Need help identifying a zener diode - Page 1
Forum section: electronics / repair

author: tobor
author_rank: Contributor
timestamp: February 08, 2016, 03:48:29 am
content: So, I'm refurbishing my AR X-06 receiver, and on the main power supply board, there is a broken zener diode. The service manual references is as a UZ-20 (M, H) Zener Regulator. That's not enough information for my limited experience to figure out what the appropriate specs for a replacement would be.I'll attach the schematic for the board as well as a photo. It is component D903. D904 is an identical component, so, one solution that comes to mind, would be if I could determine through testing what the specs are on D904. However, if I do so, I need to be careful not to destroy it as well.Any help, on either a direct ID from the description, from it's use in the circuit, or on a method of determining the specs of the good component with little or no chance of damaging it, would be greatly appreciated!

author: Codex
author_rank: Contributor
timestamp: February 08, 2016, 05:05:27 am
content: Looks like they being used a voltage reference in "Transistor Zener Voltage Regulator" circuit. Although I can't read the labels on the schematic, so I don't know which Zener it is.If you know what voltage is suppose to be on the output power rail for that circuit, then maybe you can work out the right zener voltage.

author: Seekonk
author_rank: Super Contributor
timestamp: February 08, 2016, 08:21:04 am
content: Can't read schematic, but if they follow convention Q903 outputs 12V, so it would be about a 13V zener. Wouldn't be that critical.

author: circuitravi
author_rank: Contributor
timestamp: February 08, 2016, 08:54:34 am
content: I think it is a 20v zener diode. UZ-20 is a zener part number. Also i think it should be UZ-20BH or UZ-20BM. Please refer this datasheethttps://www.google.lk/url?sa=t&source=web&rct=j&url=http://files.rct.ru/pdf/diode/35.pdf&ved=0ahUKEwjbq5Dm5OfKAhUPBY4KHTUUDfAQFggjMAM&usg=AFQjCNHEmTyC9RGK8QGhzKyaMab2Pmv4SQIf you can please confirm voltage using other zener diode before replacing zener diode.Please confirm zener voltage before replacing zener diode. Otherwise your circuit get damage.Sent from my SM-N910C using Tapatalk

author: alsetalokin4017
author_rank: Super Contributor
timestamp: February 08, 2016, 10:44:18 am
content: I think so too, 20 volt zener.But you can remove the other one and test it like this:Be sure to read the Description of the video too.

author: alsetalokin4017
author_rank: Super Contributor
timestamp: February 08, 2016, 10:48:18 am
content: Quote from: Codex on February 08, 2016, 05:05:27 amsee attachment below:

author: EPTech
author_rank: Regular Contributor
timestamp: February 08, 2016, 11:00:11 am
content: Hi There,If both D903 and D904 are the same UZ-20 it is fairly easy. Just power the board and measure the voltage over the good zener diode and you will know the exact zener voltage. Just replace it by a good old BZX55Cxx (xx being 20 probably) and you are good to go.

author: tobor
author_rank: Contributor
timestamp: February 16, 2016, 04:23:29 am
content: Thank you all for your responses. Sorry, I've not been able to sit down and go through them all in detail yet...this working for a living sure cuts into my leisure time! I will go through them all, and watch that video on testing zeners.Now if I could just get a hold of a legible copy of the schematics for this this receiver...I've downloaded sever PDFs, but they all seem to be the same original scan, the resolution of which is too low for the schematic portion to be entirely readable. i checked with Acoustic Research, they directed me to the person they evidently unloaded all their receiver documentation to, but he doesn't have any for my model. I also went through the sticky topic on this forum, but only found another copy of the PDF I already have.If any one reading this knows of someone who might have an original service manual for an Acoustic Research X-06 stereo receiver, I would love to get in contact with them.Again, thank you all for your input, it's nice to have so much help available for the asking. Hopefully I'll be able to return the favor sometimeshttps://www.eevblog.com/forum/Smileys/default/grin.gif