Changing the timer of an old battery charger to a longer time

[seanspotatobusiness]

I have a Uniross X-press 300 battery charger and it just like this but I think I have an older version with lower current:

The selector switch toggles between a six or nine hour charge time and since battery capacities have increased significantly since I bought it about 15 years ago, it needs to be switched off an on to reset the timer. Is there a way to modifiy the electronics inside to extend the timer, by modiying a resistor or capacitor for example? It looks like this inside:

 

[Harald Kapp]

Can you give us a close-up of the IC or simply note what's written on top of the IC?

 

[seanspotatobusiness]

Hi Harald, the chip is HCF4060BE WK01P0352. It's definitely got something to do with the timing.

There are a lot of versions of the chip but mine is pretty old, I think and no longer manufactured. I found a datasheet for HCF4060B without the E but it's very hard to understand the system of numbering the pins so it's hard to figure out which pins are in use.

 

[Harald Kapp]

The 4060B is a counter with integrated oscillator. The frequency of this chip is set by 2 resistors and a capacitor, see the datasheet, figure 12 unless an external oscillator is used (which is not obvious from your pictures).

The responsible capacitor seems to be this blue blob:

Check its connections, it should go to pin 9 of the 4060B and via a resistor to pin10. If so, place a second capacitor of the same capacity in parallel to double the time, or replace this cap by a cap of ~twice the capacity, same voltage rating.

 

[seanspotatobusiness]

Thanks, Harald; you're right! The capacitor does go to pin 9 and via a resistor to pin 10.