This ChannelPlus DA-5500HHR has 15V dc coming in from an external supply and then it stops at some unidentifiable part. It's a surface mount, axial, glass looking, component about 5mm long. It is tubular and there is no writing on it. There is a blue stripe around it that might have changed color due to heat dissipation. Hooked up to my Simpson 464 DVM, it doesn't measure completely open but the numbers blink as though going to the next higher scale will put it in range, but it doesn't. On each end of the component, it has a round terminating pad which is what gets soldered to the PC board. The reference number on the board is Z1. No other components on the board has a reference mark that begins with a Z. From what I can trace from the PC board, the 15 volt supply goes through three paralleled 5 ohm resistors, which all measure ok, then it goes to this Z1 component and there is no output on the other end of it. From there, it goes to some type of three terminal semiconductor which is labeled 8HF2.
If I had to guess, I'd guess zener diode but that would seem to be an unusual place to put a zener diode.
Thanks for your reply.