Yamaha Keyboard PSR i455 keys not functioning

[Asit]

I am way away from electronics . I have a problem in hand , and amidst the lockdown , I'm unable to explore servicing options.
The keys E1 , E2 , A#1 and A#2 of my keyboard Yamaha PSR i455 ,have suddenly stopped working . Also the Voice long press is not functioning.
I have cleaned all the contact points and secured the terminals wherever .
Can anyone facilitate .
Kind Regards
Asit

Email address and phone number removed - Moderator

India

 

[rjenkinsgb]

If several keys stopped working at the same time, I'd suspect a wiring fault or bad connection somewhere rather than the keys or key contacts themselves?

Try and follow the connections from the keys, re-seat any plugs and sockets that connect the keyboard to the rest of the electronics and examine all the solder joints very carefully for any that look odd - less smooth & rounded than others.

Do you have a multimeter to test connections?

 

[Nigel Goodwin]

Perhaps been dropped, and a crack in the PCB?.

I repaired one for a friend recently, she'd bought it off Ebay and it arrived badly packed, with the casing broken and parts of the PCB broken off.

 

[dr pepper]

If some keys work then the electronics are probably ok.
Use a magnifier around the traces to the keys that dont work, in fact try to find a common track that goes to all the keys not working, this might be where the break is, sometimes they can be real hard to find if the break is under the green solder resist.
The only way to effectively repair a break is to scrape away the solder resist around the break and solder a piece of wire acorss, you can strip some copper wire out of some old cable, headphones, power leads etc, you can jury rig a solder iron from a large nail and a heat source, but you'll need some solder.

 

[Asit]

If several keys stopped working at the same time, I'd suspect a wiring fault or bad connection somewhere rather than the keys or key contacts themselves?

Try and follow the connections from the keys, re-seat any plugs and sockets that connect the keyboard to the rest of the electronics and examine all the solder joints very carefully for any that look odd - less smooth & rounded than others.

Do you have a multimeter to test connections?

Thanks for your immediate response .I'll follow your advice and see if I succeed ! Yes I do have a multimeter
Best Regards Asit

 

[Asit]

If some keys work then the electronics are probably ok.
Use a magnifier around the traces to the keys that dont work, in fact try to find a common track that goes to all the keys not working, this might be where the break is, sometimes they can be real hard to find if the break is under the green solder resist.
The only way to effectively repair a break is to scrape away the solder resist around the break and solder a piece of wire acorss, you can strip some copper wire out of some old cable, headphones, power leads etc, you can jury rig a solder iron from a large nail and a heat source, but you'll need some solder.

Dr Pepper, 4 keys and the voice long press aren't functioning . I guess these would be "some" keys . I'll also check the way you've suggested .I do have copper strips with conducting adhesive behind which I would use should there be a break along the trace.
Best Regards Asit

 

[Asit]

Perhaps been dropped, and a crack in the PCB?.

I repaired one for a friend recently, she'd bought it off Ebay and it arrived badly packed, with the casing broken and parts of the PCB broken off.

Hi Nigel,
Fortunately there aren't any broken pcbs inside !

 

[Nigel Goodwin]

Hi Nigel,
Fortunately there aren't any broken pcbs inside !

You sometimes get cracks in the track, with no visible signs - do you have a schematic for the keyboard?.

 

[unclejed613]

is that one of the Yamaha keyboards that uses a rubber strip with carbon-bearing rubber dots as the keyswitches? has there been anything spilled on it? that could be a reason for several keys failing at the same time. if some liquid got under the rubber strip it could have left residue on the keyswitch "fingers" (these keyswitches are bare copper interdigitated PCB traces, and the carbon button makes contact when the key is pressed).

 

[Asit]

You sometimes get cracks in the track, with no visible signs - do you have a schematic for the keyboard?.

I dont have a schematic!

 

[Asit]

is that one of the Yamaha keyboards that uses a rubber strip with carbon-bearing rubber dots as the keyswitches? has there been anything spilled on it? that could be a reason for several keys failing at the same time. if some liquid got under the rubber strip it could have left residue on the keyswitch "fingers" (these keyswitches are bare copper interdigitated PCB traces, and the carbon button makes contact when the key is pressed).

Hi, yes it has those , probably silicone rubber moulded switches with black carbonaceous dots . Apparently there wasnt any spill however I cleaned the surface with ipa . Now I’ll clean those black dots which may still have any spill sticking onto them ! Thanks

 

[Nigel Goodwin]

I dont have a schematic!

I couldn't find one either, although I found various other schematics.