How Would You Test This Yamaha keyboard PSR-S900 Inverter??

[Paul678]

It's from a Yamaha keyboard, a PSR-S900:




I couldn't find any obvious shorts to ground anywhere. The two
100 Ohm resistors are in parallel in-circuit, and measure a good
50 ohms together.

The secondary coil (pin 7 to 10), measured 368 Ohms.....is this
normal?


There appears to be a healthy +4VDC going into it, but
I don't know how to test the high AC voltage on the
output (isn't it in the 1000s of Volts?), and I don't have
a similar LCD display to test it with.

Would it be safe to use a cracked laptop screen
I have lying around, and hook the inverter cable to it,
and see if the back lights up? Or I remember some of you have
used a neon light bulb to test inverters?

Sorry if this is the wrong place to post this, but I figured
most TVs these days use CCFLs with inverters, so you
guys would be best to ask.

Thanks for any help.....

[budm]

Re: How Would You Test This Inverter??

You can try this, just touch just one of the output terminal with the one end of the CFL. But do not run it too long with the real lamp attached.

[Paul678]

Re: How Would You Test This Inverter??

You can try this, just touch just one of the output terminal with the one end of the CFL. But do not run it too long with the real lamp attached.

Is that lamp meant to run off of 120VAC?

Can I try the same trick with one of those regular
fluorescent spiral 120VAC bulbs? Like the low wattage
13W kind?

[selldoor]

Re: How Would You Test This Inverter??

Yes you can use your laptop bulb just disconnect the panel connector from the laptop inverter and plug into the one you are testing

[Paul678]

Re: How Would You Test This Inverter??

You can try this, just touch just one of the output terminal with the one end of the CFL. But do not run it too long with the real lamp attached.

Ok, I used a regular spiral type 13Watt fluorescent
lamp, touching the center conductor to the
output, and it works rather well. The lamp
certainly shows the high voltage is there, and
the arcing is very pretty when I pull the bulb
away!

Cool trick! Thanks, Bud.

I know the inverter is good.

But the bad news is: I probably have bad CCFLs
behind my LCD display panel, right?

That sounds expensive to replace, because this is a
discontinued keyboard......

But I've heard that people actually replace bad lamps.

Wonder if I can do that in my case? I'll take the display
out and give you some pics......

[tom66]

Re: How Would You Test This Inverter??

If it's a small panel, and you're not worried about originality, replace the backlight with some white LEDs.

[Paul678]

Re: How Would You Test This Inverter??

If it's a small panel, and you're not worried about originality, replace the backlight with some white LEDs.

Ok, I've taken out the panel, and sure enough,
the lamp blew out on one end, and cracked the
tube.

The lamp is quite skinny, a little over 1/16th inch diameter (slightly
over 2mm), and about 4" long (about 10cm). It has little
metal tabs on the ends to solder the wires to.

Any place I can get a suitable replacement?

I couldn't find a original display unit on Ebay.

If I went super bright LED, how would I get the light to form
a straight line, like a tube? And it doesn't sound
easy to modify the circuit so that the brightness knob
controls a much lower voltage, but oh wait, it's likely
to control the brightness by adjusting the 4VDC on the
input of the inverter, so maybe it wouldn't be too bad to do.

Thanks for the suggestion, Tom. Hopefully it's not too
much of a bitch to do!

haha!

[selldoor]

Re: How Would You Test This Inverter??

Perhaps update you profile with country and mains voltage?
If in the US try here: http://www.ccflwarehouse.com/cclawiwi.html
They have them pre wired or plain in 100mm x 2mm or other sizes.
Have you checked on ebay for just the lamp?
I think CCflwarehouse have an ebay shop but I cant remember the name - may be cheaper if you can find it.

[Paul678]

Re: How Would You Test This Inverter??

Perhaps update you profile with country and mains voltage?
If in the US try here: http://www.ccflwarehouse.com/cclawiwi.html
They have them pre wired or plain in 100mm x 2mm or other sizes.
Have you checked on ebay for just the lamp?
I think CCflwarehouse have an ebay shop but I cant remember the name - may be cheaper if you can find it.

HAHA!! Found it!

http://www.ebay.com/itm/2-2-x-100mm-...item3a585ab6bd


Thanks much for the tip, Sell.

I'm gonna buy some digital calipers to make
sure this lamp is 2.2mm diameter.

Damn, you guys are helpful! Much thanks,
and I'll keep you posted.

[budm]

Re: How Would You Test This Inverter??

Glad you found the cause of the problem, I use this lamp trick when I do not have the right connector to attach to the inverter output.

[Paul678]

Re: How Would You Test This Inverter??

Glad you found the cause of the problem, I use this lamp trick when I do not have the right connector to attach to the inverter output.

Well it's a great trick, and very useful indeed. Thanks much.

According to here:

http://www.ccflwarehouse.com/faqs.html

They say your average CCFL life expectancy is about 1.5-3 years
of use in a laptop.

The plastic around the ends of this failed lamp were slightly
melted, due to the heat of the high AC voltage.

Is there anything else I can do to extend the life of the lamp,
besides trying to buy from the best supplier?

I suppose dimming the display screen as much as possible
would be the obvious first step.....

[selldoor]

Re: How Would You Test This Inverter??

Seems like a big worldwide problem
http://www.yamaha-keyboard-guide.com...-comments.html

In there someone uses a cc20100 bulb from ccfl warehouse

[Paul678]

Re: How Would You Test This Inverter??

The keyboard works perfectly now.

Thanks everyone for their input......

[budm]

Re: How Would You Test This Inverter??

Great news and thanks for the feedback, now you can offer repair works for other people.

[Paul678]

Re: How Would You Test This Inverter??

Great news and thanks for the feedback, now you can offer repair works for other people.

I've been repairing electronics for other people for
quite some time, actually even before I found this
wonderful website. But as most of you know,
repairs can be decent money, but even better is
to outright buy the broken stuff for dirt cheap, and then resell
it as fixed.

But I really cannot believe how helpful all of you good
folks have been, and how you've expanded my knowledge
of repair technique, and all for what appears to be
a simple love and/or obsession with electronics in
general, which is certainly what many of us here
seem to share.

I've got to admit, repairing something that has
been left for dead, and bringing it back to life, is
an almost orgasmic sensation!

And so is selling it for a good profit!

[budm]

Re: How Would You Test This Inverter??

Tips and Tricks and the service bulletins/manuals are really good here. A lot of people tells us what the cause of the problems are since none of us will have a chance to work on everything out there, you may run into one broken unit once and can spend a lot of time troubleshooting it, but then you find out some one here already knows what the cause of the problem is, then you can fix it at no time. A lot of great contributors here that are doing it for nothing.

[Paul678]

Re: How Would You Test This Inverter??

Tips and Tricks and the service bulletins/manuals are really good here. A lot of people tells us what the cause of the problems are since none of us will have a chance to work on everything out there, you may run into one broken unit once and can spend a lot of time troubleshooting it, but then you find out some one here already knows what the cause of the problem is, then you can fix it at no time. A lot of great contributors here that are doing it for nothing.

Yes, you would certainly be one of those contributors, much
thanks again to you and everyone else here. You've all helped
me pay the rent and put food on the table.

Some people are too proud to ask questions, but why
spend more time, money, and frustration on a very rare, complex
circuit problem, when someone out there already knows the answer?

It's ironic: The people who want to appear "smart" do
their best to never ask questions, but then consequently, they do
not learn as much as the people who do, and end up
dumber than the rest of us!

[eth]

Re: How Would You Test This Inverter??

Good day

Does any one know what the variable input voltages are for the PSR S900 INVERTER connector CN301 (from E1F)?

I want to go from CCFL to an LED strip / bar, so that I can use the internal brightness control.

Thank you
eth