Federal STH10A Troubleshooting Questions

[stevecast2024]

Alright... I'm working on a project for a local fire company. Their STH-10A has not functioned for the past 2 to 3 years. I am guessing the motor is shot based on some troubleshooting that I did. When checking continuity, I am showing open circuits between all phases going to the siren. I went of to check the siren and found the chopper locked up. I could not spin it and even putting force into it to break it free, it would not budge. Am I looking at a motor issue here, and if so, is it possible to pull and replace the motor without de-mounting the entire siren if I can locate a motor? Any ideas would be a huge help. Really trying to get these guys back in business.

[Archon]

TO check for grounding you need a megamomator and check from each phase to the case of the motor as for the locked up that is probably the bearing sized up on it or the rotor has some oxidation on it that needs to be sanded off if it was in a higher salt area IE by a major road or near the oceans the aluminum tends to get white

[500AT]

A local fire department recently rebuilt their STH-10B, and they had to dismount the siren from the support pole. This is the only way you can safely remove the motor from this unit. However, after a complete motor rebuild, sanding and painting, the siren is as good as new.

[stevecast2024]

Thanks guys. I guess I'll be finding a way to get it down off the platform. The area that I'm in is a litter ground for all kinds of sirens. There are a few sth10s throughout the county that are no longer in service. Parts may be available from those if I try hard enough. Now if I could just teach myself how to rewind the motor... unfortunately there is no money available for this project from the fire company.

[Grasshopper]

Brush and spring assembly from Fed Sig is available; Q-BSA

[holler]

Brush and spring assembly from Fed Sig is available; Q-BSA

He says it's an STH-10A, which means it's three phase. Three phase motors don't have brushes.

[Grasshopper]

Brush and spring assembly from Fed Sig is available; Q-BSA

He says it's an STH-10A, which means it's three phase. Three phase motors don't have brushes.

You are correct about the 3 phase. Fed Sig does not supply replacement parts for that since it is 30 years + obsolete.

It is not uncommon for manufactures to discontinue selling parts for obsolete models or old models of equipment.

It is hard to get parts for many vehicles that are that old correct? Unless a company decides to manufacture aftermarket replacement parts

[holler]

Brushes are still made the single phase STH, since the motor was made by Northwestern Electric and the brushes are used in other applications.

http://www.graphitestore.com/itemDetail ... &curPage=1

The majority of parts on these sirens were not made by Federal and can be tracked back to the original manufacturer for a replacement.

[theroofable]

Brush and spring assembly from Fed Sig is available; Q-BSA

He says it's an STH-10A, which means it's three phase. Three phase motors don't have brushes.

You are correct about the 3 phase. Fed Sig does not supply replacement parts for that since it is 30 years + obsolete.

It is not uncommon for manufactures to discontinue selling parts for obsolete models or old models of equipment.

It is hard to get parts for many vehicles that are that old correct? Unless a company decides to manufacture aftermarket replacement parts

Car manufacturers have to make parts for 10 years. The siren was discontinued in 2006, so an STH10 could only be 7 or 8 years old. (I know his siren is older, but they still made them not too long ago is the point.)

[holler]

Actually I think the single phase STH was dropped whenever Northwestern Electric was bought out by Emerson. Mid to late 90's I think.