Lexicon PCM 90 Troubleshooting, Rebooting Cycle, Shutting Off?

[canidoit]

The PCM 90 use to keep shutting off and rebooting cycle once in a while. Now, it is just shutting off when I turn it on with the power switch, and sometimes it comes back on and sometimes not.

I read online that this could be an issue with the Power Supply and its a simple matter of replacing the SMPS board.

Does anyone have any tips on how to check if it is the power supply that is at fault?

Thank you.

 

[s2udio]

Classic symptoms of dried up caps.
Before going down a smps rabbit hole just replace all electrolytics in the PSU
Low ESR , decent brand types of course, nichon etc etc.

 

[canidoit]

Thanks for the tip s2udio, but I have decided I might try a short cut on this one as my new year resolution is to spend time on making music. They are selling the power supply and I am considering buying it if I can confirm it is the power supply that is at fault.

Thanks again!

 

[Yash]

I might try a short cut on this one as my new year resolution is to spend time on making music.

Nice resolution. I was making music myself until I fell into this rabbit hole. It's rather hard to dig out from.

 

[canidoit]

I finally got the service manual and checking the power from the rails and the points listed. When it shuts down, the voltage is zero from those points, when the unit works, the voltage is what is described in the service manual.

I removed the power supply module and had a look at the board. It looks like it has been repaired with parts replaced judging by the inconsistent residue of flux underneath and the difference in style of soldering.


Nothing seems to be bulging or burnt, though this component looks dubious with all this brown gunk on it's legs?


Is it safe to say that the power supply is the culprit and so replacing it should fix it?

Any tips to confirm it is the power supply?

Thank you.

 

[canidoit]

OK, just installed a replacement new power supply and it seems to have fixed the issue!

Comparing the new power supply to the old, the old PS board has definitely been repaired.

 

[rock soderstrom]

OK, just installed a replacement new power supply and it seems to have fixed the issue!

Good news!

Comparing the new power supply to the old, the old PS board has definitely been repaired.

Where did you get the spare power supply?

 

[ijzerpro]

Good news!


Where did you get the spare power supply?

I used this one for the PCM91, you can use it also for the PCM90
https://nl.farnell.com/xp-power/sds60ut07/psu-open-frame-60w-3-output/dp/1109924

 

[canidoit]

I bought a new Artesyn LPT45 Power Supply that you can buy online from electronics suppliers. It looks the-same as the original which I think is an Astec LPT45.

I have not tested this properly yet, so hopefully in the next few weeks I should be able to tell if it has fully fixed the issue when I start to use the unit properly.

 

[rock soderstrom]

Thank you for info!

 

[Khron]

Looks very similar to the power supply i replaced in an acquaintance's Axe FX 2, a year or two back.

 

[zamproject]

IIRC I also change my PCM80 with a LPT45
It's more or less a standardized footprint (3x5"), fixing hole, and connectors, that you can find from various manufacturer.