I need tips on how to solder and repair Yamaha P-95 keyboard

Thread Starter

megc33

Joined Sep 4, 2021
2
Hello AAC members !

I 'd like to thank you for all these advices and feedbacks :

I had the same issue with a P95.

As a newbie with electronics soldering, I bought a starter kit and a couple capacitors, then replaced C216 . I damaged the printed circuit when removing C217 so didn't replace this one :)

I replaced C408 just in case also, and the piano works, except the left speaker maybe that C2
17 left over , but its all right , as I already thought my piano was dead !

Thanks again to the community

Best regards.

Eric

Hi! Do you or any other people on this thread have any advice on how to learn how to solder/ replace the capacitors?? I bought a cheap soldering / desoldering unit from amazon, a multimeter and capacitors but am nervous / don't want to ruin the P-95 I have with my lack of knowledge! Any suggestions on learning how to do this / how you figured it out? Much appreciated!!

Moderator edit: New thread created from here.
 

dl324

Joined Mar 30, 2015
13,490
Welcome to AAC!
I bought a cheap soldering / desoldering unit from amazon
Post a picture of the soldering iron and the dimensions of the tip. What does the desoldering unit look like?

There are a lot of tutorials on the internet for soldering. Basically, you apply enough heat to melt the solder and suck/wick the melted solder from the joint. It takes some practice to get the timing right. Old unimportant PCB's are useful for practicing on.
 

Thread Starter

megc33

Joined Sep 4, 2021
2
Hi, I bought this one from amazon
Vastar Soldering Iron Kit, 60W Adjustable Temperature Soldering-iron Gun Kit with Desoldering Pump, Soldering Station, Tweezers and Wire Stripper Cutter for repairing electronics https://www.amazon.com/dp/B0833XN8P...abc_C371P9VHD8T8Y5NW2RE9?_encoding=UTF8&psc=1

I also bought this multimeter to check which capacitor went out, but now i’m worrying it won’t work well to test which capacitor is bad when they’re still in the circuit board. Should I remove a few candidates and test them w/ the multimeter on their own / not in the circuit? Or use a different measuring device to tell? Or just look by eye (??)


Digital Multimeter for Measuring Voltage, Resistance, Current, Continuity, Battery and Diode Multi Tester with Premium Probes, Backlight, Case, Stand https://www.amazon.com/dp/B086Q4PKYT/ref=cm_sw_r_cp_apip_QbsXMi8YrdSn1
 

Dodgydave

Joined Jun 22, 2012
10,082
That multimeter won't check capacitors , only Ohms, as for soldering set the iron on 350 C and put some solder on the tip when the solder melts put the tip on the capacitor leads on the pcb and at the same time pull or wiggle the capacitor with you fingers or tweezers until it becomes loose and pull it out.
 

dl324

Joined Mar 30, 2015
13,490
I also bought this multimeter to check which capacitor went out, but now i’m worrying it won’t work well to test which capacitor is bad when they’re still in the circuit board. Should I remove a few candidates and test them w/ the multimeter on their own / not in the circuit? Or use a different measuring device to tell? Or just look by eye (??)
Even if the DVM could measure capacitance, in general, you can't measure components in-circuit. You need to remove one lead to get a valid reading.

The best device to use for checking caps for functionality is an oscilloscope. If the cap is for supply filtering, you could have others in parallel. If one isn't working, supply ripple would be larger. You wouldn't notice a problem until it became large enough to cause things to malfunction. Visual inspection can only help to find ones that are bulging or leaking.

To remove caps, heat the solder until it's melted and use the solder sucker to remove the solder. Repeat until you have enough solder removed to break the lead away from the pad. Sometimes you need to add solder to remove it. Be gentle so you don't damage the pads. I use tools like this:
1633816862161.png
GSR-107: Jameco Benchpro : 6 Piece Soldering Aid Tool Kit : Test, Tools & Supplies

When I replaced some bad caps in my DVR, the caps fell away from the board as soon as I removed solder from the last lead (because the holes were over sized and it was a single sided board).

You can use the wiggle method, but you're still going to need to remove the solder from the holes for the replacements. I think you're less likely to pull up the pad (more of a concern on single sided boards) if you remove the solder with the lead still in the hole.
 
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