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*** Leo A Capaldi ***
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3,611 Posts
Discussion Starter · #1 ·
Hello all,

My hardly used ARC Air powerbase is not working anymore. I am looking for people who have suffered similarly. The pcb is marked V0.6 14/12/2015. The unit has worked faultlessly several times with the same power-pack but now seems mortally wounded after a period of about a year without use. Have tried holding down both pairing buttons when powering up.

Symptoms:-------------------------------------------

When I plug in th power-pack there are sparks at the connecto. This is the only power-pack I have ever used with it and it is still producing a steady 15 volts.

Red Lane has full power, Green Lane has no power.

The pairing lights both come on with power-up but then go very dim and then the red one lights fully (no controllers are on)
Pressing the pairing buttons has no effect and attempted pairing shows no response.

Cannot connect from mobile device App.
No charred/damaged components visible under the hood.

Large capacitor has 15 volts on it.

Powerbase is isolated from track and I have now unplugged the internal white connectors for the rails and sensors.
 

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novice jazz player &
Joined
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6,269 Posts
These units tend to be very reliable so sounds like you have been unlucky.

My two thoughts are:

1/ possibly the 3.3V internal regulator is failing and shutting down (would explain the dimming of the LEDs)
2/ any DFU firmware update involved?

The voltage would be easy to check if you have a DVM.

If you want me to take a look please send me a PM.

c
 

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novice jazz player &
Joined
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6,269 Posts
It might be worth checking the narrow track just below R17 for potential conductive debris - from the image it might just be shorted to R17 which is the current sense resistor for one of the two lanes. If I remember correctly the narrow track drives one of the brake pMOSFETs.

Also would be good to make a close visual inspection of Q1, that is the accompanying nMOSFET providing motor drive for the same lane. Does it show any signs of overheating? and is there some further debris immefiately to the left?

c
 

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*** Leo A Capaldi ***
Joined
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3,611 Posts
Discussion Starter · #5 ·
Thanks Dr_C. Q1 is on the red lane side and looks perfect. Q3 on the green side has sort of flux like contamination around the top connection (cleaned it up). I removed the bit of swarf from near R17 but no improvement. I have lifted the legs of Q7 (Green Lane driver), it has a short between drain and source. A piece of the package at the gate leg has come away but I don't know if that was my clumsiness or if it was cracked before I unsoldered it. The unit is still not working. The metal cans of C15 and C27 are getting quite warm. Output of U4 is 3.3 volts.
Replacing Q3 looks too challenging and I can get a replacement from Jadlam for 35 pounds so no point in pursuing this any further. I'm only hesitating as I am wondering this is a sign that I should get an ARC Pro... (I don't have any chipped cars and then I'm thinking that ... wait a minute I don't want to open the can of worms about the best digital system !! )

Many thanks, Leo
 

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novice jazz player &
Joined
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6,269 Posts
Amazing price... and it includes two throttle controllers that could be converted for use with ARC PRO if you ever went down that particular digital route :)

c
 
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