Hi guys,
I have been having some issues with my BK Precision 550 TTL tester. I bought it used on eBay and so far its performance has been mediocre at best. Of course, it may be the ICs that I trying to test.
However, while I am currently working on a Pinball Action repair (blind, as there are no schematics), my logic probe and data sheets have pointed out on a failed 74LS86. The BK Precision does not register this as a failed IC even though all the outputs are logic low or floating (inputs are good). For giggles, I tested the IC with my HP 10529A and the IC (in addition to other 2 74LS86 ICs) are all reported bad (and correctly so as their outputs are also floating when the inputs are good).
I am convinced that the ICs are bad as piggybacking with known good ones restores the output signals.
Does anyone have any explanation for this difference in behavior between the BK and HP? The reason I got the BK is for the 20 pin ICs…
Thanks,
Paris
I have been having some issues with my BK Precision 550 TTL tester. I bought it used on eBay and so far its performance has been mediocre at best. Of course, it may be the ICs that I trying to test.
However, while I am currently working on a Pinball Action repair (blind, as there are no schematics), my logic probe and data sheets have pointed out on a failed 74LS86. The BK Precision does not register this as a failed IC even though all the outputs are logic low or floating (inputs are good). For giggles, I tested the IC with my HP 10529A and the IC (in addition to other 2 74LS86 ICs) are all reported bad (and correctly so as their outputs are also floating when the inputs are good).
I am convinced that the ICs are bad as piggybacking with known good ones restores the output signals.
Does anyone have any explanation for this difference in behavior between the BK and HP? The reason I got the BK is for the 20 pin ICs…
Thanks,
Paris
