Relay flyback diode measurement is way off. Looks like Za is way off as well. What constitutes healthy Vbe for Qa?
It should also measure something big when the delay circuit+output relay are on and good. A figure like 10V-12V.
Possibly one of those. Or an error in one or more of the three LEDs. Wrong LED cathode orientation, or broken, something. But you say the LEDs light up.
Only to know if there's no signal output due to a broken input route. From IN to J1's Gate pin.
There could be a current path through a broken Qa but still without enough voltage drop to kick the relay.
Take action, test the diode the Zener and the transistor. If you have a component tester pull them out and test. There are also test ways with only a DMM you can Google up.
If this relay's coil is healthy it should measure around 1-1.5kΩ when not obstructed or paralleled by a conductive component.
In general I don't advise anybody to replace things blindly before testing the components so to learn debugging for the culprit. But you may as well do what you please. What if its a cold joint for instance? Better to be in the know.
Guess it's time to remove preamp board. Good excuse to get the extra goop off the heatsink. Since I would have to prove those pieces to test, I think I will just replace them.
The heatsink is not yet screwed to chassis, so by loosening the 6 wires from PS, removing screws to standoffs entire heatsink preamp board can be removed. I will reattach it temporarily with longer wires so I can work on it "out of chassis."
Here's the 3 LEDs. They light right up on fire up.
The heatsink is not yet screwed to chassis, so by loosening the 6 wires from PS, removing screws to standoffs entire heatsink preamp board can be removed. I will reattach it temporarily with longer wires so I can work on it "out of chassis."
Here's the 3 LEDs. They light right up on fire up.
Attachments
That makes good sense. It will be easier to work on with the extended wires from PS. Then I can work on it free from the confines of the chassis. To change something on board I can just flip it over. And, as you say the components can be tested. These were simple parts, usually I will kill the rarest, most closely matched items!
Russellc
That is exactly what is going on. LEDs light just before light bars on PS if I remember correctly.