[layums]

Hi. I require the part number for D3 on the ray Samuels hornet amp. It's blown. Not sure how it happened. Just sounds distant now.


It's too expensive to send it to ray. Please could some one just PM me the part number. Think it's an easy fix if only I could source the troubled bit.


Here is a close image of what I'm talking about

Thank you all

 

[qusp]

I doubt very much thats your only problem

 

[akiroz]

Quote:

I doubt very much thats your only problem

Yes, something else must have caused it to blow.
It may just blow again after you replaced it.
 
And it is very unlikely that anyone in the community would know unless they work with Ray Samuels or have taken apart their own hornet.
Your best bet is to contact them directly IMO.

 

[layums]

Tried it again today. It sounds normal actually. No other problem suspected. Any ideas for a straight replacement?

 

[akiroz]

Well you can trace what that diode is connected to and try to determine its usage then find another diode that would fit the application.
 
OR kindly ask another hornet owner to take theirs apart to see the part number. (Not likely to succeed but worth trying)

 

[wakibaki]

Looks like those diodes are in series. That would mean they are providing a voltage reference, probably for biassing.
 
You could try measuring the voltage drop across one of the remaining ones. A DMM with diode test will do this for you.
 
The difference you will find is that regular diodes have ~0.6V drop and Shottky have about 0.3V.
 
Chances are that if they are being used as voltage references they will be regular diodes.
 
So you probably just have to find a regular diode that will fit. 
 
The outstanding question is why a diode would fail in those circumstances, considering that all 3 will be passing the same (probably small) current. If that's the case, then the diode had an unusual intrinsic fault.
 
I'd be tempted to take a 1N4148 (leaded) diode and push the leads (briefly) against the pads on the PCB while listening to it. The black band on the diode would go at the same end as the white bars on the existing diodes. See if the sound recovers. At your own risk. Watch for any other signs of trouble such as overheating.
 
The lowest risk solution would be to send it back to Ray Samuels, but you know that already.
 
w

 

[kevin gilmore]

This is the  charging circuit. The 3 diodes are in series and tied directly from the
wall brick to the battery.  Charging currents are very high causing the diodes to crack.
The diode may actually still be ok.  The 9V battery may have a shorted cell.
 
Edit: the diodes are regular silicon diodes.

 

[layums]

Thanks Kevin. Any chance you could suggest a part number. My electrical part knowledge is basic.

 

[kevin gilmore]

need to know the dimensions of the part first, can't tell what size it is.
(this is what happens when you get old)
 
Any surface mount standard diode with a current rating of 1 amp
or more, and the right size will work.

 

[layums]

Will be using Farnell to order. The part is about so big in the picture. 3mmx1.5mm and 0.5mm thick. if you could spoon feed me the part number that would be most appreciated.

 

[kevin gilmore]

this should be the right thing, check the pdf and make sure the size is right.
 
http://fr.farnell.com/nxp/bas16j/diode-commut-75v-0-25a-sod323f/dp/1907599RL
 
http://www.mouser.com/ProductDetail/NXP-Semiconductors/BAS16J135/?qs=sGAEpiMZZMtldOIVIVqa3VG5LWDgyNT6NZm8yZcQ%252bj0%3d

 

[layums]

Any of you guys played with changing the main capacitor?

 

[fakcior]

D3 is not a diode!!! It's weird, but it's 2,4 Ohm resistor.

 

[layums]

Oh I see. Thanks for the input. Do you have a part number. Awesome if you do.

 

[kevin gilmore]

evidently there are at least 2 different ways these were manufactured.
i believe that the resistor is actually 25 ohms.