Repairing the power switch on a THR10

Covers entire Yamaha THR range of guitar amps, heads and cabs.

Moderators: Derek, Buzzard, parametric, Saul

IanC
Posts: 4
Joined: Sun Nov 23, 2014 11:51 am

Repairing the power switch on a THR10

Unread post by IanC » Thu Dec 04, 2014 3:19 am

Hi everyone,

I was lucky enough to pick up one of these amps for a bargain price a few weeks ago. The seller pointed out that the power switch was broken, hence the low price. Now I have only tackled minor electrical repairs in the past but was sure that repairing this amp would be fairly straightforward. I joined this forum and received a warm welcome and good advice and am posting some detail about this repair in the hope that it might help other people in turn.
The pictures below show the amp as I bought it, the switch had been almost completely destroyed, although moving it illuminated the amps internal lamps so I knew that the amp was not dead.

Image

Image

The cover was removed by unscrewing the four metal bolts on the front of the amps (Allen key required), the screws on the rear of the amp, and the two screws that are recessed into two of the feet of the amp.
Care should be taken when separating the cover from the body of the amp as the two are connected by two bundles of wires that could be damaged if pulled too hard.

Image

Separation of the amp cover and the body of the amp is possible after unclipping each of the bundles of wires from their sockets on the main circuit board.

Image

Image

You can see from the picture above that the power and selector controls are on one circuit board and the volume, tone etc controls are on the other circuit board.
In the picture above, the solder joints for the power switch are to the left of the circuit board.
The solder joints for the switch were then de-soldered. The four corner solder joints hold a metal frame for the switch in place, whilst the middle three solder joints are the power joints. The following picture shows these joints after the broken switch was removed

Image

As a replacement, I used a simple two position toggle switch that I bought very cheaply from a local electronics store

Image

Soldering the new switch in was a relatively straightforward job. Note that this smaller circuit board can lift away from the cover by unscrewing one screw and also the nut holding the selector knob in place.

Image

Once fitted, reassembly was straightforward,


Image

To my relief, the amp works perfectly and sounds fantastic.

Hope this helps someone, please ask if I have missed something,

Cheers,

Ian

User avatar
parametric
Global Moderator
Global Moderator
Posts: 2188
Joined: Mon Jan 18, 2010 1:00 am
Contact:
Great Britain

Re: Repairing the power switch on a THR10

Unread post by parametric » Thu Dec 04, 2014 4:22 am

Excellent Result Ian, and THANKS for reporting back.

Nice Pics too.

This really is a great example of one of the PRIME reasons this Forum exists.

It demonstrates what CAN be achieved with a little guidance and encouragement.

There is quite a large membership here, and chances are GOOD that someone has "been there before" and can advise . . .

. . . Time to crank it up and ENJOY!

Best Regards

parametric
Alesis Fusion 8SSD AND 6SSD - BOTH are 384Mb/120Gb SSD/Akai ADVANCE61/Yamaha MOXF6/1024Mb Flash Ram/Yamaha SY85/8.5mb vol/1024k non-vol/DX21/Roland MT32/Bachmann double overstrung Baby Grand Piano/Win10 Pro/Ubuntu MATE 15.0.4/iBook G4/Mac OS 10.4.6/ProTools 7.4/MBox2/M-Audio 24/96 Sector101 2x SYEMB06 / 4 x EXM-E3 128MB DRAM Module
BRAND NEW DSDD (720k) FLOPPY DISKS FOR SALE - viewtopic.php?f=22&t=9217

Watch out now! take care, BEWARE of the greedy leaders! They'll take you where you should not go - (George Harrison)

IT'S TRUE - "MONEY TALKS" - TO ME, IT MOSTLY SAYS "GOODBYE" ;-)
http://www.chrisnmiller.co.uk/Chris

User avatar
Buzzard
Specialist Moderator
Specialist Moderator
Posts: 1539
Joined: Wed Sep 04, 2013 7:38 pm
Contact:
Denmark

Re: Repairing the power switch on a THR10

Unread post by Buzzard » Thu Dec 04, 2014 5:43 am

IanC wrote: Hope this helps someone, please ask if I have missed something,

Cheers,

Ian
BRILLIANT Ian ((i)) ((i)) ((i)) ((i)) ((i)) ((i)) ((i)) ((i)) ((i)) ((i)) ((i)) ((i))

Not only did you get the job done, but you've just delivered some of the best pictures of the inside of a THR amp available online.

Thanks for your contribution. :D

Regards
Peter
Yamaholic, Guitars, Amps and Bikes. :idea: My Guitars: viewtopic.php?f=24&t=7004 :idea:

drokia2
Posts: 2
Joined: Wed Oct 26, 2016 6:01 am

Re: Repairing the power switch on a THR10

Unread post by drokia2 » Wed Oct 26, 2016 4:52 pm

@IanC

What power/volatage rating was your two toggle amp. I have a THR10c with a broken power switch (accidentally hit it with another amp). I'm new to this so I dont know how much the voltage and amps matter. The battery says that the output rating is DC 15V 3A.

I'm thinking of getting this one (https://www.amazon.com/Morris-70111-Tog ... itch+spade) but it as 277 Volts and 20Amps. I'm not sure if I want the switch to have more power or less power than the battery. I don't have any soldering tools so I figured I want the spade connectors.

Thanks for your help

User avatar
Buzzard
Specialist Moderator
Specialist Moderator
Posts: 1539
Joined: Wed Sep 04, 2013 7:38 pm
Contact:
Denmark

Re: Repairing the power switch on a THR10

Unread post by Buzzard » Wed Oct 26, 2016 9:31 pm

drokia2 wrote:@IanC

What power/volatage rating was your two toggle amp. I have a THR10c with a broken power switch (accidentally hit it with another amp). I'm new to this so I dont know how much the voltage and amps matter. The battery says that the output rating is DC 15V 3A.

I'm thinking of getting this one (https://www.amazon.com/Morris-70111-Tog ... itch+spade) but it as 277 Volts and 20Amps. I'm not sure if I want the switch to have more power or less power than the battery. I don't have any soldering tools so I figured I want the spade connectors.

Thanks for your help
Welcome to the Yamaha Forums. :D

As long as the switch has the EXACT same physical dimension, size and function, it'll work fine.

The power rating is NOT important as long as the specs of the switch exceeds the power rating of the unit.
(if it didn't, the switch would fry)

The switch you've found online, may take up too much space including the "spade plugs".

Any local electronics supplier/dealer should have the switch needed, it's a common part.

Best Regards
Peter
Yamaholic, Guitars, Amps and Bikes. :idea: My Guitars: viewtopic.php?f=24&t=7004 :idea:

drokia2
Posts: 2
Joined: Wed Oct 26, 2016 6:01 am

Re: Repairing the power switch on a THR10

Unread post by drokia2 » Sat Oct 29, 2016 11:52 pm

Thanks Buzzard,

This is super helpful. I'm excited to have my amp back :).

User avatar
Buzzard
Specialist Moderator
Specialist Moderator
Posts: 1539
Joined: Wed Sep 04, 2013 7:38 pm
Contact:
Denmark

Re: Repairing the power switch on a THR10

Unread post by Buzzard » Sun Oct 30, 2016 5:29 pm

drokia2 wrote:Thanks Buzzard,

This is super helpful. I'm excited to have my amp back :).
Looking forward to see how you get on,

The soldering is really not difficult, but if you're not familiar with soldering,
anyone you know with basic skills, should be able to help you out.

Regards
Peter
Yamaholic, Guitars, Amps and Bikes. :idea: My Guitars: viewtopic.php?f=24&t=7004 :idea:

User avatar
Buzzard
Specialist Moderator
Specialist Moderator
Posts: 1539
Joined: Wed Sep 04, 2013 7:38 pm
Contact:
Denmark

Re: Repairing the power switch on a THR10

Unread post by Buzzard » Thu Mar 09, 2017 5:15 pm

:idea:
Yamaholic, Guitars, Amps and Bikes. :idea: My Guitars: viewtopic.php?f=24&t=7004 :idea:

Post Reply

Return to “Yamaha THR Forum”

Who is online

Users browsing this forum: No registered users and 1 guest