FIX - Parkside Cordless Soldering Station 20V PLSA 20 Li B2

[SteveGB]

I bought a Parkside Cordless Soldering Station 20V PLSA 20 Li B2 as a spare to use away from home.

First experience was OK but slightly alarming, as the heat was up to seemingly bonkers levels, around 500 deg C, with all the flux burning off. On second use the tip disintegrated! I'd read the review and fix for the earlier A1 model, but didn't know that the B2 model was different.

AAAnywwwayyy! Read a load of stuff on the internet and one person seemed to identify the appropraite wires, but chose a resistor which still set the tip temp too high. Another suggested a higher value resistor. Here's my 'amalgum' of the two and notes about the changes it creates in use. Its pretty simple.

The unit will react differently (see later), but with a bit of common sense is usable and an improvement, operating at about 350 deg C.

In short, you need a 47 Ohm, 1/4 watt resistor, soldering iron and (seemingly) leaded solder, plus heat shrink and some thin protective sleeving made of woven glass fibre (which are present in the electronic 'personal fuming devices' so liberally scattered around our blessed land).

Here's what I did:

1. Disconnnect from the battery.
2. Take off the end the soldering iron by removing the large plastic nut
3. The nut enables the metal iron tip assembly to be removed by CAREFULLY sliding off.
4. Underneath is a very breakable ceramic heating element assembly - so be very careful with it!
5. Push the flex into the handle which will slide the ceramic tip and circuit connection board out of the handle fairly easily.
6. Identify the white ptc wire (white and black are PTC wires)
7. Desolder the white wire so it is free of the board
8. Cut the white wire a little shorter to accommodate the resistor length, so that when the resistor is soldered in series onto the wire end, the other end will go down the hole you originally removed the white wire from. Now older resistor to wire end.
9. Slip heat shrink (and shrink), then grp sleeve, over soldered connection
10. Re-solder resistor in place so it is now in series with the white wire ontothe connector pad.
11. Re-assemble in reverse order.

Things that seem to change:
a/ The unit will not switch itself off - I guess because the PTC detects (positive) changes in resistance as it heats, it expects these to drop to zero before turning off. Since you've put in extra resistance it will never drop to zero, so therefore won't automatically switch off. Common sense implication: leave to cool then disconnect from battery.

b/ By the same token, putting in extra resistance to achieve a lower (350 deg C 'ish) tip temperature will fool the PTC sensor into thinking its up to temperature earlier than it actually is when starting and the light goes green. Common sense implication: wait a bit and check when the solder melts!

Hope this is useful to others, I could have done with the info when I got the unit.

[David191921]

 ;)Hi, the guide guide is very useful, a tip burns for me too with each use due to the too high temperature.
I want to carry out this guide, but I don't understand how to solder the resistance.
Can you show me how and where did you weld it?
between black and white wire?
I see only white thread in the photo.
So it must be welded inside the handle of the welder? in this version b2.
can you send me a video? or step to perform to understand where to weld it, tutorial.
I would be grateful, please.

if I understand correctly, the white wire must be removed, cut and solder the resistance in the center of the wire, solder it again on the pcb of the handle?

[Haenk]

Before tinkering, return for a refund - why messing around with an unsafe device?

[SteveGB]

<<if I understand correctly, the white wire must be removed, cut and solder the resistance in the center of the wire, solder it again on the pcb of the handle?>>

Yes David, exactly as you understand.
Regards

[SteveGB]

Hi Haenk
Some people already have these and with the simple fix it provides a useful addition to one's toolkit. Which the near-500 degree C version didn't!

[David191921]

 do you know what resistance number I have to use to reach 350 degrees celcius max.
33 ohm ?working different resistance?

[SteveGB]

Hello, yes, as identified in my original post I used 47 Ohms. Achieves about 350 degrees C according to the thermocouple on my multimeter.

This was arrived at by reading other stuff posted and taking a judgement.

[David191921]

I soldered a 33ohm resistor.
I have no way to test the heat, which temperature can I reach with a 33ohm resistor?
with this resistance the light immediately turns green, but only after a few seconds does it begin to melt the tin.
maybe the temperature still too high with 33ohm?

[David191921]

do you recommend using a 47 ohm resistor?
So does the 33ohm maintain a higher temperature?

[Ian.M]

The PLSA 20 Li B1 will run from an old ~19V laptop PSU.  It draws quite a surge on startup from cold so I wouldn't expect any PSU under 80W to be happy.  I'm using a HP 18.5V 90W (4.9A) one.  Hook the PSU up to the battery terminals under the PLSA, which are the outer pair B+, B- (marked + and -).  It also needs a 10K resistor between the BS terminal (next to B-, externally unmarked) and B- to fake the presence of the thermistor in a battery pack that hasn't overheated!

If doing the mod inside the base, the easiest way of dealing with the label is to slit it neatly along the case seam between the button and the center of the sponge tray with an xacto knife.  You only need to remove the four screws in the left side of the main case, not the two in the side of the soldering iron holder.

The PCB is rather different from the A1 version BigClive tore down and reverse engineered: https://youtu.be/KPJJBa6-TVQ with the iron cable soldered direct to it, no footprint for a trimpot to adjust the temperature, and no separate regulator.  See attached PCB photos.

I cant find any info for the 'M43AN200' controller IC.  It runs direct from the nom. 20V battery supply (power in on pins 11 & 12 via 4R7 resistor) so presumably includes an internal regulator.  There are four test point pads in a line on the underside, that appear to connect to chip pins + Gnd, so it may still contain a reprogrammable (or OTP) MCU, or it could be an ASIC, and the pads simply test points.  Edit: One of Big Clive's commentators found the chip - On-Bright OB6606 is a MCS-51 core MCU optimised for brushed DC motor control applications with direct drive of a low side N-MOSFET, an ADC input optimised for low side current  sensing, and an on-chip 5V regulator.  Unfortunately the datasheet isn't publicly available.

N.B. the soldering iron sponge tray is very shallow and directly over the case seam which is over the main PCB, so *NEVER* wet the sponge in-situ! 

[mikerj]

Big Clive just released a video on modifying this unit:

[hibone]

My 2 cents.
I got the PLSA 20 LI B2 a couple weeks ago and I attempted the fix suggested by Big Clive, while also measuring the temperature with a multimeter based termocouple.
I put in a 44 ohm resistor and the temperature reached 380°C whereas Big Clive registered about 350°C. I also tried out a 120 ohm resistor, but the temperature increased to 380°C all the same, and moreover the led started blinking green and the soldering iron shutted down.
 

[Kurets]

The temperature sensor in the iron is an RTD at least. I tested it by heating it with another soldering iron and it behaves as expected. I modified mine with 33R extra and got 370C when the LED goes green.

Now I think that in practice it would be nicer to replace the whole circuit. I suspect that the brushless motor controller they are using is only "just" managing to control the temperature and any unexpected behaviours causes it to freak out.

i attempted adding 15R and for some reason this increased the temperature. Similarly, changing  the 499R surface mount resistors to different values also upsets the circuit.