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[bkenobi]

I have an old Toshiba TV that stopped working since the last time I turned it on (probably a year ago).  I won't go into detail, but I'd prefer to fix it on the cheap rather than junk it.  If I plug it in, I hear the characteristic buzz of an old tube TV powering up but I can't get it to turn on.  I found the service manual and a post that suggests one of the PSU caps is likely the issue.  I checked, and that cap is bad and the fluid had leaked to the bottom of the board making a couple contacts matte.  I cleaned things with white vinegar and removed the bad cap, but I don't have a direct replacement locally.  I can source one for cheap, but it will take a few days to get here.  I was curious if using a 22uF/35V cap to replace the bad 22uF/50V would be extremely bad just to verify that it fixes the issue?  If it does, I'd order the new one and hold off on use until after it's replaced.  If that didn't fix it, I'd possibly just junk the set.

[Brian H]

If the schematic shows the voltage usually found on the capacitor is 35 volts or less. I would be tempted to try it as a test.
If it is over 35 volts. I would be very careful. Though most capacitors do have a higher surge voltage they can stand for a short time.

If the TV power supply is a switcher. I would suggest you get a capacitor rated for switching power supply use. A general purpose one may only work a short time before failing.

[bkenobi]

I don't know what the purpose of this cap is but it is the smallest one on the board I can identify as an electrolytic type.  There are some monsters on there but this one is really small.  I figured that the original being rated at 50V might have been due to easier sourcing, but I have no idea.  I was just hoping I could try the 35V to see if it improves things and then swap the correct one in.  If it blew up, I don't think that's too big a problem as it would just throw paper inside the set, right?  Are there any down sides to using the wrong size as a test (other than destroying the cap)?

[bkenobi]

I found a replacement cap on Google.  They Newark only wants $0.07 + $1.24 tax + $12.24 shipping for qty 1.  Sounds fair.   

I think I'll source it elsewhere.

[dhouston]

Try AliExpress or eBay. You can probably buy a dozen for $0.07 with no tax and free shipping. But, the free shipping takes so long that I usually can't recall why I ordered a particular item.
 
http://www.aliexpress.com/item/22uF-50V-green-High-Frequency-5-11-DIP-aluminum-Electrolytic-capacitor-50pcs/32522901239.html?spm=2114.01010208.3.1.UnF1sj&ws_ab_test=searchweb201556_10,searchweb201602_2_10037_10034_507_10032_508_10020_10017_10005_10006_10021_10022_10018_10019,searchweb201603_2&btsid=941ba367-5fe9-4592-83dc-e5f9180862c7

[bkenobi]

I saw a few on ebay from Hong Kong that were ~$1 shipped for 10+.  They either arrive in a few days or a couple months.  It's sometimes fun to order a few things from China and have that Xmas morning feeling when a package shows up in the mail!

[dave w]

I was just hoping I could try the 35V to see if it improves things and then swap the correct one in.  If it blew up, I don't think that's too big a problem as it would just throw paper inside the set, right? 

Yeah, I would be game to just do a short test to see if the new cap fixed the problem. I just would not leave it on for low time. The cap might blow. If a radial leaded cap, the top will just blow up, so as long as nothing is above the cap you should only have a fire cracker pop.

I saw many 22uf 50V and 100V caps from US sellers on ebay. 10 pcs for about five bucks including shipping.

[dhouston]

I saw many 22uf 50V and 100V caps from US sellers on ebay. 10 pcs for about five bucks including shipping.

Here's an even better deal and the seller is in Graham, Washington.
http://www.ebay.com/itm/22uf-22mfd-50V-Electrolytic-Capacitor-25-pcs-RADIAL-leads-USA-Seller-/271908907547?hash=item3f4f08aa1b:g:2cgAAOSw~gRVhyOG

[bkenobi]

Way more than I need, but sounds like the quickest way to get the part.  good call!

[the other steve]

Or, since you are proposing to be quick with the trial, maybe 2 x 47uF in series:

RadioShack 47uF 35V 20% Axial-Lead Electrolytic Capacitor
Catalog #: 2721015
$1.49

As many of us old-timers know, it ain't all that big a bang, anyway.   

Steve

[bkenobi]

I have 47uF in my box too (at least 1 if not 2)

[bkenobi]

So since circuit design was a long time ago for me, I asked google and was told that when I take 2 47uF caps in series, I get the equivalent of 1 23.5uF cap (close enough) and can use 25V (35V would be fine).  So, if I have 2 47uF caps in my stash, I can at least test things before wasting $3.   

[dave w]

So since circuit design was a long time ago for me, I asked google and was told that when I take 2 47uF caps in series, I get the equivalent of 1 23.5uF cap (close enough) and can use 25V (35V would be fine).  So, if I have 2 47uF caps in my stash, I can at least test things before wasting $3.   

If in series, your voltage tolerance doubles, so if you have the room just use the two 47uF. 

[Brian H]

One thing to remember.
Unless you have a matched set of 47uF capacitors. The DC voltage across them will not be equal.
One will have more than half the DC across it and the other one less than half.
As a test I would give it a good old fashion test.

[bkenobi]

If I have 2, they will be from the same vendor.  I know I have 1 22uF/35V so I may just put that one in and see if it pops.