m1muzik - 24 November 2018 04:36 PM

Hello everyone.

Welcome to the forum.

 

m1muzik -

I too am having the same power on issue with my s90 and suspect the similar components are faulty. I wanted to know what places is best to order the voltage regulators and which type is recommended.

The voltage regulators don’t tend to fail.

 

m1muzik -

So far I have ordered parts (electrolytic capacitors and currently looking for SMD chip-type capacitors) from eBay and Amazon. I had tried to order the parts via Yamaha’s support site but I haven’t had any luck especially using the correct part number references from the service manual. Any info would help.

Thanks

The electrolytic caps previously mentioned are typically what needs to be replaced. It’s not necessary to order such parts from Yamaha.

Your member profile doesn’t indicate your location, so making recommendations for parts suppliers is difficult. In the US, Mouser Electronics and DigiKey Electronics are usually good choices.

5pinDIN -

Thanks for the fast reply! Yes, I am located in the United States. I’ll check those two places to order the rest of the capacitors that I need to replace. I have noticed on PSU board that there are darker lines coming from one of the regulators, I figured the regulator in that section would be burnt or needs changing. I’ll continue to replace the capacitors in my case and see it that resolves my power on errors.

Thanks again!

-M1muzik

You’re welcome.

Have you checked voltages to determine if the regulator is/isn’t functioning correctly? Sometimes bad caps can cause excessive dissipation in such a device, or heat sinking is insufficient due to a mounting issue.

Typically Yamaha doesn’t manufacture the power supply, it’s purchased from another supplier. Therefore there’s usually no schematic or parts information for it in the SM. Yamaha provides a part number for the entire PSU.

If you need to replace the regulator, what identification do you see on the part?

Hello,

Sorry for the late reply, I had forgotten my password and tried several times to reset my password and finally I was able to login back. Thank God I had found my password written somewhere in my phone, the password reset on this forum doesn’t work. Here is a picture of the PSU board. The middle section looks alittle dark especially around the voltage regulator area.

Picture 1

Main Picture

Howdy, folks! Joined the forum just so that I could report the successful repair of my S90 based on this thread. So, first, thank you all! For the link to the service manual and also the descriptions of the issue and solution (replacing capacitors).

My S90 also (over the course of a year or more) began displaying the unregistered interrupt error screen over a year ago. And the “solve” of leaving it powered up to “warm up” and then be stable was getting more protracted and inconvenient over time. Came across this thread, found some time and a cheap O-scope (FNIRSI DSO Pro), and then replaced some 47uF surface mount caps, and voila! My S90 boots up straight away now.

So, 1) I wanted to thank y’all and 2) I thought it might be helpful to someone to have some details on my findings in this fix. I looked at IC’s 2, 36, 46, 47, and 57 (all voltage regulators).

(I tried to use BBCode for tables, but that didn’t work out.)
“P-P” is peak-to-peak fluctuation from the DC component, and the “fix” values are measured after soldering in the new caps. Amazingly better! From 10% fluctuations to 2%. Also, I didn’t touch C90 or C154 because their Vouts seemed “clean enough,” and my soldering skills are not great.

I just signed up to report another successful repair of an S90 based on this thread. Thanks a lot to everybody in this thread for sharing all this valuable information!

It’s hard to google the error message, because the codes in it can change. One day I had this error:

Another day this one:

I used the service manual to find the three capacitors C9, C124 and C125 (see page 35 and 36).

I don’t have any device to measure anything on the board, so I just replaced the capacitors with new Panasonic ones (radial, not SMD). I removed the original SMD capacitors first.

That’s what I used as replacement:
- Capacitor model: FC-A 47U 16
- Capacity: 47 µF
- Voltage: 16 VDC
- Ripple Current: 175 mA
- Tolerance: +/-20%

It’s important to put the new capacitors with the right polarity.
- On this page I learned how to read the polarity of the old capacitors.
- The new capacitors have a minus sign on the side

Attached images:
- the tools I used
- the new capacitors

Thanks again!

HELLO!!!!

I too joined this forums to report a successful repair, just like the last poster.  I know that this forums is quite old, just like our S90 keyboards, that are all pushing 20+ years.  I still love using it as a master keyboard with plugins and DAWS on my MAC as well as occasionally using its built in synth sounds.

My problem was exactly as described in the previous posts.  Power on crashes, with the “un-registrated interrupt” message, and “works when warm”, except at the end the problem had become so bad that I could not get it to boot at all even after letting it warm up for several hours.

So I replaced the two caps that are part of the DC-DC conversion circuit for the 5V to 3.3V, which are C9 and C124, both 47uF/16v SMD caps.  Out of caution also replaced the through hole larger caps C160, C161, C164 and C90, which are all 470uF/16V.  Did not replace the regulators, I think they are unlikely to fail.

To anyone else having a problem with your S90.  Replace caps C9 and C124.  These are critical to ensure a steady 3.3V power supply to the main CPU and Tone generator chip, and are highly likely the point of failure.

Thank you to everyone who contributed their insight to this thread, it was EXTREMELY helpful to bringing my S90 back to life!

New here. Not much of a musician but my Wife has an S90.
Same errors.

Also not much of an electronics wiz but I can solder in components.

I am going to attempt replacing the three caps as noted.

Thank you all for posting this valuable information.