Harris Sigma DTV Transmitter fiber cables.

The Problem:

“The Harris Sigma IPA has shut down a few times with no faults on transmitter or in logs. The green lights go out for power and IPA, sometimes the IPA voltage light is finicky, though its on now.
If I goto standby and back. It resets to normal.
I replaced an IPA power supply recently. I am not sure that is related. As this happen once before causing me to replace power supply. I reduced power to 60% for now.”

I started thinking about this overnight as I remember the frustration I had with unknown fault problems on the Analog Harris sigma transmitter. Setting up a camera to watch the fault lights.  Days it dragged out, it may have been weeks.  But what was the solution?Then it dawned on me, I recalled the fix, PTL, the fibers optics! On the old transmitter I had to replace the fibers, the light became weak over time. Also it was related to power and heat, but only faintly related. Weak Light in the fiber! (or weak trip point on PCB).

On the the current problem I waited till it was muted into standby again, pulled and replaced fibers one at a time, and it came back on.

Now it could also be the fiber reciever, or transmitter, or a real drop out for a moment.  but in the old unit it was not.

I isolated the fiber to H13 Ion pump voltage, (the meter on pump shows a normal reading) that is the only fiber I must pull and insert to bring unit out of standby.

So if any green light fades for a moment it can cause the unit to goto standby, and stay there. The fibers are some of the green lights but not all.

looking for a green light out, or moment out, or monitor voltage at trip point. This happens at random is that is rather hard.

At this point, it looks like fiber (or related) or a moment drop out of signal.

Fibers in on A/D PCB Board
Fibers traveling through “the toaster or oven” cabinet (:






I shut down and reseated cables and fibers, though not cables on interface board in toaster box, its interesting to note that the two fibers I “suspect” are off the ion pump board that is open to the back air chamber and bend sideways ( I fixed that) and covered with light dust really that hole through cabinet should have been closed there, we shall see how it behaves after this. I replaced the blower air filter a fram tga3916 while in there it was a very tight fit so I left the shroud or cover off and out of unit on that filter, its not going anywhere.

Ion Pump and Low heat (filament) fibers
Ion Pump and Low heat (filament) fibers







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