system, not hooked up to anything, replaced the fuse, turned it on and it immediately blew again (only power is hooked up to it, nothing else). I pulled the top of the case, looked around and there's no scarring of burn marks, no popped caps, everything looks perfect. I got out my multimeter and checked for continuity in case there was a short somewhere, starting at the speaker terminals and working backwards through the signal path. I couldn't find any shorts at least from what I could tell.

So at this point I'm stuck, I'm hoping someone with more electronics experience can possibly help? Maybe someone that knows something that happened with these amps that may cause that? I've also got another one that intermittently will stop working but a disconnect of all connections, reconnect and power back up and its fine. I'm a bit stumped and hoping someone can help.

Thanks!

Scott

Scott,
Post a picture of the X-Amp insides and maybe we can help with some diagnostic test measurement points.

[sbisheff]

Will do, I'm heading home now and I'll snap some pics.

Scott

[sbisheff]

Ok here you go:

[HAL]

Scott,
The three large wire connector and two small wire connector appear to be the DC power supply connectors to the amp board. If you remove that connector you can measure the power supply DC voltage outputs.

Disconnect AC from the wall. Remove the DC connector and install a new fuse. Keep your hands out of the unit and then plug it in. If you turn it on, and the fuse survives, then the power supply is possibly ok. This would mean the amp board is probably bad.

If the fuse blows again it is the power supply as you have isolated the amp board from the DC power supply.

If the fuse is ok, you should be able to measure the voltages to see if you have what looks like three different voltages. The black wire should be ground. Be careful as you have live AC and DC voltages in the chassis at this point!

[sbisheff]

Well tried that and the fuse popped but I think something else popped on the power board first! Loud pop and a flash. Unfortunately I'm pretty sure that shield is glued to the board so you really can't look underneath. I think the power board may be dead :( Stinks I only got like 2 weeks out if it.

[HAL]

Well tried that and the fuse popped but I think something else popped on the power board first! Loud pop and a flash. Unfortunately I'm pretty sure that shield is glued to the board so you really can't look underneath. I think the power board may be dead :( Stinks I only got like 2 weeks out if it.

Scott,
If the amp board is ok, there maybe an alternative supply.

IIRC, you can use a +/-24VDC supply at about 6 amps to power the amp board. You would need to consult the amp chip spec sheet for full max current needed. I thing Parts Express has switching supplies that should handle the voltage and load currents. You could remove old power supply board and the AC outlet and feed the DC lines into the hole.

I think the input board needs +/-15VDC on the small connector. I can check mine if you are interested. That could be simple three terminal analog regulators off the +/-24VDC rails.

If that does not sound intimdating, you are half way there! :)

[sbisheff]

Oh that doesn't sound too intimidating at all. If you've got a set you could check that'd be awesome, thanks! The amp board says its 28 +\- vdc if I'm looking at the right spot. I'm listening to my good ones right now and they really sound good, I'd love to find a workaround!

Thanks!!

Scott

[HAL]

Oh that doesn't sound too intimidating at all. If you've got a set you could check that'd be awesome, thanks! The amp board says its 28 +\- vdc if I'm looking at the right spot. I'm listening to my good ones right now and they really sound good, I'd love to find a workaround!

Thanks!!

Scott

If the board says +/-28VDC, that is the place to start.

Take a look at this. You would need 2 for a balanced supply. You might be able to tweak the output from 24V to 28V.

http://www.parts-express.com/pe/showdetl.cfm?partnumber=320-316

[sbisheff]

Does this amp board have a balanced supply input? Is that why its +\- 28vdc not just +28vdc? That supply won't fit, unfortunately, its too wide and too deep. :( At 100 bucks for just power I think it just costs too much to fix, at least with that option. Maybe someone has one with a bad amp board I could get their power board :D Crud this is irritating. Guess I shouldn't have bought these.

[sbisheff]

Ok so I transferred the amp board from the amp that didn't work to the amp that had intermittent output and now I have one fully functioning amp. That's the good news. The bad news, I'm now down one :mad: maybe I should start picking up spares for parts. Haha.

[HAL]

Scott,
You might try PMing Murrel to see if he worked on X-Amps when he was the Tech. He might have some advice.

[sbisheff]

Good idea, I've got his contact info, he helped me with my MFW's as well.

Scott

[bkellison]

I have a pair of x-amps that I am not currently using sitting in my closet. I bought them b-stock about a week before av123 went out of business. If you are interested in buying them let me know, I wouldn't charge much for them.

Of course I understand if you don't want to sink any more money into them as well. Let me know if you are interested, and good luck.

Brian