Blown capacitors? (Lost 12volt converter power)

[Moho]

Yeah thats a failed electrolytic capacitor.

The "fuzz" is the tissue from a rolled cap design which is the insulation barrier between the anode and cathode. When they fail the anode and cathode basically short circuit, create gas, the cap swells and the tissue insulator is pushed out.

Now depending on how good you are with a soldering iron and desoldering braid (I assume you don't have a desoldering iron). You can just delsolder and replace those capacitors. You just have to match the cap value. For example the biggest one in the photo is a 16v 2200uf Electrolytic capacitor. Most likely there is not a source for those locally, you can get them from places like mouser.com. These caps only cost a a few pennies each.

The key to this is you can't just fire it up once the obvious bad components have been replaced. Once they have been replaced this will give you a more complete circuit to start testing continuity, capacitance, etc.

Now the most likely thing that happened by it being marked fan, keep in mind this is just a guess based on experience, is that it started there with that cap marked fan, the fan didn't kick on causing a chain reaction with heat build up. The obvious units to test would again be the transformer, which can build a lot of heat depending on the design & the items attached to the heat sinks (voltage regulators and rectifier diodes). This is assuming that you had it running and then all of the sudden lost power.

One last thing; 2200uf caps @ 16v and such don't have enough amperage stored to be a concern about being shocked or having to dischage caps.
IF you see any LARGE filter capacitors marked with high voltage (100v plus, which you shouldn't) you MUST discharge them . To discharge a cacitor safely, take a 100ohm, 20watt or so resistor and short the two pins of the capacitor with it. Hold the resistor with a pair of needlenose. Don't do the screwdriver short circuit method tons of people do, it can cause more damage.

[Dale M.]

Can't tell for sure in pic but the 2200uf (big blue one) doesn't look good... Looks sort of swelled from my view... Should be truely cylindrical and have flat top.... And yes capacitor fuzz is not good....

Dale

[zipz71]

You can use 25 volt caps in place of 16 v if there is enough room. Electrolytic caps are polarized marked with a stripe and a negative sign on the body and must be replaced the same way. Make sure they are 105 degree and not 85 (105 are most common). If there are any more the same value on the board replace them also even if they look fine. There is a good chance that caps will fix the problem.

[Moho]

You can use 25 volt caps in place of 16 v if there is enough room. Electrolytic caps are polarized marked with a stripe and a negative sign on the body and must be replaced the same way. Make sure they are 105 degree and not 85 (105 are most common). If there are any more the same value on the board replace them also even if they look fine. There is a good chance that caps will fix the problem.

Not all electrolytics are polarized, but most are. If there is a stripe then they are polarized and thanks for pointing that out and the temp.

[Alfred]

Hi All,

Here's some more pictures:











Thanks for the feedback!

AL

[Moho]

The two obvious caps circled below need replaced. I pm'd you to email the full size pics to me. Hard to see with the scaled down size for forum use. btw the marking for fan is for the connector, not the cap.

[Moho]

Ok after looking at the fullsize pictures below is what I see. The green circled capacitors need replaced. The red circled item looks like an inductor that had heat as well. Post the specs found on the sides of these items and I'll verify the third item is in fact an inductor. I see no obvious heat indications on other items on the board. I would replace those and feel safe enough to fire it up and test voltage coming out of the dc transformer (the big one in the middle of the boardmarked MTRE140-12-?). It will have 110v AC in and DC voltage out. If there are two wires out the voltage shoud be probably 24-36v DC out. If it has three leads out the center lead will be ground and each of the other two will have half that voltage on each one. REMEMBER there is 110v AC curent going through sections of that board when turned on, so don't handle it!!!! Also double check the voltages on the two big brown filter capacitors and discharge if high voltage like I said a couple of posts back before desoldering.



To desolder the capacitors use the pencil type iron you have with a fine point tip, not the gun on the back side of the board. Solder guns have WAY to much heat for pcb's and the copper can seperate from the board or burn through. Also make sure your pencil soldering iron is not more than 35 watts. Make sure you note the side that the vertical stripe is on on the caps and replace them in the same direction. Here is info on how to desolder http://www.mgchemicals.com/downloads/appguide/appguide0805.pdf. Desolder Braid can be purchased at your local radio shack. Also get .032 diameter 60/40 solder while your're there. It will make doing the solder work MUCH eaiser than the normal solder most households have. Most people have the big diameter solder .093 - .125 which is worthless for electronics.

Also here is a Youtube video of desoldering and soldering a pcb http://www.youtube.com/watch?v=WWOx18w23ts Take note of the length of time the soldering iron is in contact with the pcb.

When soldering pcb clean the tip of your hot iron by wiping it on a damp sponge. Make sure the tip is tinned (has shiny solder showing) if not put the tip of the iron in flux, apply solder and wipe on the sponge to tin it. You then apply the solder tip to the pcb touching both the pcb and the leads sticking through the board. After 1-2 seconds apply the solder to the area where they meet. If it doesn't melt instantly the tip isn't hot enough and remove it from the pcb before you burn through. There should be no need for flux on the pcb because the pads on the pcb will be tinned already. Also remember that most common soldering iron's don't have tip temperature control so don't leave it on too long as they just continue to get hotter and hotter. Only plug it in and heat it up right before you are ready to work. Proper solder joints are like the middle one below...


One last thing if you can't easily get the capacitors and have to mail order 2-3 items, let me know the specs on them and if I have them, I can just throw some in an envelope and send to ya to save ya $5.00 or more in shipping. I have an 8ft long wall with those plastic storage drawer units ceiling to floor of electronic components, so no big deal.

It's a lot easier to replace the components than I am making it sound, just trying to make sure I cover my bases as PCB rework is very different than the soldering most people are used to. Let me know if you hav any questions and good luck getting it going again

[Alfred]

Hi all,

Just an update - I have removed the board from the unit. The two capacitors are 2200uF 16volt, also says CE 85 (degree) c.

But I see no writing on the item believed to be an inductor.

I took it over to Radio Shack the other day, but although the young fellow wanted to be helpful, he didn't know what to do, except told me they do not have those capacitors stocked at the store.

AL

[Moho]

Yeah radio shack is pointless unless you need help picking out a cell phone. I checked and I only have axial caps in that range. I would guess that component (what I thought may be an inductor) is possibly shrink wrapped. Personally I would be comfortable just replacing the caps and giving it a shot.

Prepared you a shopping list below...

2200uf Caps: http://www.mouser.com/ProductDetail/Nichicon/UKL1C222KHD/?qs=QeBbLCJIbegdfn1eBF3HKA%3d%3d
Desolder Braid: http://www.mouser.com/ProductDetail/Techspray/1810-5F/?qs=sGAEpiMZZMt%252biMJH3c40u7O%2fYZE0tl%2f%252b10vvPREox0Y%3d
Solder: http://www.mouser.com/ProductDetail/MG-Chemicals/4870-18G/?qs=sGAEpiMZZMs77WAlHGN5Q5WdRjWSCQ9zFa6JTZjrp9Q%3d

[Alfred]

Prepared you a shopping list below...

2200uf Caps: http://www.mouser.com/ProductDetail/Nichicon/UKL1C222KHD/?qs=QeBbLCJIbegdfn1eBF3HKA%3d%3d
Desolder Braid: http://www.mouser.com/ProductDetail/Techspray/1810-5F/?qs=sGAEpiMZZMt%252biMJH3c40u7O%2fYZE0tl%2f%252b10vvPREox0Y%3d
Solder: http://www.mouser.com/ProductDetail/MG-Chemicals/4870-18G/?qs=sGAEpiMZZMs77WAlHGN5Q5WdRjWSCQ9zFa6JTZjrp9Q%3d

Hey thanks, Moho!

I used your links and ordered them today, and they're on the way - Hope to get them on Thursday. Ordered the solder and the braid, too. Links made it really easy. I appreciate the help!

AL

[Moho]

No problem, the 4000 page catalog can be overwhelming

[chorizon]

Y'all have any ideas as to what blew the caps in the first place?
I'd be pretty interested in keeping my converter from suffering the same fate...

[Shadow Catcher]

American Enterprise is a Hongkong manufacturer sold in the US with a center in Elkhart In. From what I can find they do not have a good reputation and I found at least one individual and know of others who converted their converter to a Progressive Dynamics (quieter more reliable US made). PD's have some over voltage regulation built in.

[Alfred]

Y'all have any ideas as to what blew the caps in the first place?
I'd be pretty interested in keeping my converter from suffering the same fate...

Hey gang,

When I called the manufacturer customer service line the person with whom I spoke told me they no longer manufactured this model, which they implied had some problems, and encouraged me to consider upgrading to a better progressive model, should I decide to change-out the unit altogether. They offered to sell me the upgrade at a discounted price (about $25 savings). They also suggested some of the older phased-out models currently being auctioned on E-Bay (which is where I purchased this one) might be defective, and not intended for retail.

But, I think in this case the root cause is about a year ago I accidentally ran 24 volts through the 12 volt intake connection (I had two small batteries in tandem that I thought were 6 volts each, but then discovered after the fact that they were 12 volts each). It was only for a couple of seconds, which is probably all it takes. The unit made a 'popping' noise, which at the time I assumed to be some sort of internal cut-off, and I immediately unplugged it.

I came back later, plugged the shore power back in, and it worked fine. Never hooked a battery up to it again. It continued to work with no problem over the next year or so. I did notice in the weeks before it stopped functioning that I blew one 12 volt bulb, and the 12volt bulbs in the lanterns were taking on a brownish hue. I had attributed this to normal wear/tear on the bulbs, but now I am wondering if the power wasn't running 'hot'.

So, my working theory now is I probably did some damage a year ago, which was masked by the unit being basically operational, but probably the capacitors were damaged and going, just took them awhile to cut-off completely.

So, hopefully the price of my valuable learning experience this time out will only be the cost of the capacitors. I am going to switch them out this weekend, so I'll keep you posted.

AL

[zipz71]

The pop you heard was the capacitors. They are only rated for 16 volts. Hooking them up backwards will do the same thing. There is a good chance the new caps will solve your problem.