Well I see in the description of this part number the words "non latching" DPDT. Well I was wrong, but right about which positions are across the coil in the diagram. So that leads me to think 10 and 1 are where I measure? I dont see a "coil ohms" spec. This may not be the right part, but I think it is.
Any common silicone diode type will do. Its just for the relay coil's fly-back voltage suppression. When current in a coil is turned off, the magnetic field violently collapses and a high voltage fly-back peak can kill the coil's driving transistor.
Should be ok to test in this fashion. With the Ohm meter since its just a DC resistance value.
Relay is 1.027k ohms, so that's reading good. Diode behind relay, with red probe on banded end (which is the end lifted from board) and black on the other, nothing, no ohms. switching the probes to black on banded end, 5.0 M. Don't know what I should have measuring it? The zener 20.9 ohms both ways, one leg lifted. I dont know how this zener should measure either. Is the zener toast?
Measuring a replacement zener, like the diode, with red probe on banded end, nada. switching them, it read 27.46 0hms, but was slowly dropping, 27.46, 27.45, 27.44, and so on. Guess that zener was cooked? have plenty of replacements. Lets see if I have a replacement the diode behind relay just in case...
Russellc
Russellc
Removing other leg of zener. The only mishap this thing has seen was at first fireup, the one fuse blew. I had over tightened the mosfets and there was some continuity between heatsink and mosfet tab. Guessing that is when damage happened. appears zener is bad (I think, see post above) wish I could measure the BC550C but it was probably cooked too. If other numbers are OK, I can replace zener and BC550, reattach diode behind relay.
Then can again attempt fire up, adjust offset, power down and wait until it bleeds off dead of all voltage, add AD823 and fireup again, hopefully as it should this time. I will wait to find out if I am right with my assumptions. Out with the zener!
Then can again attempt fire up, adjust offset, power down and wait until it bleeds off dead of all voltage, add AD823 and fireup again, hopefully as it should this time. I will wait to find out if I am right with my assumptions. Out with the zener!
New zener and 547 installed, just waiting to see what you think about relay measurements (look spot on to me) and the diode behind relay. Dont know if that figure is right, but the no measurement one way, but measurement the other way seems good. I think I will reattach existing diode and attempt fire up. But seems like the voltage I had measured across diode wasnt correct...maybe it too is cooked.
Russellc
Russellc
Coil looks healthy. The diode should be good. There's a handy diode test mode on every DMM don't use the resistance mode. The Zener is in one way oriented a simple diode, in the other way its specific reverse voltage current gate. You can only test its one simple diode function with a DMM. This way you know it ain't completely broken. Replace with a new one to be sure it works to spec both ways. Most possibly it was about the relay driver transistor got blown during your Mosfets to sink shorting incident which took out that fuse too.
let me dig for a replacement, get other leg loose and see which of my meters does this and get it tested. I replaced the zener. It measured, well at least as I measured it, way different than a new replacement zener did.
I dont know if your video is for zener diodes as well, but if I measure it as in the video, one way is .013 V, and .014 V the other. Lets see how a replacement does.
I dont know if your video is for zener diodes as well, but if I measure it as in the video, one way is .013 V, and .014 V the other. Lets see how a replacement does.
Seeing some voltage both ways probed is fishy. The Zener was probably blown too.
That zener was cooked. A new one measured exactly as it should one way, nada the other. Looks like both the zener and the BC550 were taken out. Relay and diode working as they should. Power supply lights up, preamp dark for few seconds, then leds come on bright.