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Ok......how about this.... any one know if the wiring configuration is different for a 1968 convector vs. later ones? I looked up in my 69 radio book, and either the wiring on the connector has been swapped or the wiring is different for 68. The date on the unit is 6738 which makes it 38th week of 67......
Here's how to check the transistor with an ohm meter -> http://www.elexp.com/t_test.htm. Google will take you to dozens of similar links. The DS-501 is a 15 amp Germanium PNP type and the outside of the case is the collector. You can get the schematic equivalent layout by entering the part number here -> http://nte01.nteinc.com/nte/NTExRefSemiProd.nsf/$$Search
The chances of the transistor being bad are slim to none - it's rare. The fusible link resistor in the emitter line is there to prevent that.
The color code of the three wires to the convector changed occasionally. Blue became black. The green and yellow remained the same throughout. Green is base, yellow is emitter.
Not that many 7T1. The problems are usually elsewhere. But the 501's are routinely degraded for two reasons: Delco never applied thermal grease so heat does not flow to the sink. And, the almost short circuit aftermarket loading coil speakers (58-67), still being sold after all these years by the big vette parts suppliers, are cooking them.
Those speakers are, as you know, like flooring the gas pedal with the brakes firmly applied all the time. Oh well...
Thanks for the Info. Funny thing is, I found that same site after I had posted the original question, but still had a question about the wire configuration. The color scheme listed in the 69 Delco Radio service manual dose not seem to match what is wired on this unit that I have. Had sold the unit to someone and they returned as they stated it did not function. however, it passed the tests as listed on that link. So the concern I had was that the wiring config had been changed.