Hey Jerry! Great to hear from you. I probably won't become a regular again (it seems little has changed around here lol) but it's nice to hear from you and the others that have messaged me directly.
The 501s have different output devices, so you don't have to worry. On Semi is on their third version of the ThermalTrak BJTs now (they are aware that their early ones had design flaws) so people with later 601/452/7000/152/302/1201 etc. are probably fine too. I just hope my brother's 601s will be ok, even though serial numbers suggest otherwise.
Arthur
The 501s have different output devices, so you don't have to worry. On Semi is on their third version of the ThermalTrak BJTs now (they are aware that their early ones had design flaws) so people with later 601/452/7000/152/302/1201 etc. are probably fine too. I just hope my brother's 601s will be ok, even though serial numbers suggest otherwise.
Arthur