Burnt diodes

[adriangodwin]

It seems that after moderate use, the programmer PCB gets a bit browned near the AC power socket. This is due to the bridge rectifier diodes on the top (other) side of the board, which in my case have been getting hot enough to roughen the solder joints.

I guess they've survived for quite a few years and will likely survive a few more, but is this a universal problem ? Or is it just that some units run at a higher charge current ?

[Dataman (Neil Parker)]

Hello adriangodwin,

Thank you for your post. The bridge rectifier diodes getting toasty can be an indication of an issue with the battery pack. If the NiCad pack is ageing then it can take longer to charge causing heat build-up or if there is a shorted cell this can cause a problem too. The S4 charger limits the current to the programmer at around 650mAh, the S4 cannot limit the current itself. If a charger is used that supplies more than 650mAh then the diodes will get quite hot and possible fail.

Best regards,

Neil Parker
Dataman Programmers

[adriangodwin]

Thanks. I have a second hand device that came with no charger so it's possible it's been used with the wrong one. I noticed IanJ's unit also showed some overheating in this area.

The Nicads seem in surprisingly good condition, though - flat when I received it and I charged them externally as I didn't have the correct power supply, but they're holding the charge well.