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Author Topic: need gen help....st head  (Read 2186 times)

32 coupe

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need gen help....st head
« on: September 13, 2017, 03:33:51 PM »
i have run my 15kw st head the last few days, a few hours at a time.

this mornimg i am only getting about 90 volts........it has the orginal cheap Chinese diode.

think.it could be the diode ??
i cleaned the brushes and slip rings but no improvement.

fortunately i have a back up for my backup so all is not lost !

thanks for any help or input,
Gary
Metro 6/1 turning a ST 7.5 KW gen head
Changfa 1115 turning a ST 15 KW gen head
Ashwamegh 2/25
John Deere 110 TBL
New Holland TC 30

"I was sitting here reading this thinking what an idiot you are until I realized it was one of my earlier posts !"

38ac

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Re: need gen help....st head
« Reply #1 on: September 13, 2017, 04:03:51 PM »
Gary,
When my ST15 volage went low like that it was indeed the diode/bridge rectifier that caused it.  You can swap the one from your other ST if you need the amps.  Too late now but you can buy a bag of 1050 bridge diodes on E bay for very little I have like 10 spares now..
« Last Edit: September 13, 2017, 04:05:28 PM by 38ac »
Collector and horder of about anything diesel

BruceM

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Re: need gen help....st head
« Reply #2 on: September 13, 2017, 04:51:15 PM »
+1  Put in a decent bridge diode.  Something rated 800V or more is best.  Best to mount the diode with some thermal grease to a metal housing.  I prefer the ones potted in a metal housing for the best thermal conduction. 

Digikey 641-1854-ND ($2.50) is a good choice:
https://www.digikey.com/product-detail/en/comchip-technology/KBPC2510-G/641-1854-ND/3300073
added note- Digikey offers first class mail for small orders, very cheap.

Anything above 800V and 15A or better will be fine.

I've not had the stock diodes last more than 30 hours or so of run time.

I'd also replace the bearings. 

« Last Edit: September 13, 2017, 06:04:09 PM by BruceM »

Tom

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Re: need gen help....st head
« Reply #3 on: September 13, 2017, 05:25:52 PM »
+1 on both the rectifier and bearings. My ST5 now has about 2800 hours on it and other than those 2 items, a connection that came unsoldered is the only issue I've had with that unit.
Tom
2004 Ashwamegh 6/1 #217 - ST5 just over 3k hours.

32 coupe

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Re: need gen help....st head
« Reply #4 on: September 14, 2017, 02:38:06 PM »
thanks guys !
yep, that cured it.
more later, limited net access...

Gary

Metro 6/1 turning a ST 7.5 KW gen head
Changfa 1115 turning a ST 15 KW gen head
Ashwamegh 2/25
John Deere 110 TBL
New Holland TC 30

"I was sitting here reading this thinking what an idiot you are until I realized it was one of my earlier posts !"