Author Topic: GTECH SW08 not charging (Read 502 times)

BaldEagle · « **on:** March 19, 2021, 12:36:29 PM »

Well - can anyone out there help me?
I have a very old, and much loved, GTECH SW08 but I made a big mistake the other day and plugged in the wrong charger. Unfortunately it was the same jack but different polarity / voltage and now it no longer charges. I can still use it but I have to unscrew the bottom door, remove the battery and charge it externally.
A REAL PAIN!

I opened the case and removed the charging circuit - one of the resistors seems to have burnt out. GTECH do not seem able or willing to help me with this information. All I need is to know the value of the blown resistor (or resistors?). BUT - I cannot read the value of this resistor! Does anyone have a similar model and be willing to have alook inside?

The board is AN-101704BR and the resistor is labelled R3 (R2 may also be damaged). Can anyone tell me the value of those resistors or a link to a circuit diagram?

THANKS!

[Image code fixed by mod]

MVacs · « **Reply #1 on:** March 23, 2021, 02:53:09 PM »

I would expect Ryevac to be able to identify those by colour possibly. He is the board guru here. I'll link him

BaldEagle · « **Reply #2 on:** March 23, 2021, 03:02:03 PM »

THANKS

I could not make out the colours as they are slightly blackened.
Mind you my eyesight is not what it used to be.
Here are a few more photos (attached - I hope) to help Ryevac.

ryevac · « **Reply #3 on:** March 23, 2021, 09:20:52 PM »

Q1 will possibly be damaged also imo.
Sorry looking at the pics i cannot tell you the values due to the resistors burn out.
As you say best thing is for someone to open a good one up and take a pic

BaldEagle · « **Reply #4 on:** March 23, 2021, 11:09:46 PM »

Thanks for trying Ryevac and I will also try to get a new Q1 transistor.
It's a shame that Gtech do not seem to provide circuit diagrams.
In the meantime I will continue to charge the battery externally.

ryevac · « **Reply #5 on:** March 24, 2021, 09:21:26 PM »

Ok, i couldn't even find a pic of the pcb on google.

Not familiar with the board, the to220 device next to r7 is an lm317 adjustable regulator, and r7 1.5k is probably the regulators output setting bias /Vref resistor.
Careful with Q1, as i ain't really sure looking at the pic to what it actually does and there could be other issues.

BaldEagle · « **Reply #6 on:** March 25, 2021, 09:17:39 AM »

Hi again ryevac and thank you for those details.

NO - I searched all over GOOGLE but could not find any details of this circuit and Gtech were no help whatsoever.
They do not advise dismantling the machine to the extent I have ('cause 6V can be very dangerous?).
And that Gtech would not be responsible to any damage or injury caused by my tampering (neither would any court in the land?).

You would think they, at least, would have a circuit diagram and the resistor values but they would not provide that information.
There would also be less danger of damage or injury if they gave me the correct resistor values.
Or, indeed, just offered to sell me the entire board?
But hey if he can't repair it he will have to buy a new one increase our profits and add to the landfill problem.

If I ever find out what the burnt resistors (R2 R3) are I was going to replace them and see if charging works again.
Mind you I'm getting more and more used to just removing the battery and charging it.

PLAN B is to wire in 2 small bolts of the outside of the units so that I can attach the crocodile clips from my battery charger without turning the Gtech upside down, unscrewing the cover and removing the battery.
Note to self: Empty dust before turning sweeper upside down - AGAIN!

BaldEagle · « **Reply #7 on:** March 25, 2021, 01:53:34 PM »

Here is a better photo of the circuit board (both sides)

ryevac · « **Reply #8 on:** March 25, 2021, 09:10:16 PM »

Ah, whats the part number of Q1 please and the other black to92 device to its right in the picture.

BaldEagle · « **Reply #9 on:** March 25, 2021, 10:37:22 PM »

Q1 ST 8050D W8 LC
The other one 97TM052E TL431AC TI
Hope that helps.

ryevac · « **Reply #10 on:** March 29, 2021, 11:46:55 PM »

Ok, leave it with me - am a bit up to my eyes in it at the moment.

BaldEagle · « **Reply #11 on:** March 30, 2021, 12:11:05 AM »

No problem ryevac whenever you have the time, I'm really grateful for you help.
By the way I seem to have added an extra T to the second "transistor" it should have said 97M052E TL431AC not 97TM052E TL431AC