14.5 VDC @ 200 ma circuit needed for NiCad charger.

It's been my experience with these things that bad batteries blow up the wall warts for the chargers. This makes sense in light of what happened to your kludge replacement? You would think they would design better protected wall warts, but nope!

Rocky

The "wall warts" are designed to fail safely when there is a problem in the end use application (i.e. shorted cells in batteries). This is much preferable to starting a fire and is dictated in the U.L. 1310 standard that governs these direct plug in units. So many times the customer sees a dead charger and immediately assumes that the charger must be the culprit when in fact it's a problem in the load circuit itself. It's kind of like finding that a fuse has blown and assuming that the fuse is bad rather than correctly surmising that something has gone wrong in the circuit that the fuse is protecting. There are short circuit protected battery chargers available but like everything else they require more circuitry which translates into more $$$. This additonal cost will of course be passed directly on to the end user and in cases of consumer electronics that cost is unacceptable so what you end up with is a part that will do the job safely and fail safely when something is wrong in the load.

wlb

The number written on the wall wart bears some relationship to the nominal output voltage and some relationship to the maximum allowable current. These numbers may not be available simultaneously.

however the circuit inside the charger

Assuming don't make it so.

my old transformer was

How did you determine the 200mA number???? Don't confuse maximum ratings with actual current when the system is operating properly.

However mine is burned out and I can't tell what the color

Assuming...there's that word again...the numbers bear any relationship to the actual design and that all the charging current goes thru the resistor and, and, and, start with Ohm's law. (14.5-battery voltage)/0.2A. You do know which battery voltage to use don't you??? DO NOT STOP THERE. Use a meter to verify the actual current...assuming you know what actual current you want and modify the resistor to get the current you want with the battery voltage you want with the actual output from the wall wart.

I'll bet a nickel that at least one of the above assumptions is rubbish leading to an equivalent result.

Assuming...that word again...the cells are big in a drill and they're NiCd, which they usually...another interesting word often detrimental to successful implementation...are, they probably...I'll call this word dangerous...won't catch fire at 200mA...depending on the method of charge termination...a relevant concept that has yet to come up in discussion...but at least now, you have a way to get a number for the resistor.

If it were me, I'd use a light bulb...but If I mentioned that, I'd have to explain why, which I've done about a dozen times previously in this forum.

As always, when you don't know what you're doing and are ignoring advice from people who have experience exploding batteries, wear safety glasses. mike

Previous posts although inciteful do not answer the question at hand. The wall wart does say 14.5 VD @ 200ma, however the circuit inside the charger base is made for an AC wall wart. I'm assuming my old transformer was simply a 14.5V AC module. The DC rectification happens in the 4 diodes inside (full wave rectifier) the charging base. The 200 mA limitation is through R2. However mine is burned out and I can't tell what the color code is. Can someone tell me please, then I could verify if my batteries are bad, and which ones.