[time-nuts] Tektronix TM500 Series Help
holrum at hotmail.com
Sun Jan 3 18:19:49 UTC 2010
The mainframe power transistors are NOT darlingtons. They are plain NPN/PNP power transistors with non-standard pinouts.
The non-high power slots are rated at least 15W (The PS503A power supply can drop the 33V DC lines to 0V at 0.4A). The high power slots use normal TO-3 transistors rated at least 50W.
If I remember correctly (but check first), regular pinout transistor pins are in the correct orientation if you flip them over... but then they are not properly heatsinked. I seem to remember an emergency repair to a TM515 done this way...
Depending upon the mainframe (some devices are connected to the motherboard via molex connectors), you may be able to just flip the cable connector or otherwise re-arrange the pins in the connector... leave a note saying what your did.
For devices soldered to the board, just use a regular transistor and connect the leads to the circuit board using short pieces of wire. Lead length is not a problem... the modules work on 3 foot long extender cables.
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