Hi all,

I currently have an old Ducon capacitor. It's value is 0.01mfd but doesn't tell me the voltage. There is a "vdcw 1000" reading on the side.

The capacitors in my Jaycar guide all have "vdc" ratings, but not "vdcw". Is this the same thing?

If so, then the only thing I can find to replace this small, tube-shaped capacitor is a greencap. Does the shape of the capacitor make a difference to the required usage?
Does it matter if the greeencap is 630vdc rather than 1000vdcw?

Sorry about all the questions folks - have been trying to research this and not getting any clear answers so I thought I'd ask the experts!

Cheers,
Nick.

1000VDC caps were often used on the Plate bypass of sets and in Car radio power units.

It would help if we knew where it was and what it was in?

For most radios 630VDC Greencaps (Red) and the yellow Metallised Polypropylene etc. will sufice.

Jaycar has a limited range of HV caps. I prefer the axials over the greencaps as the leads on the greencaps are often too short.

If you are changing the wax paper caps, in an old set change the lot and every electrolytic as well.

EVATCO is one that will have pretty much all those you want & there are others that appear on the site.

Marc

Hi Mangonick.

The VDCW means 'voltage DC working'. If the capacitor is rated 1000v then you replace it with the same or higher. It doesn't matter whether the cap is polyester or otherwise as long as the type & rating is the same. The axial tubular type are much better for point to point chassis work. Unfortunately Jaycars 2J type polycaps are only 630v. This place here in Melbourne has a range of 2000v polycaps. They are mail order only.

http://speedyspares.com/cat2003-A.pdf

Cheers.

Hi Marc,

Thanks for your reply. I'm restoring a Healing 370 TV set. At the moment it has a problem with the vertical deflection as it only plays a thin white line across the screen. Everything else seems to be ok.

While checking the circuitry in that area of the chassis, I noticed this capacitor was actually only connected on one end. The other end must have snapped off. Perhaps during transportation? Anyeay, rather than reconnecting it, I thought I'd better replace it.

Here's a link to a photo of the capacitor in question.

http://www.flickr.com/photos/90197712@N03/8279897621/in/photostream/.

The capacitor in question is from the 6cm7 valve for vertical deflection.

Can you recommend any better places here in Sydney to buy capacitors if Jaycar aren't really that comprehensive?

Hi Monochrome,

Thanks for clearing up my concern about the type/shape of the replacement capacitor...

Am checking out the website right now!

Nick.

Ok Glad I asked TV & Radio big difference especially in the EHT generators.

You could actually us a ceramic there & some of those go to several KV. Dry electrolytics can cause issues with sweep circuits and a few of those sets used AC bias on the valves, so when the oscillator died, things cooked and then the fuse blew.

Haven't touched a valve TV for decades.

RS components & WES may also be worth a look?

Marc

Dear Mangonick.

Do you have a circuit for this model?
I have a circuit for it if you need one.
One simple thing we did years ago to test the vertical output stage of a television, was to momentarily place a short between the heater supply of the valve (6.3volts A.C.) pin 4, and the control grid of the output section of the valve.
ie short between pin 4 and pin 8 and see if there is any deflection on the screen.
This is a rough and ready test to isolate the fault to either the output, if there is no deflection, or to the oscillator section if there is deflection.

With regards to the voltage ratings of capacitors, early receivers used capacitors of either 200v, 400v, or 600v. This was done for stocking reasons. It is common to find a capacitor with a voltage rating of 200v with maybe 2volts across it.
If you do find a capacitor with an odd voltage like for instance 1600v, do not try to replace it with anything lower. Such a capacitor is C279 0.047/1600v off pin 1 of the 6CM7 valve.
WES components in Ashfield Sydney have a range of 2,000v caps. In this case code MEF.047 $1.15 (2009 price list)
feel free to contact me for any assistance that I might be able to give

Wayne

Test the cap for a short then reconnect it, or use 2 0.02μF greencaps in series. If deflection does not improve then you will need to add more components to your order.