Alesis Fusion 8HD PSU problem

[Christoph]

Hello,

I am new to this forum and have signed up, because I have a problem with the PSU of my Alesis Fusion 8HD. The Alesis Fusion began to reset and restart during playing. Sometimes several times in succession. Lately I had to turn the Fusion off and on again (sometimes several times) in order to play, because just the backlight and some leds were on. And there was smell like burning plastic.

I suspected a PSU problem and have removed it. Some images of the PSU are appended here (before and after cleaning). As you can see, there is obviously a problem and I have some questions:

1) What is the brown/black stuff on the diode?
2) Is this diode built into each PSU or was it retrofitted?
3) What components should I replace?
4) I have a voltmeter. Can I measure anything?
5) Why some of the components getting very hot? The PSU circuit board is dark in some areas (see the red arrows in one picture).

Thank you in advance for your help... and excuse me for my bad english.

Best regards
Christoph

[Jesse]

Looks to me like you need to replace the PSU

https://www.alesismusic.com/viewtopic.php?f=2&t=5933

[Christoph]

Hello Jesse,

I know I can by a new PSU, but I want to try to repair the old one. Does anyone has the schematics or can tell me which parts (resistors, capacitors etc.) should be changed?

Christoph

[Jesse]

Hello Jesse,

I know I can by a new PSU, but I want to try to repair the old one. Does anyone has the schematics or can tell me which parts (resistors, capacitors etc.) should be changed?

Christoph

Good Luck, unfortunately No one that we know has the schematics, it would be nice to have them though

[Jesse]

Each case is different, but here is what one Fusion owner did to repair his PSU

http://www.promusicproducts.com/forum/p ... f=2&t=5943

[cindy_fusion]

I tried to "component" fix my supply..no luck...even ha a DC-DC expert look at it that designs supplies for electric vehicles. As Jesse stated, this was an OEM supply that Alesis purchased and did not design themselves, hence there are no schematics to be found.

It is pretty difficult if not impossible to fix a switch mode (quad output) power supply without a schematic and ref diagram (with test point voltages).

Jesse can provide you (or you can look in the "dead fusion" thread) to see what the appropraie output voltages are.

Your supply definitely overheated...if your unit still works with that type of burn marks, it is a miracle..and could cause furethr problems very soon..(perhaps a high voltage on a critical component like the DSP, hard drive, or memory.

I agree with jesse, buy a new powersupply before they are all gone....gone for good (117 dollars).

Cindy

[Christoph]

I managed to repair my PSU wih the help of a electronics forum. This are the things I have done:

- resolder cold/broken solder joint on the AC-side
- replaced some SMD resistors
- added a second heat sink to the small one on the AC-side

Things to be done:
- add a second fan on the AC-side of the PSU
- make a new side plate from wood with holes to ensure air-flow

You can read the whole story on http://www.mikrocontroller.net/topic/291215#new. It is written in german, so Google translator (http://translate.google.com/) may be helpful.

All in all the PSU is not very good designed (some resistors are to small; heat sink is to small etc.) . But the worse thing is that it is build into the synth without adequate air-flow in a closed box. Shame for Alesis...

Christoph

[sonicwarrior]

Reading the German thread I'm thinking of modifying the PSU in my 8HD before anything happens. The wooden endcaps with holes also sounds like a good idea. It might be even better to use metal there but the shapes would make this pretty expensive.

Btw.: Was it hard to open the case?

[Jesse]

I managed to repair my PSU wih the help of a electronics forum. This are the things I have done:

- resolder cold/broken solder joint on the AC-side
- replaced some SMD resistors
- added a second heat sink to the small one on the AC-side

Things to be done:
- add a second fan on the AC-side of the PSU
- make a new side plate from wood with holes to ensure air-flow

You can read the whole story on http://www.mikrocontroller.net/topic/291215#new. It is written in german, so Google translator (http://translate.google.com/) may be helpful.

All in all the PSU is not very good designed (some resistors are to small; heat sink is to small etc.) . But the worse thing is that it is build into the synth without adequate air-flow in a closed box. Shame for Alesis...

Christoph

Cogratulations Christoph, a pdf file with pictures showing the damaged parts replaced and the parts used to replace them might be helpful to other Fusion users in the future

[Christoph]

@Jesse
When all the work is done (maybe at the end of this week) I will write a little tutorial (with pictures).

Christoph