Power Converter

I did some measuring in the WFCO 8955 with an IR temp probe. The bodies of the power resistors get up to 250 deg F, and the bases at the circuit board go to 210. This isn't even close to melting the solder but leads to fatigue cracks in the solder and damages the circuit board over time. I tried a clip-on heatsink and it helps, bringing the base of the resistors down to 180. I wouldn't trust the clip-on heatsink to stay in place in a bouncing RV, so it's not a solution. This particular converter is retasked as my battery charger, so the heatsink should help prolong its lifetime.

Adding to the above info, the subject resistors I have in hand from a 55 watt WFCO converter are labeled "10W1K5J" which I assume means they are 10-watters. They're in a ceramic case and I'd think they're wirewound. At a high level the WFCO converters are cleanly separated into an electrically isolated power section and control section, connected only by an optocoupler. The problem resistors are in the power section and have no role in the mode selection.

Westend

Those resisters are R2 and R3 in series with a 5 watt 1.5K Ohm value each
They are on the secondary side of the primary switching transformer and look like maybe they are drain off's for two large 820ufd @200VDC caps hooked in parallel. I doubt they have anything at all to do with the voltage sense boost function. Yes I have schematics for most of the units.

Can't remember how many of the WFCO's I have had apart must be more than 50 in the last few years. Regarding converters I see mostly Parallax then PD and Iota then maybe WFCO units and the really off brands.

My comments regarding Electronics Components made in Good Old USA was purely to stimulate conversation. It had the intended result.

My preference are Panasonic FR Series AL Electrolytic capacitors. Excellent quality, small size, low ESR and high temp capable

Wayne Dohnal wrote:
I have worked on 3 WFCO converters and find them to be solidly built using good quality components. Based on what I've seen their high failure rate is due to one design error: A pair of power resistors that transfer too much heat to the circuit board. They are mounted in contact with the circuit board and either one of the solder joints to the board fails, or the board slowly deteriorates at the base of the resistor and turns into a crispy conductor. Then of course there's the other design error of the converter never going into bulk mode as it's installed by the RV manufacturers.

These badly mounted resistors are metal film, I'd bet. As you suggest, getting them up in the air would certainly help.
Are these resistors part of the circuit that has the problem with too much resistance on the output, making the converter snap out of "bulk" mode?

I have worked on 3 WFCO converters and find them to be solidly built using good quality components. Based on what I've seen their high failure rate is due to one design error: A pair of power resistors that transfer too much heat to the circuit board. They are mounted in contact with the circuit board and either one of the solder joints to the board fails, or the board slowly deteriorates at the base of the resistor and turns into a crispy conductor. Then of course there's the other design error of the converter never going into bulk mode as it's installed by the RV manufacturers.

KJINTF wrote:
WFCO
Made in china with Chinese parts
Do we make any electrical / electronic parts in the USA anymore?
Any at all?
Transistors? Capacitors? Resisters?
Any one of them made here?

Sure there are still some on shore mfg.:
Cornell-Dubilier capacitors
Vishay-Dale, Mills, Huntington Resistors(although they do move production around to places like Juarez, Mexico)
Hammond inductors

The question should be are the Asian components as good or possibly, better? Also, has the company building the device, in this case the WFCO converter, elected to use the most reliable assembly or have they chosen to cut costs and build a merely adequate product?

Yes there are some parts still made in America... The ones I know of are not things you would likely deal with but they are things I might some day use if I ever trade in this bucket of bolts an a new Sticks and Bricks.

There is a company, I think in Mississippi that still winds it's own coils and several other parts. They could not find a supplier that met their quality standards.. I know of a few other parts made that way.. Actually own 2 such parts (Microphone connectors) and have E-mailed the guy responsible.

WFCO
Made in china with Chinese parts
Do we make any electrical / electronic parts in the USA anymore?
Any at all?
Transistors? Capacitors? Resisters?
Any one of them made here?

It is a decent converter, in fact a good one, HOWEVER.

WFCO converters are made in China and have the standard China quality rep, In short, they are noted for short life.. WHEN (As opposed to if) it fails, if you still own the RV I'd go with a Progressive Dynamics replacement Made (well assembled) in the USA, it has a much better rep for quality.

jgrimes wrote:
smkettner, yes, I do charge from a Honda 2000i generator at times. When you say to check the voltage at the fuse panel do I simply remove the cover plate and check the voltage by placing the electrodes of the voltmeter on the main breaker terminals - or do I do this at the battery terminals?

Checking at the battery is fine. However it is easy to get a false indication on what the converter is doing because of the voltage drop in the wire connecting converter to battery. Of course if battery voltage is 14.4+ you are good to go.

If you check at the fuse panel you need to check the 12v side where there is a stack of 12v fuses. Breakers tend to be at the 120v side and will let the smoke out of most meters set to 20 vdc scale. The issue is to discover if you are actually getting into boost mode. Many WFCO do not boost when expected.