Hi all,
This is my first post,
I have 2 power supplies, one good one bad they are 240 volt and have 2 outputs each, one is 5v and the other 12v.
A keyboard I was fixing had an error message on the screen which I worked out as being a power supply issue. I swapped the good supply for bad and hey presto the keyboard was fine but I wanted to fix the power supply.

I slowly began swapping various components until I found the culprit.
It was a capacitor (I think). On the circuit board it says C18 next to it so I assume that means it is a capacitor.

I want to order a new one but I don't know what to order.
As far as I can tell it is very small about 4mm black with 2 silver stripes and 2 8 and I think E or could be E written on it.
I have a diagram and it has 220 over 25 next to it if that helps.

A good link to a page that lists different capacitors/resistors and how to identify them would be great also.
thanks in advance.

 

A quick google search could probably find you other examples of your cap.
As for the value, thats almost certainly 25 volts and 220 (something)farads [farads are a unit of capacitance but most commonly we use microfarads because one farad is acctually HUGE capacitance] so your cap could be 220 micro farads or nano farads or pico farads ... we need a pic to identify it really, but like I said, google can help you better than we can at the moment.

 

220 could also mean 22uF because 221 would be 220uF.

 

Hopefully I have uploaded the image correctly!
I have tried searching on google but I don't know enough about components to choose the correct one. I am relying on finding one that looks the same.



I have uploaded the circuit board diagram, frustratingly I have the parts list for this keyboard but this board is not included on it.

It is a late 1980's board from a korg M1.

 

That looks more like a diode.

 

you will know better than me, I am assuming it is a capacitor because it is labelled C18 on the board. I am by no stretch of the imagination correct.

 

Almost certain that's a diode (Also woo! Synthesizers! I'm getting one of mine repaired at the moment) I have a feeling you may be looking at D6, the labeling for the capacitor may be misleadingly close.

 

Ah yes,
I need your glasses!
So what do you think I need to order?

 

Hello,

In the photo you show a diode.
In the schematic you are pointing at a capacitor of 220 μF / 25 Volts.

Bertus

 

Agreed I am looking for a Diode, that's how much I know, all I know is it does not work and I want a new one.
http://www.ebay.co.uk/itm/50-1N4007-1000V-1A-Silicon-Bridge-Rectifier-Diodes-RoHS-/140595283456?pt=UK_BOI_Electrical_Components_Supplies_ET&hash=item20bc21c600#ht_606wt_902
would that be any good or am I way off the mark?

I am afraid I don't know enough about ratings etc, but I am happy to learn.

 

Hello,

In switching power supplies most times a kind of schottky diodes are used:
http://en.wikipedia.org/wiki/Schottky_diode

Those are faster as standard diodes.

Bertus

 

Ok I am beginning to understand, so what voltage and what amp should I be looking for?

 

Wasn't there a part number above the diode in the circuit diagram? Stick it in alldatasheet.com or google or something, perhaps you could find the exact same kind? Or an equivalent?

 

If it was me fixing it, I would replace with exact diode no. and together with C21,C23,C18 and C19.

The caps are all 220uf/25V. Use low ESR types.

Is the diode no. starting with CRB or ERB

 

I can only see 2 8 and F on it, it might be an e. I will take it off the board to see if I can see any other info

 

Ok it says DF 28 E and the data sheet says crb4402,
I must be getting close.
I can see lots on Ebay for schottky diode but I don't know what amp and voltage to get. I have tried searching the above part numbers with no joy.

 

Then get me a good pic of the diode on the PCB

Scrap that.

Find any 1Amp Schottky diode or better yet, have u got any junk PCB's or Computer power supplies ?

 

that's the best I have got.
I have a few pcbs but I am trying to fix them and re-use. I have pulled parts off one which is in the the picture but the rest I want to repair.
I will gladly buy new diodes 1amp yes any voltage? would a higher amp be better?
Ps the last pic has the wrong part circled.

 

Any black coated diode used in switched mode supplies will be fine for ur replacement.
Just find one of the same size.

 

Thanks,
Maybe one day I will offer advice instead of receiving.
Thanks.