1st cap heats up...

[JojoD818]

the 1st cap of my test psu heats up. it's a 4.7uf/450V electrolytic and is used in a setup like this:

280-0-280->5y3gt->4.7uf->1.8K->220uf->2.2K->220uf->load.

the load is constant at 20mA. is it too much ripple?

 

[TonyTecson]

what is the voltage accross that cap?

 

[JojoD818]

i forgot to mention...

around ~330V max during warm-up and ~310V after 60 secs.

 

[djQUAN]

slightly OT: hey jojo, do you know where to get tubes in our area?

 

[ray_moth]

As long as you're sure the cap isn't getting warm from being too close to some other part that gives off heat, then it could be due to ripple. The first cap must be rated for high ripple current.

 

[JojoD818]

slightly OT: hey jojo, do you know where to get tubes in our area?

hi,

there is Spin Electronics in Mandaluyong, I think Deeco also stocks some tubes.

As long as you're sure the cap isn't getting warm from being too close to some other part that gives off heat, then it could be due to ripple. The first cap must be rated for high ripple current.

It is actually near a the 5W 1.8K resistor which feeds the second cap. I will try to put some space between them. I am just worried since out of the three caps, the first cap is the only one that heats up.

 

[TonyTecson]

Pacific Electronics near DEECO is a good source for GE tv tubes and japanese 12au7, 6cg7's cost is 250 per tube.

 

[jarthel]

Pacific Electronics near DEECO is a good source for GE tv tubes and japanese 12au7, 6cg7's cost is 250 per tube.

Where in Manila is deeco and pacific eletronics?

what tubes does spin electronics sell?

any contact number for these places?

thank you.

 

[TonyTecson]

i am in russia at the moment, sorry...

 

[JojoD818]

As long as you're sure the cap isn't getting warm from being too close to some other part that gives off heat, then it could be due to ripple. The first cap must be rated for high ripple current.

I moved the cap away from the resistor and run the test jig for 10 minutes and the cap really is the one heating up by itself and not through passive transfer.

I guess one solution is to remove that cap completely.

 

[Tom Bavis]

a 4.7 uF cap is small amd may have a high ESR, causing heating. A larger cap won't have that problem, but may increase peak current too much for 5Y3. If you remove the cap, you'll have to decrease the value of the first resistor to keep the same voltage (should be at least 2W, since it now has to carry ripple current...). The RCRC filter that's left SHOULD have have enough ripple attenuation...

 

[JojoD818]

exactly what I did. the frist R was reduced from a value of 1.8K to 470R to maintain 320V at the junction of the tube and first resistor.