SOLVED Yamaha PSR E403 works on batteries, not on mains

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andy mids
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SOLVED Yamaha PSR E403 works on batteries, not on mains

Unread post by andy mids » Mon Feb 29, 2016 10:44 pm

Hi

My Yamaha PSR E403 works on batteries, but not my tested power adapter.
I get 12V at the inside locations by the mains power supply socket to D152, but not beyond D152.
I am far from having much electronics knowledge, but tested across D152 and D153 both give readings of 700 on a diode test.

Correction - D151 D152 and d153 all test around 700 from positive to negative and open in the other direction, using the diode test setting and the power disconnected. So presumably they are all likely to be working OK.

Just wondering if I have located faulty diodes, and will I be able to change them if faulty.

Advice very welcome on tests and replacing/type etc.

I did notice the following discussion on a similar model which suggest I might have a diode prob.
My board image is posted below.

viewtopic.php?f=48&t=7292&start=15
Re: Can't power up, please help
Les Turnbull » Tue Mar 31, 2015 3:19 pm
Also if reverse voltage had been applied at the power input socket then a protection diode may have blown , In the picture above is D101 a common reverse polarity protection diode , With your multymeter set to OHMS these should only read throughput in one direction , When one blows they can send the voltage straight back to the Power adaptor without it ever feeding the board .

Thanks
Andrew

Image
Last edited by andy mids on Tue Mar 01, 2016 3:19 pm, edited 3 times in total.
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Re: Yamaha PSR E403 works on batteries, not on mains

Unread post by SeaGtGruff » Mon Feb 29, 2016 11:07 pm

I'm afraid I don't have the electrical knowledge or experience needed to offer any advice, but one thing I can recommend is that you get a copy of the Service Manual if you don't already have one. You can download it from the ElektroTanya web site: http://elektrotanya.com/?q=showresult&w ... =&kat2=all

If you have never used the ElektroTanya web site before, note that after you click on the link for the manual you must wait patiently-- for perhaps a minute or so-- until a small "Get manual" link appears in the lines of text in the bottom portion of the page, below the image of the manual's cover page. That is the link that you want to click on to download the manual. If there are any buttons on the screen that say "Download now," those are actually from ads that have nothing to do with the manual, so don't click on them.
Michael Rideout
Current keyboards: Yamaha YPT-400, PSR-E433, PSR-E443, PSR-EW400, MX49 BK
Current controllers: M-Audio Axiom 61-II
Previous keyboards: Farfisa Matador 611; Casio CTK-710
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Re: Yamaha PSR E403 works on batteries, not on mains

Unread post by parametric » Mon Feb 29, 2016 11:24 pm

Hi Andy, - and welcome to the Forums . . . .

My electronics knowledge is likewise not extensive - but as you have found, the diodes allowing voltage both ways is NOT correct.

I would guess that replacing those diodes would solve the issue. Then, double-check that your Wall Wart is supplying the correct voltage AND Polarity.

BTW - it should ideally have a power rating the same as the Yamaha original. This info is sometimes in the User Guide, but should be on the Original Wall Wart itself.

Helpfully, the manual will often only say Yamaha Power supply model nnn . . . . :roll:

How the diodes came to blow is a different question. IME, boards are variously MORE or LESS forgiving of reverse polarity (which is easily done if you are using a replacement Wall Wart, especially a "Universal" one.

Some boards will object (as yours appears to have done - by blowing the diodes), whilst others will simply not work until the correct Voltage/Polarity is presented.

Hopefully, one of our more experienced members will chime in and confirm my "opinion" here . . .

Best Regards

parametric
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andy mids
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Re: Yamaha PSR E403 works on batteries, not on mains

Unread post by andy mids » Tue Mar 01, 2016 6:05 am

Thanks Michael and parametric. downloaded the manual (which I had previously tried to find online for free).
I would like to use this keyboard but it came non-working and without the original power supply, so I bought one advertised as the correct spec.
I will recheck my testing method for the diodes and recheck the power supply spec & polarity.
I would also get some personal satisfaction if can solve this, and find it interesting.
Thanks, and any further comments welcome please.
Looks like the manual is comprehensive and detailed.
Will report back
Andrew
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Re: Yamaha PSR E403 works on batteries, not on mains

Unread post by SeaGtGruff » Tue Mar 01, 2016 8:28 am

You're welcome. I have a YPT-400, which is the same as a PSR-E403 but with a different name, so I think I can say with some confidence that you'll enjoy playing it once you get it working. :)
Michael Rideout
Current keyboards: Yamaha YPT-400, PSR-E433, PSR-E443, PSR-EW400, MX49 BK
Current controllers: M-Audio Axiom 61-II
Previous keyboards: Farfisa Matador 611; Casio CTK-710
andy mids
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Re: Yamaha PSR E403 works on batteries, not on mains

Unread post by andy mids » Tue Mar 01, 2016 11:53 am

I've done a little more work and I have corrected my first post and image.
Diodes D151 D152 and D153 all test around 700 from positive to negative and open in the other direction, using the diode test setting on my multimeter, and with the power disconnected. So presumably they are all likely to be working OK.

I am confuse with the power supply polarity. The power supply central pin reads positive and the outer sheath reads negative.
When connected to the keyboard, the diode D152 side of the circuit appears to be the negative,

I wonder if I have a power supply polarity problem as mentioned by parametric?


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andy mids
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Re: Yamaha PSR E403 works on batteries, not on mains

Unread post by andy mids » Tue Mar 01, 2016 12:06 pm

The only additional info I can find is the manual power supply diagram which suggests central pin should be positive, which appears to be the case.
Not sure what to test next, delighted for any further help.
Thanks, Andrew

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Re: Yamaha PSR E403 works on batteries, not on mains

Unread post by andy mids » Tue Mar 01, 2016 1:07 pm

Testing the voltage around the power input it looked odd, so I've taken the board off and can see a solder crack near one socket connector on the underside of the board, which confirms a lack of continuity I picked up at various places during testing just now. Will solder and see.

SOLVED
Working now, thanks for responses, will post image of fault.
A
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Re: SOLVED Yamaha PSR E403 works on batteries, not on mains

Unread post by SeaGtGruff » Tue Mar 01, 2016 3:41 pm

That's great news! Not bad for a morning's work, eh? :)
Michael Rideout
Current keyboards: Yamaha YPT-400, PSR-E433, PSR-E443, PSR-EW400, MX49 BK
Current controllers: M-Audio Axiom 61-II
Previous keyboards: Farfisa Matador 611; Casio CTK-710
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Re: SOLVED Yamaha PSR E403 works on batteries, not on mains

Unread post by parametric » Wed Mar 02, 2016 2:04 am

great result Andy. The sheer satisfaction of having fixed it yourself is a great buzz too.

It will come as no surprise that MANY mysterious faults turn out to this. It's surprisingly common . . . .

ATB

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 MicroTrack 24/96

NI Komplete11 Ultimate

Sector101 2x SYEMB06 / 4 x EXM-E3 128MB DRAM Module

BRAND NEW DSDD (720k) FLOPPY DISKS FOR SALE - http://www.yamahaforums.co.uk/forum/vie ... =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
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