My $22 ebay TDR 1502 showed up today. As expected, it won't power up. Unexpected: other than a small stress crack in one side of the case,
Methylene chloride will sort that out: it "melts" the plastic and has superb creep. But it is a carcinogen, so be careful.
it is in pristine condition and the original battery pack is in place. Even more surprising, the battery pack is in excellent physical condition.
I don't know a lot about NiCad batteries. The 1502 is designed to (a) require a battery pack in place and (b) for that pack to be putting out at least 9.95VDC to power up, even from the mains. The battery no load voltage reading is 6.1VDC.
That will prevent the 1502's charger charging the battery.
Do I have a snowball's chance in hell of getting these batteries to charge?
Not sure. You can stuff 0.1C current into them indefinitely, but I would start much lower. A current limited power supply is sufficient; say 15V/40mA.
EDIT: see
https://www.eevblog.com/forum/testgear/test-equipment-anonymous-(tea)-group-therapy-thread/msg2472483/#msg2472483Has any of my fellow TDR owners rebuilt one of these battery packs?
Yes.
![Smiley :)](https://www.eevblog.com/forum/Smileys/default/xsmiley.gif.pagespeed.ic.R8GFI-pF6f.png)
Get tagged cub-C NiCd cells, and solder short wires to the tags to join them together. Heatshrink is your friend.
I could put 12VDC into the TDR, as I did with the 1503, but I'd have to crack the case to do it, which I am not quite ready to do.
No, you don't have to crack the case. Use 4mm banana socket on wires from a bench PSU, and stuff them up the orifice left when you remove the battery pack. Make sure you get the polarity right. Set the bench PSU to 12V, and 250mA.
Whe you do decide to crack the case, realise that the ears will protect the front panel controls (cf Tek scopes), so position it vertically on its face and unscrew the four bolts on the rear. When unscrewed, you may need to twist a screwdriver to separate the case from the front panel.
When you replace the case, realise that pressing on the rear screws can spoil your day. The screws mate with bolts in the chassis that are peened into the chassis. Pressing the bolt can push the peened nut out of the chassis. So, unlike a normal scope, don't rest the case on the rear bolts, but do use the bolts to pull the case onto the chassis.
Once you've cracked the case, don't submerge it in 12" of water until you have followed all the instructions w.r.t. sealing the equipment. If you know where to look, there's 2kV right at your fingertips.
I am assuming, of course, that the charging circuit in the TDR is working...
It probably is, but you will go slowly mad trying to understand it. It woks
iff there is a functional battery (or simulation thereof).
Stuff 12V up the battery compartment, and look at the C6341/C6246 spewing acid over the PCB tracks, then go from there.