# Hi Guys, I Need Some electical Diagnostic Help



## DR. SLOTZ (May 25, 2015)

_Stayed up all night pullin the rest of my hair out, attempting to re-build some T-Jets and old school afx chassis. I TARN-Xed all my chassis, washed em up good and dryed em. Install all new ARMATURES & Parts, But They Only spin out at a low rpm. Triple checked Arms, continuity. I never seen this befoe. Got the Arms from 3 different suppliers, as well as the brushes. I've been doin this for 35 years and never seen this before. I'm Baffled Beyond Belief .....ANY IDEAS ????_


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## slotcarman12078 (Oct 3, 2008)

If you have a variable power source, check it wasn't turned down accidentally. Check for a dirt build up on the inside of the shoe hanger plate (between the plate and the chassis). Cleaning the visible part may have messed up the contact patch). Check for tarn-X build up on the top of the brush springs. Check for tightness in the gear train. Other than those, I'm as baffled as you are. :freak:


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## Rich Dumas (Sep 3, 2008)

Many of the NOS T-Jet armatures that you can buy today have defects that may not be immediatly obvious. The armature shaft may not be straight, the stacks can be off center, the commutator can be tilted, off center or warped. I have even seen commutators that have unequal segments. You could try a 2 lamination Dash arm, those are equivalent to a good T-Jet arm. Sometimes you will get a gear plate that is out of alignment, that causes the armature to be tilted and the gears to mesh poorly. The armature pinion can be too close to or too far away from the idler gear and the drive pinion will not be lined up with the crown gear.


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## dlw (Aug 17, 1999)

I have some thoughts, but I need to see the chassis. Can you post a pic of the chassis (particularly the underside) ,springs and brushes?


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## Bill Hall (Jan 6, 2007)

Pancake 101: Fatigued brush springs?

It's a very common malady, and produces the exact effect you have described. Give them a poke and see if the motor(s) will spool up properly.


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## bearsox (Apr 22, 2006)

DR. SLOTZ said:


> _Stayed up all night pullin the rest of my hair out, attempting to re-build some T-Jets and old school afx chassis. I TARN-Xed all my chassis, washed em up good and dryed em. Install all new ARMATURES & Parts, But They Only spin out at a low rpm. Triple checked Arms, continuity. I never seen this befoe. Got the Arms from 3 different suppliers, as well as the brushes. I've been doin this for 35 years and never seen this before. I'm Baffled Beyond Belief .....ANY IDEAS ????_


*From what I am reading here ... your saying that you have the same issue with multiple chassis now post clean and prep correct ? Also you say that atleast 1 is an AFX chassis as well and the SAME issue exists for it as well ? IF SO then the simple parts swap or tweak is not as likely to be a fix ! *
* Making an assumption that the chassis are actually good ... I may look toward other issues I.E. power transfer via supply , track or wire , or controller ! But that is my thoughts based solely on the assumption you are talking about multiple chassis and platforms ! *

*Good luck ! Bear :wave: *


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## cwbam (Feb 8, 2010)

Some Great ideas!

try to keep a couple chassis that work well and leave alone
Change only 1 thing/part at a Time
follow the electrical path


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## dlw (Aug 17, 1999)

Dr Slotz, got any pics of the chassis? It would really help......


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## Joe65SkylarkGS (Feb 15, 2010)

If you can't get one single chassis to run like it should, I'd say try a different power supply or controller. No reason I see why they shouldn't run good. You did the best job cleaning em up just like anyone of us would do.


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## Rich Dumas (Sep 3, 2008)

I suppose that you did remember to oil the armature shaft holes, especially the one in the base chassis? Pancake cars are fussy about oil.


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## slotcardan (Jun 9, 2012)

.......


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## alpink (Aug 22, 2010)

with standard carbon based copper brushes it mught be best to "cook" or burn the oil out/off them.
I use a locking tweezer to hold the brush by it's sides and put a flame to it with a cheap lighter or even my mini torch, depending on what is closest at hand.
just the very tip of the flame.
the brush will spit off little fire trails. when it begins to glow, turn bright orange, it is free of all contamanents and ready to be allowed to cool.

under no circumstances should you put the hot brush in tha cahssis.

some will claim that heating them in that way is destructive, but my cars always run much better after that brush treament and that is proof enough for me.

this advice is only for pancake chassis , not inline.


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## Grandcheapskate (Jan 5, 2006)

Over the past two years, I cleaned all my pancake chassis with Noxon 7. And here is the advice I give to you - MAKE SURE YOU GET IT ALL OFF!!

If any of that stuff remains it will greatly reduce the electrical transfer. I had some cars not work at all because some residue remained. If you can, put the whole chassis into an ultra-sonic cleaner; however, don't do this if you leave the chrome hubs on. Otherwise, scrub the chassis down with warm water and a toothbrush - then blow it dry. You may still have to scrape the top of the brush springs because the cleaner gets in there and it's hard to get it all out.

Joe


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## Rockclimber (May 10, 2021)

DR. SLOTZ said:


> _Stayed up all night pullin the rest of my hair out, attempting to re-build some T-Jets and old school afx chassis. I TARN-Xed all my chassis, washed em up good and dryed em. Install all new ARMATURES & Parts, But They Only spin out at a low rpm. Triple checked Arms, continuity. I never seen this befoe. Got the Arms from 3 different suppliers, as well as the brushes. I've been doin this for 35 years and never seen this before. I'm Baffled Beyond Belief .....ANY IDEAS ????_


There are many things that have been mentioned here by others. Here is some more things to check. New arms / after market , the shafts may be larger diamature therefore they fit tight in chassis holes. Friction is a slot cars worst enemy. Check free spin with out the magnets in the chassis. Feel for any gear grind , wheel rub , put the body on check for tire rub, etc. Next go to the electric part. Check pickup shoes /springs hangers making sure all contact points are clean . Brushes are cheap always use new brushes and springs. Stretch the spring gently to increase brush tension. Do this using a toothpick and your finger nails. Clean arm plate using ba pencil eraser removing all carbon build up. . Next oil all friction points, gears, axels but be very careful with the bottom armature hole . Over oiling will kill brushes and performance .


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## Milton Fox Racing (May 27, 2014)

Welcome to boards @rockclimner ! Hope you share more about your current and previous track biulds, stable of slots and racing experiences.


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