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shadow_rusty

Ssd Pb4 Issues

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Hi, I'm currently having issues with my pb4 shutting down if I try to run 2x Autoart Lambos and 2x Scalextric Jags at once.

Any 3 are ok, but 30secs or so after the 4th car joins, the pb4 shuts down.

 

Should the pb4 be able to handle those cars?

Should I be taking it back under warrenty?

 

 

Thanks

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4 car powerbases have power issues and imo should be taken off the market as they tend to turn people off digital with their issues. The only thing a 4 car pb is good for is Id'ing cars or keeping the power supply for a 6 car APB. I would recommend saving some dollars and get a 6 car PB as they work much better and also gives you the option of switching the PB to analog mode so you can drive cars without chips

Edited by Johnsxr8

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I agree with johnsxr8, 6 car apb is da bomb.


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Well aware that they are inferior to the pb6 as my brother has a pb6, but at this stage, I can't afford the $250 outlay for a pb6...

My pb4 is only 2 weeks old, so is well and truely covered by warrenty...

 

Nowhere can I find any reliable info on what sorts of cars and combos should be supported by the pb4.

Nor can I find reliable info on car current draw for the Autoart cars...

 

I have seen mentioned that the pb4 has a 3amp limit (power supply is 4amp though) and that there is rumored to be a pb4 pro in the pipeline...

I do know that there is significant power problems with the pb4. Most evident is the power surges you get when 1 car deslots, the others gets a 20% boost, and this happens with only 2 cars on the track too...

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Should the pb4 be able to handle those cars?

Should I be taking it back under warrenty?

Yes and yes. At worst you should only see a slowing down of cars as you put more on. If possible, it would be worth testing with 4 different cars and testing your 4 cars on another track.

 

Check the chip installation in the AA cars to make sure there's no shorting with wires touching where they shouldn't. Also vacuum the track well to make sure there'es no bits of braid causing intermittent shorts.

 

Chris

Edited by chris99

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Any 3 cars will run all day long...

So I know that all the cars and the track pieces are ok...

 

Sounds like I'll have to steal my brothers pb4 for testing...

 

I do know that the apb has current checking, and will shutdown if too many amps are drawn for 3 secs.

I can only assume the pb4 has a similar circuit...

 

$250 includes the second power supply in the price.

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Yeah if you can borrow another PB4 and test it would be the way to go. Keep in mind that you already have a power supply from your pb4 that will work with the APB so i would only buy a 6 car APB with 1 power supply should save you around $50 or even more


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hi. I recently had a 6 car base repaired by the distributor (SMS). During a conversation with the guy who fixed it, I was told that some engines run too "hot" (no idea what that means) but he implied it would cause safe mode. If your pb can't run 4 scalextric cars get it repaired under warranty.

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Sounds to me like one of the power stage MOSFETs is starting to fail. I would just get it changed, normally they drive 4 cars without problem. Even when working properly they are pretty rubbish.


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Safe mode on the PB4 can be triggered with the incoming supply dropping below critical level. If there are too many cars, and the PSU cannot deliver the required voltage, then the PB turns off power (actually, the CPU resets and then locks out).

 

Equally, there is a bunch of voltage droppers on the power input to the PB4. These could overheat, but with the huge heatsink on them for the newer PB, this issue is almost eradicated.

 

It doesn't sound like a MOSFet issue (though it is possible) as a failure in this case will likely take a period of time to recover as the over-heat is dissipated. And you'd also likely have on-going faults, too, if a failed MOSFet.

 

Try borrowing another PSU and testing with that and see if its better. But lets be honest, 4 cars on the PB4 with 1 PSU has always been pushing it - especially on the GO Go go!

 

Ian

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Thanks for that info...

I have multiple power supplies, just none of them have the right plug at the moment... :angry:

 

I think I'll borrow my brothers PB4 and his Toshiba 15v 5a power supply and do some testing...

Might end up getting a new power plug and using my 13.8v 10a supply...

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I am pretty sure it has to be a 15v input into the Powerbase for it to run and even if the power supply has 10 amps and you were to have something ontrack that could draw 10 amps from the power supply it would probably fry the pb4. Owners of the old 6 car powerbases used to ship them off overseas to get them upgraded to handle adjustable voltages and high amps (Simple-h mod) and i have also done Riko Rockets high power mod for the APB

 


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There is a circuit inside the PB4 which reduces the incoming voltage by about 2v, then other losses drop about another 1.5v, giving about 11.5v on the motor. 13.8v is close, but by the time it loses the 3.5v, you'll be only at about 10v on the motor. Moral - either keep the 15v PSU, or make some mods to keep the motor voltage right.

 

The PB4 has a 5 Amp fuse on its input - yes, you can blow it which requires a repair, but the internal CPU overload protection usually kicks in before this fuse blows. So as long as there are no other PB mods, a larger power PSU is unlikely to cause issues if its properly managed environment (ie no-one adjusts the PSU voltage lots higher!)

 

Grabbing your brother's Toshiba PSU is the best first test.

 

Ian

Edited by MIH
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Ok, so there are definately issues here...

 

Turns out that I had a 5a Toshiba 15v powersupply at home all along...

It sits on 15.3 volts at idle, and 15.1 volts under load, so that's all good.

 

4 cars are averaging 2.2 amps when all are on light throttle, but once the throttles are opened to approx half, and the load cracks 2.5amps, the pb4 goes into overload...

 

 

I'll be getting my brothers pb4 on the weekend to confirm if his also goes into overload at 2.5amps.

If it does, then it's a design 'flaw', er I mean decision by scaley...

If it doesn't, then it's back to the shop for warranty it goes...

 

Edit:

I also tried my 13.8v 10amp supply, and whilst there was about a 5% drop in speed, all the same issues were still there...

Edited by shadow_rusty

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The rule of thumb is 1 amp per standard car when fired from standing start. Cruising is normally about 1/4 amp for a standard Scalextric motor. Many meters are too slow to give you the true current peaks, so its likely you'll not be seeing that.

 

How many LCs do you have? Each one takes over 1/2 amp as the car travels over it (whether or not changing lanes) for about 1/2 second. With lots of LCs and 4 cars, its surprising how often that high current is drawn. All of it goes through the PB. (And a quick spark/short when crossing a XLC or switch track can also peak the PB)

 

I'm not saying that your PB is not a bit too touchy, but the PB4 is targeted at the entry-level 3 car set, without any significant additional track/changers, PLGs or lap counter. Theoretically it should handle it, but reality is different.

 

Ian

Edited by MIH
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I only have the standard 2 lane changers, and I'm using the standard track layout for all of the testing.

Currently no crossovers on the track...

 

And yes, I agree that the meter is slow...

 

I won't be getting the second pb4 till the weekend, and I'll try to get my other multimeter as well...

Too bad my fluke is missing it's 10amp fuse as that's a much quicker meter than the shitty dick smith $10 special...

Hopefully my RS232 meter will have a higher resolution than the dse one...

 

 

Ian, have you ever disected a pb4 with the intention to see where the cpu senses it's current from?

I couldn't see any sensing circuit on it... (http://electricimage...l.ashx#tab21207)

The closest I can figure is that it may be measuring the voltage drop accross R15/R16 via pin 3...

Edited by shadow_rusty

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You are correct with the current sensing as R15+R16, taken into pin3 via filter R17/C4. Its easy enough to work out the expected volt 'drop' as current grows. The high current raises the voltage at pin 3 (into RA4 ADC) from close to zero to about 250mV at 5Amps

 

R5/R21 and U2 watches the incoming [under]voltage.

 

Ian

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Does that mean that if you increase the value of R17, you could theoretically increase the current at which the software cutout occurs at???

 

Also, did you ever get any further on your pb4 pro venture?

http://www.auslot.com/forums/index.php?/topic/13752-moding-pb4-to-handle-6-cars/page__st__20

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No R17 is unlikely to have much affect. Adding another 0.1 ohm resistor to either R15 or R16 will be what you need.

 

That, or change the firmware!

 

Nothing releasable on PB4 Pro yet. I sense there's little enthusiasm for it, and many people who would make the effort now have 2 PBs.

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If current is currently cutting out at approx 3amps, will adding another 0.1ohm resistor make that approx 4.5amps??

Also, as that will increase the load on the mosfets, will it overload them?

 

I'm still interested in the possablility of a pb4 pro...

Even if it does not increased in power, the simple pace car for practicing would be nice...

Also, the id'ing of 6 cars could be useful... Of course, incar pro probably makes that null and void anyways...

Lastely, it's a much simplier package than a pb6 for the kids to abuse... oops, I mean use...

 

Does the pro firmware go some ways to reducing the deslot spikes?

 

Basically, it sounds like it could do almost everything that I would buy a APB for...

Still, I'm probably in the minority there... And I know how many thousands of hours you must spend writing and debugging code as it is...

Edited by shadow_rusty

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When we looked at ways with the old 6PB to increase power we reached the limitation at 3.5A, and the 4PB uses the same drive MOSFETs, so no you won't get any more out of it. Also even at normal use the MOSFETs are likely to fail, they don't have a dedicated drive chip like the APB so their losses are high, internal heating is high, failure is high.

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Boo....

Oh well, that's a pity...

 

Still, I'll have a little more info as to if my powerbase is faulty tomorrow...

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Hmmm, this may solve my issues too...

At the very least it will remove some load off the pb4...

 

How to power the lane changers externally...

http://www.slotforum.com/forums/index.php?showtopic=6625

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Colin is correct. The MOSFets are not driven 'hard enough' to ensure really efficient operation on the PB4. However the Mk 2 and Mk 3 PB4s did make some improvements over the original design. To mitigate this though, is that the 'heatsink' area for these devices on the PB4 is more than 4 times larger than that on the PB6, so there is more cooling capability.

 

Changes in PB4 firmware unfortunately cannot correct the issue of power spikes when the car deslots. This is because there is limited (read poor) voltage management in the PB4 to ensure more constant volts based upon load. It looks like the APB6 has some voltage management under the huge fan-cooled heatsink inside the unit, which should keep the track voltage somewhat equal even when a car falls off.

 

Ian

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