Gogo best gf700 strangely shut down

[Hurcombe676]

You might not need new controllers. Find out what's wrong first.

Okay thank you so much for all your help, il open the controller up tomorrow and see if anything stands out and il upload photos and see if you can get me back on my quest to having a working bike

 

[Hurcombe676]

I can't physically see anything wrong with this pcb

 

[Hurcombe676]

Very strange I took the controller casing off and checked the MOSFETs which all were consistent and then suddenly now I'm getting a signal when using the red probe on the red power lead I'm getting like 2. 0hms now where as yesterday it wouldn't even register on the red power wire ? Awfully strange

 

[Hurcombe676]

Just checked it again and where as yesterday I was getting no signal from red prope to red battery wire whatsoever, it seems to be climbing was on 2.0 earlier now Its creeped up to like 3.8 , I'm finding this very strange

 

[Hurcombe676]

Now I have 5.2 ohms on all 3 colours with red probe on red wire, yesterday I couldn't get a reading atall, very strange

 

[Hurcombe676]

Now while checking again is constantly dropping right down again ? New controllers needed ?

 

[saneagle]

The climbing is normal because your meter has a battery in it. It applies a voltage when you measure the resistance, then it measures the current flowing through the resistance to calculate its value. There are capacitors across the battery wires, so the meter starts to charge them while you're measuring the resistance. You get a different result depending on which way round you put your probes.

What doesn't make sense is that you had open circuit and now you have a value. It implies that there is a bad joint or intermittent break between the battery connector and the MOSFETs.

Try this: put your red probe on the red battery connector, then measure at various positions along the track on the back of the pcb all the way to the three positive MOSFETs. It should give the short circuit result. If it gives that in all positions, wiggle the wire to see if it goes open circuit.

5.2 Ohms is much too low, it should be 5.2K Ohms. Are you missing the K on your reading?

Your photo is too fuzzy to draw any conclusions. Did you turn down rhe resolution or something?

 

[Hurcombe676]

Sorry to sound stupid when you say track so you mean the pins on each MOSFET or do you mean the long silver bar of solder ?

 

[saneagle]

The red wire is soldered to the PCB. The PCB connects all the components with tracks of tin/lead solder covered copper tracks instead of wire. The tracks are shiny grey metal. The MOSFETs are at the bottom of your photo and the battery connection is to the left. Those tracks have to carry all the power to the motor, so they're the widest ones on the PCB, and they've been reinforced with copper rods soldered to them in some places.

 

[Hurcombe676]

The lower track starts off at at 13.5 far left the middle of track and ends up to 25.7 far end.

If I was just to buy the replacement controllers as this is getting abit technical for me and I don't really know what I'm doing haha, would it just be a case of plug and play and it be back to normal or is there more to it ?

Also being the tech wizard you are could you tell me how to check my throttle on multimeter to confirm it works okay for peace of mind.

Thank you so much for your time and patience it's very well appreciated

 

[Hurcombe676]

I tested along various points of the part circled I'm not sure if that was correct or not

 

[saneagle]

The lower track starts off at at 13.5 far left the middle of track and ends up to 25.7 far end.

If I was just to buy the replacement controllers as this is getting abit technical for me and I don't really know what I'm doing haha, would it just be a case of plug and play and it be back to normal or is there more to it ?

Also being the tech wizard you are could you tell me how to check my throttle on multimeter to confirm it works okay for peace of mind.

Thank you so much for your time and patience it's very well appreciated

Once we established whether thr MOSFETs are OK, the plan was to check out everything else. If neither motor was working, there must be other problems, so new controllers might not solve it.

Generally, you have to do some wiring when you fit new controllers, but if you buy replacements specifically made for your bike, they'd be plug and play unless there was some update or something like that.

When you're doing the measurements, you're giving numbers, but not units. The units matter! maybe show a picture of the display if you don't understand the units.

if you look at the photo of the display from when the probes are in the air, it says 0.L M Ohms. The L must indicate open circuit and the M Omega is the units being measured meaning megaohms.

 

[Hurcombe676]

The controllers were from the manufacturers website for This model and looks identical so I'd hope so.

Okay sorry I'm a plumber I'm totally rubbish with electrics haha water and electrics don't go well together.

When I watched a video earlier on the MOSFETs it stated what was what but I have no clue how to do it as it don't show on the PCb which is which. The MOSFETs are all 3 pin is there a specific way to test these, once again thank you so much for your help

 

[saneagle]

The controllers were from the manufacturers website for This model and looks identical so I'd hope so.

Okay sorry I'm a plumber I'm totally rubbish with electrics haha water and electrics don't go well together.

When I watched a video earlier on the MOSFETs it stated what was what but I have no clue how to do it as it don't show on the PCb which is which. The MOSFETs are all 3 pin is there a specific way to test these, once again thank you so much for your help

You test MOSFETs the way I explained above by measuring the resistance between the motor wires and the battery wires. Forget all that stuff the "experts" show you on Youtube. It's unnecessary and too complicated.

As I sit here now, the results of your tests are unclear. Please do the test again and write down the results along with the units if you want to proceed with diagnosis.

 

[Hurcombe676]

Theese are the result I got with the units on the controller 1.

Red probe to red battery and black to blue it came up as 9.24 m
To yellow was 9.28m
Green was 9.33m

Red probe to black on battery connector
Blue 7.62k
Yellow 7.71k
Green 7.64 k

Controller 2 has 7.62k on all 6 tests

 

[saneagle]

Theese are the result I got with the units on the controller 1.

Red probe to red battery and black to blue it came up as 9.24 m
To yellow was 9.28m
Green was 9.33m

Red probe to black on battery connector
Blue 7.62k
Yellow 7.71k
Green 7.64 k

Controller 2 has 7.62k on all 6 tests

9.24 Megaohms is not a value I'd expect. It's a very high resistance. MOSFETs don't normally go like that. It points more to a break between the battery wire connector and the track that goes to the MOSFETs. If it showed 0.L, it would be more believable. If your fingers touch the probes when you measure an open circuit, the meter will measure your resistance from one hand to the other, which would give a result like you're getting. Are your fingers clear of the metal on the probes?

Can you measure again those three results but with the red probe on the reinforced track that runs across the pcb, where you measured before (photo in post #51), and put the black probe on each of the three motor phase wire connections? That will bipass any breaks in the track or the battery wire.

 

[Hurcombe676]

My fingers could of been touching yes, very fiddly to do haha. Il put it on a worktop surface when home and do it again and also what you asked me to do and will take photos to be sure.

 

[Hurcombe676]

Don't quote me on this but I read on a few various sites online that if it's showing less than 8k then it's damaged is this correct ?

 

[saneagle]

Don't quote me on this but I read on a few various sites online that if it's showing less than 8k then it's damaged is this correct ?

No, it depends on the MOSFETs. I've seen them as low as 3K. Anything from 3K to 24k can be expected. The more the results deviate from that range, the more you should be suspicious of failure, but the most important thing is that the three should all be the same. If one were 3k and the other two 7k, that would indicate a problem.

The problem with your results is that they're 1000 times too high and all the same.

When you short two phase wires while running, the current goes very high. Effectively, it's a dead short across the battery, so something will blow. That something will be the weakest point, which can be a badly soldered joint, a wire, a connector, the narrowest point on a track, a MOSFET, or anything like that. MOSFETs usually become a dead short when blown, which leads to other problems, like the battery's over-current detection switching the battery off when you try to switch it on. They can go open circuit if say a leg vapourises or something like that, though I wouldn't expect that to happen on all three.

 

[Hurcombe676]

I've just placed PCB on some paper and tested making sure my fingers weren't touching and now getting 0.L