I have a Trace Inverter model U2512SB that seems to have a problem. I am getting good output voltage of 120v. My problem is with the Hz. Instead of it putting out around 60hz., I'm getting around 17Hz.

I was able to locate an owners manual but saw nothing related to adjusting of the Hz.

Does anyone have a tech manual or might have had a problem with a low Hz. rating on their unit?

If I'm not able to adjust this setting, then I guess it's time for the bone yard.

It sounds like the oscillator is bad; it's very unlikely the frequency can be adjusted. Time to get a new inverter.

Bill, I see from the owner's manual that the frequency is "crystal controlled." If that unit is as old as I think, it might still have a discreet crystal somewhere on the PCB.

Check the freq at this point on the PCB. The crystal often has freq labelled...BTW I have hundreds of old crystals left over from salvaging old CB radios, ham and early computer power supplies. Never know, find out the freq and we might have a crystal for it.

what are you using to measure the frequency? The old inverters are usually "modified sine wave" or stepped square wave output. Some frequency meters get screwed up by this type of output. Do you have an oscilloscope to look at the output and do a frequency measurement.

Most crystal controlled inverters use crystals in the 3 Mhz range.

Manual says it is a modified sine wave so ditto for
Ed's comment: check with scope, freq counter may be confused.

I recall 3.58 Mhz being a common crystal.

Hope we can get thing running right... at 25 kW it won't be cheap to replace.

2.5KW - still not cheap. If it's the crystal, hopefully something available will work.

quote:

Originally posted by MWrench:
what are you using to measure the frequency? The old inverters are usually "modified sine wave" or stepped square wave output. Some frequency meters get screwed up by this type of output. Do you have an oscilloscope to look at the output and do a frequency measurement.

Most crystal controlled inverters use crystals in the 3 Mhz range.

I am using a "P4400 Kill A Watt"



I do not own a oscilloscope.

Perhaps I don't have a problem after all? I ran my generator and it read around 60Hz @ 120v and then I checked the current at the garage and got the same thing too - so I know my kill a watt unit is working. I guess that what you're telling me is the modified sine wave could be screwing up my kill a watt meter in the Hz. range.

My remote control panel for the Trace Inverter is reading the same thing as the kill-a-watt meter. I would think that the remote panel would have been compensated for the modified sine wave.

The last time I used an oscilloscope was in my autoshop class from the 80's.

You may not have a problem. The Kill a Watt may be confused. Have you tried it under load? You could safely run resistive loads like light bulbs or heaters, (they don't know DC from AC) that may smooth the output enough to satisfy the Kill a watt and get a normal reading.

A 'scope would tell.. not that common these days as you said. I got my Tektronics in the mid 80's... (I think it still works but I used it mostly for radio work back then.) Maybe you can find one around there.

As I've said before, I continue to be amazed at how smart many of you are. Heck, I have trouble trying to find the 'on/off' switch sometimes.
Humbo

Bill if you connected any small wattage light bulb to the inverter, 10-40 watt, if the inverter was indeed running at 17 Hz, you would see the bulb flicker. If you got a LED type it would show the flicker even worse. If the voltage is 120 VAC then the bulb should be at full brilliance regardless of the frequency.

Don't look directly at it, just look out of the corner of your eye.

I don't know how many of you guys remember Canada when they had 25 Hz power, was very annoying because you could see the lights flicker.

I could probably fix it if it is running at low frequency. Will have to be after I get back from the race event in Texas next weekend.