Controller low Voltage in vcc circuit.

H

Hulken

10 mW
Joined
Nov 23, 2022
Messages
20
I got an controller 48-80V 80amp 18mosfet drive.

I got problem with low voltage circuit. Its a typical switch strepdown circuit. With mje13003 and as78l05 an 2.2uf 100v cap, 1 25v 220uf cap, 1 16v 220 uf cap.
The 5v is getting 1.5V.

The meashure is done with only battery in and nothing else connect exept vcc power on.
The mje13003 was first at 6v on VOut. I changed resistance from 100ohm 1w to 200ohm 1w and now got 7V out. So 7v in and 7v out.

Further I got 7V in to transistor as78l05 but here is where The voltage drop out, and in circuit 5v+ it shows 1.5V.
I have spareparts and different capacitors ceramic/film/electrolyt etc avalible is there a better choise to use in circuit?
Is there a better choise on caps to use?
I did change some caps with same value but these are small and it could be possible they got damage from heat with solderering.

Anf one more thing I did put The selflearn wire when 60v battery was connect and now i hot 48v connect when troubleshoot.

Please advice on caps and if theres better ones to use.
And whats to be the most logic part to fokus on.
I got an fluke 177 to take numbers from.
 
Is it right to assume the 7805 is The problem? Or capacitorors?
Got alot of components with same circuit but 220-5v.
The 2.2 uf 100v, and 25/16V 220uf alu electolyt caps caps. I personally think its just set to be low cost. And would maybe be good to use higher quality ones. What is the important function to consider in replacing.
The volt and capicitance should only be higher but filter out noise the same?
 
My guess would be something on the 5V rail failed and is pulling the voltage down.
Do you have a way to measure the current? You can measure the voltage across the 200 ohm resistor and calculate.

When 7805 regulators fail, there is usually zero output.

If you leave the power on for a while, you can feel around and look for something that's getting warm.
 
fechter said:
My guess would be something on the 5V rail failed and is pulling the voltage down.
Do you have a way to measure the current? You can measure the voltage across the 200 ohm resistor and calculate.

When 7805 regulators fail, there is usually zero output.

If you leave the power on for a while, you can feel around and look for something that's getting warm.
Click to expand...

Thank you.
I think i found one possible problem. There is an Rectifier that dont pass diode test (shorted) with markings M7.
I got some to change it.
 
Sometimes you get a misleading indication when the part is in circuit. First try lifting one side from the board and test again.
One trick I've used before is to backfeed 5v from a small bench power supply limited to around 100mA and see what happens. If there's a short downstream, it will pull the voltage down. If the 5v stays happy and isn't drawing too much current, the problem is with the regulator.
 
fechter said:
Sometimes you get a misleading indication when the part is in circuit. First try lifting one side from the board and test again.
One trick I've used before is to backfeed 5v from a small bench power supply limited to around 100mA and see what happens. If there's a short downstream, it will pull the voltage down. If the 5v stays happy and isn't drawing too much current, the problem is with the regulator.
Click to expand...


Ive changed the rectifier but must have damage this one. Because now i se 6.5v go trough rectifier and minus -6.5 go back. So the 7805 is getting 6.5 and leak 1.0V or deliver? So posibly 6.5v comes to 7805 and another -6.5 v should cancel out. And should be =12-13V to regulator 7805 So the it can drop it to stable 5V. An rectifier should not let trough any voltage at all in one way not minus and not plus?
Could I be on track.
Nothing gets hot, so it indikate that there is to low voltage or something else that affect the switching

I will try your metod if its not solving anything?
Will try again later.
 
Simple question. Im modifying an kinese ebike controller and have a question about the vcc and its function.
The controller have an wire to put direct on battery pole plus it goes to vcc and power on the controller this isnt very practical.
The question i have is this only an signal to power on or is it current drawn from vcc to orher circuits?
Why i ask is simply that i want to wire to an on/off switch (ignition key) so can I put a small signalwire from vcc to ignition key and back to battery + circuit without any conserns about current flow?

Thanks
 
The VCC line typically draws around 100mA max, so you can use a key switch or small switch to turn it off. You can keep the main battery wires connected to the battery when it's off. Best to disconnect the battery also if you plan to store it for a long time.
 
fechter said:
The VCC line typically draws around 100mA max, so you can use a key switch or small switch to turn it off. You can keep the main battery wires connected to the battery when it's off. Best to disconnect the battery also if you plan to store it for a long time.
Click to expand...

Thanks. I was planning to use one cable with 7 signal wires for ignition, trottle and speed switch.
 
You must log in or register to reply here.
Back
Top