Which direction does HV diode go??

learpilot2

Member
Joined
Jul 12, 2009
Messages
167
Reaction score
0
Location
HILTON HEAD ISLAND, South Carolina
I have a blooming sea wolf with a bad Varo H386C HV diode. It has a stripe on the end that goes toward the anode cap (tube).

I could only find a NTE 505 rectifier as a replacement. It was slightly smaller in diameter, and has no stripe painted on it, ONLY a "+" marking on one end. Which direction does the "+" marked end go? Towards the tube? I know a stripe goes toward the tube, however, unclear on this "+" marking with no stripe.

Due to the replacement diode being slightly smaller in diameter, it did not fit in the holder. I had to wrap a wire nut winding in each end of the new diode, and cram it in the holder. It sort of stays if you don't move it around. I am afraid it might pop loose. Any ideas???

Thanks

Rick
 
I have a blooming sea wolf with a bad Varo H386C HV diode. It has a stripe on the end that goes toward the anode cap (tube).

I could only find a NTE 505 rectifier as a replacement. It was slightly smaller in diameter, and has no stripe painted on it, ONLY a "+" marking on one end. Which direction does the "+" marked end go? Towards the tube? I know a stripe goes toward the tube, however, unclear on this "+" marking with no stripe.

Due to the replacement diode being slightly smaller in diameter, it did not fit in the holder. I had to wrap a wire nut winding in each end of the new diode, and cram it in the holder. It sort of stays if you don't move it around. I am afraid it might pop loose. Any ideas???

Thanks

Rick

The + goes towards the flyback. The stripe (-) goes towards the tube / anode

Not sure what you mean about the wire nut / cramming

I'm sure that sounds worse than it actually is

All I say is make sure this is the finest connection on the entire cabinet. The HV is not something to get wrong.

Maybe if you post pics it might be easier to see what you mean

:)
 
Let me clarify this so I don't screw it up...

My HV Diode has no stripe. I am familar with the stripe toward the tube.

My NTE 505 stick rectifier is a replacement for the original HV diode. It only has a "+" mark on one end, no stripe.

The data sheet says the "+" side of the diode is the Cathode.

So I put the HV diode in with the "+" side aimed towards the flyback, and the blank side toward the anode cap / tube.

The replacement diode is slightly smaller that the original in diameter. It does not stay in the end sockets so to speak. The end conectors will just fall off. I took a wire coil out of a wire nut, and wrapped one around each end of the new HV diode. It made the ends a little bigger, so they would grab / hold in the end sockets. It does not hold well. Slight tug, and it pulls apart, leave it alone, it stays together. Any better way to solve this issue?

When you said get this connection right, did you mean the polarity, or the quality of the end connections in the end sockets, or both. I did put some dielectric grease in each end socket to help.

Thanks...waiting to fire it up.
 
Ok

I am an electrician

The connection needs to be tight, and not pull apart easily

I am not familiar with your machine's diode

So what I mean when I say "finest" is the connection should be tight, and clean and insulated well
 
The data sheet says the "+" side of the diode is the Cathode.

So I put the HV diode in with the "+" side aimed towards the flyback, and the blank side toward the anode cap / tube.

Yes, the "+" side is the cathode....which is the same as the typical "stripe".
So that end should go towards the tube.

(you have it in backwards)
 
diode.jpg


The Cathode is Negative :D (Not just a personal opinion)

Edit: Add
http://cnx.org/content/m0037/latest/
http://www.allaboutcircuits.com/vol_3/chpt_3/1.html
 
Last edited:
The Cathode is Negative :D (Not just a personal opinion)

Yes.
Electricity also flows from + to - . ;)

Ok, so now I'm just adding to the confusion.

But since the data sheet notes that the + is the "cathode", and the stripe on a typical diode is the cathode, you can denote which way to put it in. You want the electricity to flow towards the tube....cathode end towards the tube.
 
Last edited:
reversed diode..

I reversed the diode, and the picture came back on the screen. It still is blooming, however, it seems like it is being caused by a high B+ voltage, not the HV diode.

Thanks
Rick
 
Back
Top Bottom