Loose wires in ST head

[Dave]

Has anyone have these loose wires in a chinese ST head?

http://listerengine.com/coppermine/thumbnails.php?album=126

[Dave]

Picture of wires test

[Technonut]

I'm not sure about the ST,  but the 2 clipped wires in my Croatian SKG gen-head were there to run straight 120V at full rated amps from the voltage regulator. The SKG was factory setup for 120/240V. I switched two wires going to the voltage regulator with the clipped ones since I needed straight 120V full amps to my 120V inverter. I also had to strap two leads together as shown here: http://utterpower.com/genhead.htm.

[phaedrus]

Loose wires? UUUmmm, not exactly loose to start with, but the series wound 4 pole rotor of an ST 5 that I have had splices that were not soldered. It worked ok for a while, but when I switched the load-bank on to bring the machine up to about 4 kw the output went to zero after about a minute – one of the twisted-wire rotor splices got hot enough to soften the cooper so that the wires came loose and a little piece broke off. That didn’t do any mechanical damage, but that was a matter of luck. I suppose the spike that must have formed in the rotor when the break occurred may have damaged the AVR, but I won’t know about that until I either replace the rotor or repair it – and I’m waiting for the vendor to either authorize a field-fix by me or replace the thing.

Meanwhile I'm running a spare that has a crappy AVR, bummer!

[ronmar]

The two wires that carry excitation current from the doghouse to the brushes on my ST-5 were quite long and not properly secured.  I missed this in my initial inspection and they were hanging down into the area between the brushes and the rotor and caught on one of the terminals that carry the current from the slip rings to the rotor windings.  It ripped this terminal off the rotor as well as parted the loop of wire.  Minor damage, fixed in about 10 minutes, but I was lucky.  While I had the thing apart for sealed bearings, I soldered ALL electrical connections and crimped-on terminal lugs to their wires.  This only takes a few minutes with the end cover off the generator housing.  It is not a question of IF the soft, low budget Chinese crimp lugs will fail, but WHEN they will fail.   

[Doug]

Could you fellows please post the brand names on the heads you had trouble with, vender and what you paid for the heads?

This kind of information canl help other decide what and from whom they should buy.

I think it would be wise for anyone buying an ST head to strip that as well as the Listeroid. These aren't the first complaints we have heard about STs.

Therefor a quick inspection is probably in order, replace the bearings with quality 2RS or 2Z, check the fit of the end bells and shaft repair if needed new bridge rectifier and or AVR, check solder joints and sleaving, recoat winding with Glyptal 1201A. LAst step hi-pot test at 2 1/2 rated voltage or 1000V meggar.

Trouble is this costs, now we are in the territiry of buying a quality head in the first place if you can't do some or all this yourself.

Doug   

[ronmar]

Mine was a PS ST-5 with the doghouse(newer version does not have the doghouse).  Other than the wires from the rectifyer down to the brushes being excessively long and not secured up in the doghouse with a ziptie, it was otherwise very good.  It spun true and gaps between stator and rotor poles were consistent around the circumference.  I think the soft crimp-on lugs will be found on most all af the Chinese ST heads, regardless of who they are imported thru.  Many people run them as-is, but I am a little pessimistic so I soldered mine.

Ron