ProTech 1230i Battery Chargers

[tridentwarrior]

I have a ProTech 1230i plus charger that suddenly died. Having over 40 years experience of working in electronics I took a look inside.

I have found the faults namely an open circuit primary winding on a transformer (T1) that caused a transistor (VT2) to short circuit, this in turn blew a resistor (R9) literally to pieces. However, I was able to recover and measure a piece of this, I calculated its total resistance to be about 47ohms.

I was able to substitute a resistor, an equivalant transistor and input a low subsitute voltage (6 volts ac) from another transformer. These test measures allowed the charger to boot and function, apparently correctly.

When I contacted the manufacturer in the USA for actual component details or a circuit diagram they were, shall I say "unhelpful" replying with the comment;

"this is proprietary information which I am not at liberty to release".

Can anyone help me ? What I need to know above all is the value in ohms of resistor R9. If the colour coded rings on the device may mean nothing to anyone looking at R9 no matter just tell me what they are in sequence, left to right or right to left or both and I will decode them.

It is likely that the ProTech models 1220i and 1240i use the same values components.

If anyone knows the secondary output voltage of T1 that would be great too.

If anyone out there could help with these answers that would be absolutely fanastic.

All the very best,

Trident Warrior

 

[amoya]

hi,
i know this post is a bit old but i came across it while looking for a schematic for these chargers im trying to repair 1240i, the resistor R9 in it is 150 ohms brown,not clear, brown. did you get any more info on these chargers.
thanks
dennis

 

[tridentwarrior]

hi,
i know this post is a bit old but i came across it while looking for a schematic for these chargers im trying to repair 1240i, the resistor R9 in it is 150 ohms brown,not clear, brown. did you get any more info on these chargers.
thanks
dennis

Hi Dennis,
thank you for your reply.

I got my hands on a working charger and you are right about the value of R9, the colour code is brown green brown for 150 ohms. I measured the secondary output from T1 as 9 volts, the primary voltage was around 115 volts. The working charger I aquired was an older version than the one I have now repaired. It has a few surface mounted devices on the underside of the main PCB and only three green indicator led's on the display. The later version has all the surface mounted devices, chips etc. and some additional ones on a sub PCB. The later one has several more led indicators for percentage of the total charge current being delivered, and the charging mode state.

I discovered on some of the newer version chargers there is a problem with the relevant display led,s, ciricuitry and charge voltages for sealed lead acid batteries and gel types being reversed. That could be a serious issue. There are also discrepancies relating to switch positions between the owners manual and the diagrams on the inside of the end caps. No surprise then that the manufacturers are reluctant to release technical information.

The charger I repaired was installed in a Legend yacht, apparently during its manufacture. When I explained what I had discovered, the owner decided to install a new charger from another manufacturer and sourced in the UK. I believe this was a very wise decision. I hope this is of some help to you.

Refurbished ProTech chargers are being offered on eBay in the USA at around $75.

Good luck with your repair, Peter

 

[amoya]

hi peter,
thanks for the reply im just out of curiosity trying to repair this charger it would have been nice if there had been a schematic available for this charger i may have to reverse engineer one, i have only got as far as finding the 186v dc that goes to the switching transistors 2sc3988 but there is no pwm signal on them so they do not produce any hv ac.
i will start going deeper to see what triggers the pwm chip. any more voltages from the circuit would be very useful.
thanks
dennis

 

[tridentwarrior]

hi peter,
thanks for the reply im just out of curiosity trying to repair this charger it would have been nice if there had been a schematic available for this charger i may have to reverse engineer one, i have only got as far as finding the 186v dc that goes to the switching transistors 2sc3988 but there is no pwm signal on them so they do not produce any hv ac.
i will start going deeper to see what triggers the pwm chip. any more voltages from the circuit would be very useful.
thanks
dennis

Hi Dennis,
there is an independant start up circuit that enegises T1, check for around 9v on the secondary, this feeds a bridge rectifier delivering around 12v DC to the drive circuitry of the 2SC3988's. If no output from T1 check for 115v on the primary, if no volts are present, there is probably a break down in the initial start up. If the 10uF 400v electrolytic capacitor's plastic skin is brown rather than black a good place to start would be to replace it. (I would replace it anyway,) it's close to the AC mains input end of the charger close to or on the edge of the board and may be mounted as a stand off component.

I replace any electrolytic capacitor that is has turned brown or has a slightly domed top as a matter of course. I changed 7 in total on the one I repaired.

Good luck!

 

[amoya]

hi peter,
it was the startup transformer with low voltage only getting 5volts out found R2 had gone high, i put in a low value and the charger came to life, do you know what the correct value is for R2, all the color bands have faded off im sure its just to limit inrush.
thanks for the help
dennis
Update found out the resistor is 47k

 

[tridentwarrior]

hi peter,
it was the startup transformer with low voltage only getting 5volts out found R2 had gone high, i put in a low value and the charger came to life, do you know what the correct value is for R2, all the color bands have faded off im sure its just to limit inrush.
thanks for the help
dennis
Update found out the resistor is 47k

Hi Dennis,
I will have to open the charger to identify the resistor value, I will do it in the near future rest assured. If you don't get a post reply in say 10 days, post again to remind me.
Cheers Peter

 

[amoya]

hi peter,
that resistor is 47k i got hold of another blown up unit and the resistors were good the real problem turned out to be burnt contacts on the relay, the unit is now running but after about an hour the relay starts to buzz and you can see the contacts arcing that must have been the original fault on the unit, still chasing to see what is causing it i see that they added 400v 10uf cap in that area so they had some problems.
interesting project learn a lot about these chargers now.
dennis