I've got a 7603 that I received free with a 7D01 plug-in. It powers on (the power indicator lamp comes on), but the CRT does not show anything. Checking the voltages I find that the +130 V rail is way out of spec at +150 V. Checking the components in the +130 V regulator I find that Q852 is not recognized by my component tester, and the readings I get with the multimeter make it look like a resistor network (current flows both ways through all junctions).
The Tek part # is 151-0276-00, but the part has 2N5087 printed on it, so I'm guessing that's what it is. I don't have any 2N5087s in stock, but it looks like some other parts I have to hand might do the trick while I wait for 2N5087s to arrive (they are cheap and plentiful, but shipping seems a bit slow).
Here are the specs of the 2N5087 and the candidate parts:
2N5087: PNP, Vce = 50 V, Vcb = 50 V, Veb = 3 V, Pd = 625 mW, hFE = 250-800, fT = 40 MHz
2N2907A: PNP, Vce = 60 V, Vcb = 60 V, Veb = 5 V, Pd = 400 mW, hFE = 100-300, fT = 200 MHz
2N2904: PNP, Vce = 40 V, Vcb = 60 V, Veb = 5 V, Pd = 800 mW, hFE = 40-120, fT = 200 MHz
2N3906: PNP, Vce = 40 V, Vcb = 40 V, Veb = 5 V, Pd = 625 mW, hFE = 100-300, fT = 250 MHz
BC327-25: PNP, Vce 45 V, Vcb = 50 V, Veb = 5 V, Pd = 625 mW, hFE = 150-400, fT = 250 MHz
A1015: PNP, Vce = 50 V, Vcb = 50 V, Veb = 5 V, Pd = 400 mW, hFE = 70-400, fT = 80 MHz
I think that the salient spec in this circuit is Vce, and the 2N2907A and A1015 are the best fits , but their total power dissipation is low. The hFE specs are all lower than that of the 2N5087, but the Common Design Parts Catalog only indicates an hFE of 250 for the 151-0276, so several of these parts will probably satisfy that spec.
Any advice on what might work in place of the 2N5087 would be appreciated.
-- Jeff Dutky
