playmate Posted August 15, 2012 I have a 7898 power board with a bad ZD1 (zener diode) on it but don't have a schematic to find the right value to replace it. Does anybody have some technical data on this board or info on how to get a replacement board? I would rather fix it if possible but would get another one if need be....thanks. Share this post Link to post Share on other sites
Fugazi Posted August 15, 2012 Hi playmate, welcome to EB! I will move your topic to the Train Tech forum where it's more likely that you fill find expert help. Share this post Link to post Share on other sites
peterab Posted August 16, 2012 I don't have any specs for you but Briclink will help you find a replacement. I assume you mean This Part, if not the inventory should help. Share this post Link to post Share on other sites
playmate Posted August 16, 2012 Yes, that is the whole assembly in which the power board is in. Do you think anyone here would have the schematic for the board so I can fix the one I have that is not working? I'm a tech and have a variety of parts available but need to know what the value of ZD1 is because it is defective. Thanks for the help. Share this post Link to post Share on other sites
JopieK Posted August 16, 2012 Well, since you are a tech you could guess it couldn't you? Low drop, at least 9V I would suggest. Share this post Link to post Share on other sites
lightningtiger Posted August 16, 2012 Are you able to read the numbers on the diode body ? Plus are you also able to trace out the circuit from the pcb layout and from that you might be able to work out the voltage of the zener. Question is why did a zener fail ? Share this post Link to post Share on other sites
JopieK Posted August 16, 2012 He is a tech, so likely he applied some juice to it (read: more than he should have ;)). Share this post Link to post Share on other sites
1974 Posted August 16, 2012 (edited) Question is why did a zener fail ? It's an electronic component. Components fail Replace it with a 5V6 minimelf zenerdiode It's most likely a part of a reference voltage/Vreg for the potted mystery module/IR recievers as all the other components (LED + resistor, transistors and the 1930 H-bridge motor driver) will handle up to 11V I could trace it out but there's not much more to it than that, I reckon Edited August 16, 2012 by 1974 Share this post Link to post Share on other sites
playmate Posted August 16, 2012 Thanks for all the help- To answer some questions: Are you able to read the numbers on the diode body? No, it was damaged by battery corrosion. I could trace it out also but I thought I would ask here first for a schematic - nice sight for Lego enthusiast! JopieK said: "He is a tech, so likely he applied some juice to it (read: more than he should have ;))." JopieK is a real JoKer! Share this post Link to post Share on other sites
1974 Posted August 16, 2012 No, I didn't read the numbers on the component, I measured it. I 've been too long in this game to trust numbers on a component - measurement is what I trust It's five point six, trust me Just put it in the right way If you can't get a minimelf, it wouldn't be too hard to fit in a regular 0,6W leaded zenerdiode .. Share this post Link to post Share on other sites
JopieK Posted August 17, 2012 JopieK said: "He is a tech, so likely he applied some juice to it (read: more than he should have ;))." JopieK is a real JoKer! Well, since I used to teach tech students and still teach other students, I know myself and my kind a little ;) Lecturing keeps you remembering your own faults ;) Share this post Link to post Share on other sites
