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Discussion Starter · #1 ·
I don't have a lot of luck with power bases..I won't bore you with my past history with them, but it does go back awhile :rolleyes:

This morning I hoovered my track because (hopefully) we're going to be racing tomorrow...after I hoovered it I turned it on and the PB went into overload mode (red light on)...so turned it off and went round the whole track to see if I'd dislodged something and it was shorting the track, nope, not a thing to be seen. So turned it back on and it went straight back into overload mode...but this time the PB let the smoke out :oops:.

We'd raced on Sunday with no issues, I didn't use the track yesterday so can't blame anything there...after removing the PB I put the meter across the rails and no shorts (I do have bridge wires across some pieces and thought I may have dislodged one somehow with the hoover).

So, can some kind soul identify these 'ex' components and shed some light on why this may have happened...I do have a spare PB and I'd hate for it to happen to that one as well.

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Many thanks in advance

Cheers 🍻

Neil
 

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novice jazz player &
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Hi Neil, sorry to hear the powerbase failed.

Happy to share some info on the components you show in the photos - and will do so after I finish work later today meanwhile some quick questions:

1/ Is the powerbase still under warranty? If so the course of action is clear. If not…

2/ Does the MLCC capacitor labelled C17 look damaged in comparison to C18? In the photo it looks whiter - but perhaps just the angle of reflection?

3/ Now the magic smoke has been released does the powerbase go straight into overload mode in digital? At this stage dont try analog mode.

4/ Do you have a DVM for trying some diagnostics?

5/ If we diagnose the problem would you, or someone you know, be up for some SMD repair work?

c
 

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The only hardware faults I have ever seen with the ARC PRO are occasional disconnection of the 16 way flat flexible cable (FFC) to the top LEDs and buttons and one case of an IC failure in the MOSFET gate drive circuits - i.e. a similar location to where your components appear to have failed.


c
 

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Discussion Starter · #4 ·
Hi Neil, sorry to hear the powerbase failed.

Happy to share some info on the components you show in the photos - and will do so after I finish work later today meanwhile some quick questions:

1/ Is the powerbase still under warranty? If so the course of action is clear. If not…

2/ Does the MLCC capacitor labelled C17 look damaged in comparison to C18? In the photo it looks whiter - but perhaps just the angle of reflection?

3/ Now the magic smoke has been released does the powerbase go straight into overload mode in digital? At this stage dont try analog mode.

4/ Do you have a DVM for trying some diagnostics?

5/ If we diagnose the problem would you, or someone you know, be up for some SMD repair work?

c
Hi Doc,

Yeah, powerbases seem to be my Achilles heel...I have a feeling this ones toast, but I would love to know what caused it.

1/ The powerbase doesn't have any warranty (it is only about 6 months old, but we're not going there)...it's one of the older ones but with the mods done (digital only and grey wire cut).

2/ I take it you mean C27, it's loose, and I think the landing pad has come away from the board

3/ It went straight into overload mode the first time I turned it on this morning...it's been absolutely flawless for the last few months and hasn't missed a beat. I know the overload cut-off has been working properly because I lost a braid a couple of weeks ago and it tripped out until I reset it.

4/ If DVM stands for digital volt meter I do...the board is now out of it's housing because I didn't see a lot of point putting it back together again

5/ That'll be a no at this current time...we're back playing that new game called Lockdown once again 😤

What do D17 and C27 control? They look to be mirrors of C17 and C18.

I did fix the FFC on that other powerbase...but the Bluetooth on that one is shot for certain

All the best

Neil
 

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Hi Neil,

The part of the circuit with the SOIC packaged IC and the dual pairs of D17/C27 and C17/C18 is designed to generate the gate voltages for the four MOSFETs which do the polarity switching for the track data packets.

The IC does two things…

1/ it times the MOSFET switching so that a pair of MOSFETs never acts as a short circuit across the power supply.

2/ It takes the internal +15V and bootstraps the voltage to approx twice the voltage. This is because two of the MOSFETs (the high side ones) need a voltage higher than +15V to switch them on.

The diode/capacitor pairs provide the basis of two bootstrapping circuits.

Extremely rarely MLCC capacitors can fail as a short circuit. I suspect this has happened to C27. It would be interesting to know whether C27 shows as a short circuit with a digital multimeter set to Ohms range?

If this is the cause of the fault… repair would involve replacing C27, and probably diode D17 which obviously got very hot too.

Also, each of the four power transistors should be checked for high resistance between source and drain pins before powering up.

Anyway, that is an outline of what I suspect was the fault, and how it could be tackled. If it was in my electronics lab I am 100% we could get it running again.

c
 

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Discussion Starter · #6 ·
Anyway, that is an outline of what I suspect was the fault, and how it could be tackled. If it was in my electronics lab I am 100% we could get it running again.
Hi Doc,

One of the guys who's meant to be coming round racing tomorrow has recently been sending bulky items (bike exhausts) to the UK and the like for reasonable amounts...I'll have a word with him and see if he can send electronics back to UK...if so, and you're in agreement, could I send you my collection of powerbases for you to have a play with? :unsure:
 

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Sounds like a plan… lets follow up by PM.

c
 

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Discussion Starter · #8 ·

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Above faulty powerbase showed the MLCC as a short circuit and diode ES1D as an open circuit (i.e. no junction voltage)… so both needed replacement…

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Photo 1: Track waveform before replacement of MLCC and ES1D. Its lost its squareness - a high side MOSFET is not being switched on correctly.

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Photo 2: Track waveform after replacement of MLCC and ES1D - all looking good.

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Photo 3: Some hand soldering came in handy ;)

c
 
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