Crystal identification - Page 1
Forum section: electronics / beginners

author: fabricator4
author_rank: Newbie
timestamp: October 14, 2019, 02:42:01 am
content: Hi all, I finally managed to register. (Yahoo seemed to always eat the confirmation emails previously)I'm posting in beginners because, well I am. Although I've been tinkering for decades, I've had no formal training.Currently I'm trying to repair a device for work that is inoperable. It's supposed to get replaced but it's been broken for months now and has gone from very flaky when it gets warm to completely dead in the last few weeks. The company in question is extremely poor in terms of technical support and installation of these devices, even though they are integral to day to day operations. To make matters worse there's a heck of a lot these devices out there, so there's probably dozens of spare/broken units on someone's desk somewhere.The device in question is a keypad that is removable for remote operation, and also provides some rather important audible (beep) notifications.The usual flakiness would manifest itself as the keypad instantly disconnecting when removed from the holster. That sounds like the lithium ion battery inside is stuffed, you'd think. However it would sometimes play up when the ambient temperature was warm too. It would disconnect randomly, and sometimes the beeps would become broken squwarks. This will make a bit more sense as the story unfolds.Still thinking the problem was the battery I decided (against instructions and better judgement) to take the back off and check the battery. It turns out it was a rather standard lithium ion flat rolled package with three wires. I measured 4.something volts on red and black at the PCB so the problem is definitely NOT the battery. The battery was also not puffy... well maybe a tiny bit but nothing to suggest it was overdue for replacement.I started inspecting the board for corrosion or other obvious problems and I found one. An SMD crystal package popped off the board just from handling. Well, that's not normal. It has (or had) two pins. One stayed on the board and one stayed on the package. The solder where it broke was grey and crystalised. Now the problems all made sense, especially the squarking instead of beeping noises.I don't know if this is the only problem with the device but it's certainly the place to start. Trouble is, the SS package is not printed with just the frequency. It uses some HY-Q (brand on the package) code that is not terribly obvious.It's labelled 2H4M00000 with "HY-Q" directly under that. I checked on the HY-Q website and they talk about their 3CC (three column code) designations but this does not seem to conform to that - their 3CC table looks completely different and includes other information like temperatures and tolerance.On further investigation and looking at *other* companies markings I think this is a 4.0000 MHz crystal. I'd only be guessing as to what the "2H" is but it's probably temp/tolerance the same as their 3CC schema. I'm only guessing though, so I thought I'd run this by the forum before I slap my money down on a 4MHz crystal to do a repair that I'll never be able to tell anyone at work that I did.

author: RES
author_rank: Regular Contributor
timestamp: October 14, 2019, 09:01:57 am
content: 10M0000 is a 10MHz (10.0000M) xtal.http://casamodularsystems.com/index.php?main_page=product_info&cPath=64_146&products_id=2114

author: fabricator4
author_rank: Newbie
timestamp: October 14, 2019, 01:47:03 pm
content: Yes and thanks for the reply. I'm going to work on the assumption that the 'M' takes the place of the decimal in MHz and ignore the first part the code (2H).Interestingly, the "EB01S" code in your example does actually conform to the HY-Q 3CC code. It appears to mean -20 to +70C, +/- 50 ppm stability, +/- 50 ppm tolerance, and series resonant capacitance (whatever that means).I don't think my particular application is terribly critical so any 4MHz crystal of reasonable quality should be OK. If it works, no one will be the wiser (it started working "magically") and if it fails or there are other issues I may get a "please explain" in which case I'll do a Schultz "I know nuthink!". Of course they may actually provide a new keypad before I get the crystal, which would be the ideal outcome. I'm not holding my breath however...