# Yamaha P-105 Keyboard Circuit Board SMD decoding

#### oggy bleacher

Joined Feb 18, 2020
3
I'm researching repair options for this 2013 yamaha piano keyboard and this forum appears frequently with good advice and knowledgeable community.
The keyboard had intermittent functionality. Power light would come on but the instrument sound selection wouldn't default on. An instrument voice selection always came on automatically and now it doesn't. I reset all settings to default and sometimes I could turn it on and off and sound would reappear in both the headphone and on board speakers, but then the sound would disappear, but the issue isn't a headphone/speaker issue since the instrument light doesn't even come on, although the power light does come on, so I know there won't be sound because it's basically stuck in that instant between turning on and selecting the default instrument voice. No buttons work, not even the power button to turn it off. I have to unplug it to turn it off but the power button works to turn back on...though the instrument voice still is not selected. The instrument definitely was moved around a lot in a padded case and spent some time on beachfront property so it's had a full life but if I can repair it then I'd like to try.

I dug around the boards and ribbon cables hoping something would be obviously broken or loose but found nothing. I disconnected the headphone board with no change and there's no obvious bulging capacitors or corrosion but that's what I'm concentrating on.

I've decided to give one last try in identifying the SMD caps to replace since it's a common problem and the symptoms point to a main board capacitor failure. The keyboard is not really worth a manufacturer service repair so it all comes down to identifying these SMD caps, ordering them, replacing them, reassembling it and deciding what to do from there.
Sorry for the glare off the board. (I did a cursory ohm test with a multimeter and the caps that did not register any change in resistance are marked with a black marker dot. But I plan to replace all of them since I don't trust any of them.)

There are 14 SMD caps in total (a few are out of that picture frame) grouped into 6 values...(quantity):
F3 100 25 (2)
3H 100 16V (6)
3F 1 50V (2)
3l 10 16V (2)
100 JFC E43 (1)
F2 220V UD (1)

I have identified the top 4 value groups in kits such as this one on amazon https://www.amazon.com/Eiechip400pcs-1uF-1000uF-Assorted-Electrolytic-Capacitor/dp/B07DC38Z8L/ref=sr_1_1?keywords=smd&qid=1582073619&s=industrial&sr=1-1
or, if I go the radial capacitor route,
https://www.amazon.com/OCR-24Value-Electrolytic-Capacitor-Assortment/dp/B01MSQOX0Q/ref=cm_wl_huc_item

But the bottom two in my list are coded in a way I don't know how to unscramble and the tutorials I found were in Hindi so I didn't learn much. I don't know if one in the assortment kit is compatible.

100 JFC E43 corresponds to what values?

F2 220V UD corresponds to what values?

Another questions is about a recommended seller of these capacitors. I couldn't find a friendly looking electronics supplier (Mouser, McMaster Carr, JCarr, Arrow all looked cluttered or catering to bulk purchases.) to purchase them a la carte, so that's why I'm looking at more expensive assortment kits. I'd rather simply buy two of each and not invest more money in parts for what could be a junk unit.

#### oggy bleacher

Joined Feb 18, 2020
3
update, the parts arrived and there are two that look like there's 1 mm or 2mm difference in form factor/base. I don't know if that will affect the soldering process yet.

100 25V (2) looks slightly smaller than the original
220 35V (1) looks bigger all around than the original.
That looks like it won't fit.

The others look exactly the same form factor but the printing font is different.
Next step is replacement.