Electrolux ERG22 vacuum cleaner pcb fault

[Crystaleyes]

So, I have this Electrolux vacuum which had the batteries revently replaced and now it won't work.

The voltage from the batteries is arriving to the board without problem (+/- 12v) @ CN4 & CN6.
The motor works fine when voltage is applied to FM+1 & FM-1. The switching on and off is made in the negative line between CN6 and FM-1, and all components have been tested as fine apart from a FET.

The problem appears to be that the PHD71NQ FET (Q18) isn't switching when the power button is pressed.

I say this as when I started to connect my component tester to this FET, the motor fired up.

The exact situation was that one clip was on the Gate, and when the second pin was touched to the Drain, then the motor kicked in, nothing was connected to the Source.

Should also mention that there is the 12v on both the Gate and Source pins at all times. Drain connects via a couple of inductors (L5 & L6) to the motor supply.

I don't have the most experience with FETs but seems to me that I need to test the FET out of circuit and work my way back to the power switch if it tests bad.

Does that sound about right?

[momaka]

Re: Electrolux ERG22 vacuum cleaner pcb fault

I don't have the most experience with FETs but seems to me that I need to test the FET out of circuit and work my way back to the power switch if it tests bad.

Does that sound about right?

Not only that, but you CANNOT test components in circuit using resistance test or diode check or continuity when there is voltage in the circuit or a battery connected. ALWAYS remove all power sources when trying to test a component in circuit. Otherwise, you risk doing more damage to the board and also your multimeter (especially the case with circuits with higher voltages.) Also, those component testers are often inaccurate for in-circuit readings, so I don't recommend you use it for that.

So to be sure about the MOSFET... yes, remove it out of the circuit and test it.
If it's an N-ch FET, you should get a diode reading (~500-700 mV range) between Drain and Source when red multimeter probe is on Source pin. Reversing the probes should give no reading (open circuit.) Next, connect black MM probe to Source and touch the Gate pin with the red probe while using diode test. Then move the red probe to Drain. The MOSFET should now be turned on and you should see a low or almost no voltage drop between Drain and Source (as if the pins are shorted together.) If you touch the Gate pin with your finger, that should discharge it and the Drain-Source connection should disappear back into an open-circuit. Note that this test only works for testing MOSFETs out of circuit.
For P-ch MOSFETs, these tests above are the same, but just switch the positions of the red and black probe for each test... or use your component tester, if you prefer.

[Crystaleyes]

Re: Electrolux ERG22 vacuum cleaner pcb fault

Well, actually, now I am officially confused..

The owner of the appliance was hassling so much that I picked up the same model for cheap just to use the pcb until this board got fixed.

I carefully disconnected the batteries before installing it and after carefully reconnecting the battery supply, gave it a quick test and it worked fine.
After screwing the pcb back down into the plastic frame however, the vacuum once again refused to work.

I had assumed that the first fella had perhaps shorted the batteries onto the board, but now I'm doubting that. I don't see how it can be static, as it worked fine after being soldered back together and the pcb securing pins only connect to plastic.
The only thing I can think of are that the new battery pack is somehow causing the damage. That is now two identical (working) pcb's that are now dead!
The battery pack consistes of three 18650 cells which are charged to around 12.5v although the charger is rated at 13.5v.

This is pissing me off now....

Fucking ball-ache!... How difficult can it be to connect a new battery pack?

Cunting fucking thing

[sam_sam_sam]

Re: Electrolux ERG22 vacuum cleaner pcb fault

I had assumed that the first fella had perhaps shorted the batteries onto the board, but now I'm doubting that. I don't see how it can be static, as it worked fine after being soldered back together and the pcb securing pins only connect to plastic.
The only thing I can think of are that the new battery pack is somehow causing the damage. That is now two identical (working) pcb's that are now dead!
The battery pack consistes of three 18650 cells which are charged to around 12.5v although the charger is rated at 13.5v.

What this sounds like to me is that you either have broken trace or you have some bad soldering joint issues and if it is a double sided or more layers than that the trough hole pads might be broken

Here is what I would recommend take a magnifying glass and very carefully look at each and every soldering joint for separation ring or rings or very dull soldering joints and if you find any resolder them

I hope this helps you with your repair

[stj]

Re: Electrolux ERG22 vacuum cleaner pcb fault

look near the screw holes for bad/cracked tracks

[Crystaleyes]

Re: Electrolux ERG22 vacuum cleaner pcb fault

What this sounds like to me is that you either have broken trace or you have some bad soldering joint issues and if it is a double sided or more layers than that the trough hole pads might be broken

Here is what I would recommend take a magnifying glass and very carefully look at each and every soldering joint for separation ring or rings or very dull soldering joints and if you find any resolder them

I hope this helps you with your repair

Thanks fella.

I hope it helps too.

Having a day off it today but shall have a close look tomorrow

[Crystaleyes]

Re: Electrolux ERG22 vacuum cleaner pcb fault

look near the screw holes for bad/cracked tracks

Cheers for the input.

Gonna do that, but am wondering why the same issue would pop up with two different boards? I thought that I was extra careful when installing the battery pack.

Anyways.. as mentioned, gonna get back on it tomorrow.

I'll remove one of the boards and post clear photos of every component.
It doesn't seem too complicated a pcb, in that it clearly has a charge control section and a motor control section.
The failure is that the N Channel enhancement FET isn't switching.

WHY that fecked up is another matter, but hopefully we can find out quickly

[Crystaleyes]

Re: Electrolux ERG22 vacuum cleaner pcb fault

Actually went to an Electrolux authorised repair centre this week and they neither sell replacement boards, nor do they repair them. They suggested that the boards were damaged by poor quality replacement batteries...

Anyways, these boards simply have to get fixed. No option...



Finally got a chance to have a closer look at the circuit, and there is an HT7533 3.3v sot89 voltage regulator (U2) which has zero volts on the 'in' pin.
Tracing the circuit back, it goes to the lower right hand side pin of an sot23 device (Q10) which is marked 'NG1N'. So far haven't managed to find out what kind of transistor this is?
The single pin of NG1N, then connects to an M7 diode (D6) which is connected to the board fuse.

A quick recap as to the situation. The owner bought three 18650 replacement cells and without any shorting, the unit stopped working.

The power from the battery comes into the board at CN4 (+ve) and CN6 (-ve).
The +ve line goes through a fuse and a couple of inductors straight to the motor via terminal FM+1.
The -ve side is switched through button (BT1) and a mosfet (Q18) before connecting to the motor negative terminal FM-1.

Obviously this FET isn't receiving any 'turn on' signal.

That comes from U1, an M2Q5VLC4 (MKE02Z32VLC4) microcontroller, however that isn't reveiving the 3.3v from the HT7533 due to the fact that nothing is coming from Q10 'NG1N'.


Need to find out what the NG1N is?

[Crystaleyes]

Re: Electrolux ERG22 vacuum cleaner pcb fault

Why do I keep getting logged out every minute?


Even writing this I had to log in again...

How can I post photos to show the situation if I get fucked off every 60 seconds!!??!!??

[Crystaleyes]

Re: Electrolux ERG22 vacuum cleaner pcb fault

What this sounds like to me is that you either have broken trace or you have some bad soldering joint issues and if it is a double sided or more layers than that the trough hole pads might be broken

Here is what I would recommend take a magnifying glass and very carefully look at each and every soldering joint for separation ring or rings or very dull soldering joints and if you find any resolder them

I hope this helps you with your repair

Thanks for the suggestions but I don't see how it would apply to two different boards?

The Electrolux shop reckoned it was poor quality batteries although I've never seen this before. Other than that, I can't help but wonder if it wasn't some static charge?

[Crystaleyes]

Re: Electrolux ERG22 vacuum cleaner pcb fault

Trying to work my way back through the circuit with the intention of creating a rough schematic although drawing electronic pcb schematics is far from my forté-

I had thought that the button merely switched on the motor in the negative line, however I have just noticed that yes, one side is of the button at -ve potential, however the other side is at the battery positive of around 12v.

I wasn't expecting that

It might get to the point of just removing components and testing them off the board.

This absolutely has to be fixed...


Once again I've been FUCKING LOGGED OUT!!!!!!!!


SERIOUSLY fucking boring

[Crystaleyes]

Re: Electrolux ERG22 vacuum cleaner pcb fault

Thanks to R_J for identifying the NG1N as a PNP although that hasn't helped me understand any more how the circuit should be working.

The circuit has a three pin HT7533, 3.3v voltage regulator which has zero volts on the 'voltage in' pin.

Following the circuit back it arrives at the emitter of the above mentioned PNP. I would have expected an NPN on that circuit.

I've never fully understood PNP transistors but had always been under the impression that the base must be negative to the emitter in order for the current to flow between the emitter and collector.

So how is a positive voltage supposed to arrive at the 'in' pin of the HT7533 if there is no voltage on the PNP?

[stj]

Re: Electrolux ERG22 vacuum cleaner pcb fault

clean the flux off ffs.
it's leading to q11
ultimatly it probably goes to the button so when you press the button it latches on and the microcontroller probably relaeses it after your done

try jumping the power across it to see if the mcu does stuff under poer.
btw - where is the charger/protection circuits?

[Crystaleyes]

Re: Electrolux ERG22 vacuum cleaner pcb fault

clean the flux off ffs.

Hi mate.

There's not really any flux on the board. All that residue is from where I've been scratching off the varnish in order to read the component numbers.

Didn't get a chance to do anything last night but will have another go after work today.

I had thought about jumping the power... I'll give that a go. Cheers!

[stj]

Re: Electrolux ERG22 vacuum cleaner pcb fault

so it's got conformal coating on it? bitches!
did you connect the charger?
some battery protection circuits latch off untill you try to charge the battery

[Crystaleyes]

Re: Electrolux ERG22 vacuum cleaner pcb fault

so it's got conformal coating on it? bitches!

Yeah, all over it...

did you connect the charger?
Some battery protection circuits latch off untill you try to charge the battery

I hadn't thought of that

Actually, I didn't try connecting the charger perhaps as the battery pack was showing +/-12v when the 'official' motor voltage is 10.8v.

Probably have to do all this tomorrow as have been having 12 hour work sessions recently, but thanks for the suggestions. Most appreciated.

I've changed many battery sets in the past but never had this happen. Maybe it is something as basic as it needing a charge?

One thing I do know, is that even if I have to remove and test (even twice) every single component, then these boards SHALL be fixed!

[Crystaleyes]

Re: Electrolux ERG22 vacuum cleaner pcb fault

did you connect the charger?
some battery protection circuits latch off untill you try to charge the battery

It lives!!

I had charged the new battery pack and it still didn't work, so bearing in mind what you said, with the motor disconnected and the board on the bench with only the batteries, I just kept charging it until the charge led went off, then unplugging the charger for a few hours.

Somewhere around the fifth charging cycle, it finally started putting the battery voltage out to the motor terminals.

It is now fully reassembled and working fine. Have run it through a couple of charging cycles and even hoovered the house. The fucker is fixed! One down, one to go...


Cannot thank you enough for that essential little insight.

Nice one

[Crystaleyes]

Re: Electrolux ERG22 vacuum cleaner pcb fault

A final word and this thread is closed...

The second unit only needed one charge in order to come back to life.

As for the original, it is now returned to the owner, who asked what the problem had been?

Not wishing to 'let a good crisis go to waste' I told him that it was his good fortune that I am somewhat of an electronics repair genius, and that the problem had been a design fault on the part of the Electrolux engineers.
I told him that one of the trans-flux, variable wing dipacitors was at fault, and that after reprogramming the microprocessor code, that the problem was now resolved.

It seemed a better response than to tell him that I absolutely no feckin idea what was going on...

[sam_sam_sam]

Re: Electrolux ERG22 vacuum cleaner pcb fault

I like your reasoning about what to tell your customer it is kind-a funny as well

As for the original, it is now returned to the owner, who asked what the problem had been?

Not wishing to 'let a good crisis go to waste' I told him that it was his good fortune that I am somewhat of an electronics repair genius, and that the problem had been a design fault on the part of the Electrolux engineers.
I told him that one of the trans-flux, variable wing dipacitors was at fault, and that after reprogramming the microprocessor code, that the problem was now resolved.

It seemed a better response than to tell him that I absolutely no feckin idea what was going on...

[Crystaleyes]

Re: Electrolux ERG22 vacuum cleaner pcb fault

I like your reasoning about what to tell your customer it is kind-a funny as well

The best bit was giving the bullshit explanation in English - when he only speaks Portuguese...