View Full Version : Sears radial arm saw - digital readout problem

21st July 2014, 03:02 PM
My old saw is playing up.
Just fixed the carriage bearings.
Now the digital readout is not working properly.
The screen lights up and I can select the different modes. Eg rip elevation.
But the readout just stays on zero when the saw is moved.
I cannot find a common point except the circuit card.
Have changed battery and used a power supply to eliminate voltage as a problem.
The circuit card has a single chip. Marked with several numbers.
Which number is the likely part number to use to try and get another?
Or is there another possible single point fail?
I only have a small multimeter to probe around with.
So any help appreciated.

21st July 2014, 07:13 PM
Lyle, working on probabilities, it is unlikely that the electronics on the PCB would fail under normal operating conditions.

Normally most faults are caused by faulty power supplies, connectors, switches, wiring under flexing conditions, electrolytic capacitors, and often through unintended human intervention.
The actual ICs and transistors on the PCB normally fail due to spikes and transients from mains surges and storm lightning induced spikes, or due to other failing components.

Look firstly for intermittent connections from sensor leads and the like.
Look for a slightly dislodged connector somewhere, or a broken cable between connectors.
Check the internal connections on the main PCB, and the entry connections to the main display unit.
Look at the areas of the whole system which have been moved or recently worked on.
If it is possible to reset the system, do this.