The circuit is so simple and has so few parts, I'd be inclined to unsolder the transistors and diodes and test them. It should take less than a half hour with a Pace solder sucker or equivalent.
If there are bad transistors, you could likely bend the leads of a TO-220 part the fit the PCB and add a small heat sink. -John ============ > christopher hoover wrote: >> > The 2N1701 is a general purpose transistor rated at 60V, 2.5A. >> >> I've mentioned this before, but it bears repeating. >> >> If you are having trouble with an old school linear power supply, in >> many cases you can replace the TO-220 PNP pass transistor *and* the >> reguatlor circuit (based on a 723 or whatever) with a modern >> integrated regulator in TO-220 such as an LT1581. Strip the regular >> board of everything except for the the input and output caps (if they >> are still good) and wire up a pair of resistors to set the voltage. >> Add a couple of jumpers to complete the circuit. And then you are >> good to go. >> >> -ch >> > That probably wont work in this case. > The supply is actually an NPN discrete darlington buffered 32V zener > with a current limit transistor to set the battery charging current to > one of 2 values. > With the battery removed the supply output should rise to 32V - 2Vbe - a > diode drop, ie about 29.8V or so. > The series diode is required to isolate the battery from the regulator > output when the main fails. > It should be much quicker and easier to just find suitable transistors. > > Bruce > > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > > _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
