Odd frequency crystal - Page 1
Forum section: electronics / repair

author: RyanG
author_rank: Regular Contributor
timestamp: April 20, 2018, 07:27:07 am
content: I have a few identical boards I am trying to work on, but the crystal oscillator is broken off of 2 of them. I have tried to find the same parts, but I can't seem to find any with the same frequency. They are 23.6428Mhz. The board does video output for some older black and white CRTs. I forgot to take a picture of the boards before I left work, but I believe the crystal is running into a 7404 hex inverter. Is there something that might be close enough in frequency or some other way to get this to work?

author: drussell
author_rank: Super Contributor
timestamp: April 20, 2018, 08:10:16 am
content: Bowling scoring display units, I presume? (AS-80/90 ??)If you can't scrounge good crystals from bad boards, really your only options are to call someone like Anderson Electronics that does custom frequency crystals and have some replacements made to order or make a new oscillator circuit / digital programmable oscillator somehow and wire that into the circuit as a replacement.(Well, that, or replace them with something like the Evolution upgrade boards that do HDMI output instead...)

author: RobK_NL
author_rank: Frequent Contributor
timestamp: April 20, 2018, 09:15:49 am
content: Quote from: RyanG on April 20, 2018, 07:27:07 amA programmable oscillator

author: ogden
author_rank: Super Contributor
timestamp: April 20, 2018, 09:22:28 am
content: Those Epson programmable oscillators are nice indeed, but is there any other way to avoid buying ~240$ SG-Writer programmator to let them run at desired frequency? Thou still could be cheaper than buying custom-cut crystals

author: RobK_NL
author_rank: Frequent Contributor
timestamp: April 20, 2018, 09:30:46 am
content: I specifically linked there, because you can have these programmed by DigiKey. Other vendors may also offer this service.

author: coromonadalix
author_rank: Super Contributor
timestamp: April 20, 2018, 10:31:12 am
content: maybe this crystal has an frequency divider at the outputyou may find another frequency to matchIs it for a system like this:http://www.evolutionscoring.com/files/EVOLTUION_AS-90_LOWER_MANUAL.pdf

author: Richard Crowley
author_rank: Super Contributor
timestamp: April 20, 2018, 10:48:53 am
content: Maxim DS1077 is an inexpensive programmable oscillator with a frequency range of 8.1kHz to 133MHz

author: RobK_NL
author_rank: Frequent Contributor
timestamp: April 20, 2018, 11:02:48 am
content: Quote from: Richard Crowley on April 20, 2018, 10:48:53 amBut with an initial tolerance of ±0.5% perhaps not the most suitable to replace a crystal.

author: ogden
author_rank: Super Contributor
timestamp: April 20, 2018, 11:06:31 am
content: Quote from: Richard Crowley on April 20, 2018, 10:48:53 amIt definitely cannot be used as crystal replacement:±0.5% variation over temp (+25°C to +70°C)±0.5% initial tolerance5000 ppmNote that crystals usually are 50ppm.

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: April 20, 2018, 11:27:17 am
content: does it need to be that accurate ? maybe try the closest you can find on the shelf

author: vk6zgo
author_rank: Super Contributor
timestamp: April 20, 2018, 12:05:25 pm
content: Quote from: mikeselectricstuff on April 20, 2018, 11:27:17 amI suppose it depends on how "fussy" it is.Years ago, we had a "dumb" terminal which used a 5.2MHz ( or thereabouts) crystal.We replaced it with a 5.5 MHz one, and everything worked normally.It looks like a discrete crystal, not an oscillator module, so maybe get a close one, & "pull" the frequency with parallel capacitance, series inductance, or a complex arrangement of L&C if necessary.

author: CJay
author_rank: Super Contributor
timestamp: April 20, 2018, 12:12:16 pm
content: There are plenty of programmamble MEMs oscillators that will replace that crystal (Silicon Labs hve/had a range of them that are pretty good), most of the 'better' distributors will program them for you for a small price, it'd probably be cheap enough to get a few for the price of one custom crystal.You might get away with a 24MHz crystal...It's an odd frequency though, it's not a multiple of the 'common' TV frequencies or the 'standard' frequencies I can think of off the top of my head, wonder what it's being used for, have you traced the output?

author: drussell
author_rank: Super Contributor
timestamp: April 20, 2018, 02:08:13 pm
content: Quote from: RobK_NL on April 20, 2018, 11:02:48 amQuote from: vk6zgo on April 20, 2018, 12:05:25 pmIt has to be pretty darn close. The Brunswick AS-80/90 systems' CPU boards operate at (or are divided from, I presume) one of two different frequencies depending on the model and version of either 23.64280 or 25.65504 Mhz and the display boards must match the CPU in use for them to work.Even those programmable oscillators like the Epson units mentioned above may not be suitable, from the datasheet, emphasis mine:Quote

author: drussell
author_rank: Super Contributor
timestamp: April 20, 2018, 02:29:23 pm
content: Quote from: CJay on April 20, 2018, 12:12:16 pmDoubtful... Even a 23.5920 probably won't work, though you might be able to modify the circuit to pull it up enough by loading it weirdly.QuoteIt's an internal scoring system, not some kind of broadcast thing so it doesn't have to be the same as "proper" TV standards, just enough that the TV will sync to it. Systems like that were often rather strange...Here is the installation manual for a series of modern replacements for that kind of systems' display boards that provide an HDMI output for a modern TV... Perhaps it will give you some insight into the kinds of units the OP is working on. Page 7-9 talks about the version for the AS-80/90 system that I believe the OP is working on.edit:http://www.evolutionscoring.com/files/EVOLUTION_MANUAL.pdf

author: CJay
author_rank: Super Contributor
timestamp: April 20, 2018, 02:49:32 pm
content: Well, if it has to be matched to the CPU board then why not change the crystal in both?Appreciate it makes them non compatible between different units but from what you're saying if there are two versions already then a third, if clearly marked, won't be too much of an issue?The SiLabs MEMS oscillators were pretty good, low jitter and good stability, good enough that I think in another thread here one was used to fix a Tek 'scope...If it *absolutely* has to be the right frequency and has to be a crystal there's alwayshttp://www.krystaly.cz/en/who can custom make to order and aren't expensive.I think your emphasis in the quote about 'video clock generation' is misplaced, it's a TTL Inverter clock signal, it's not going to be great quality and while the jitter may be an issue with high bit rate telecoms or standards compliant video for broadcast, I reckon it'd be fine for a bowling scoreboard, you said it yourself, " just enough that the TV will sync to it"They're cheap enough to try.

author: drussell
author_rank: Super Contributor
timestamp: April 20, 2018, 03:08:21 pm
content: Quote from: CJay on April 20, 2018, 02:49:32 pmYou would have to change not only the one on the CPU board but also every display board (both upper overhead and lower console) in the system. Depending on how many lanes the place has, or if these boards need to be able to be used at multiple locations, that could be problematic.QuoteIexpectthat any of those programmable oscillators would be good enough, it is just something to be aware of in case of potential problems.QuoteI agree completely. There are several good places to buy custom crystals and they aren't necessarily prohibitively expensive.QuoteIndeed!I honestly don't know enough about these things to know for sure. I've never had to work on one personally but helped someone with a similar type of system on another forum solve their problems several years ago. I don't even recall what system it was, but I ended up doing a fair bit of research and digging into some of their idiosyncrasies at the time...

author: drussell
author_rank: Super Contributor
timestamp: April 20, 2018, 03:36:14 pm
content: Actually, on closer inspection of these systems, it seems that each lane pair has a separate CPU board in the lower console (two lanes per CPU) rather than one master unit for a larger bank, so it might be possible to change the frequency slightly on all the "stuff" in one lane pair to another, slightly different frequency, at the expense of parts interchangeability.

author: edavid
author_rank: Super Contributor
timestamp: April 20, 2018, 03:56:37 pm
content: I also think that 24MHz crystals would be worth a try, but otherwise here are some cheap 23.69MHz crystals:http://halted.com/commerce/ccp12770-crystal-23-690-mhz-28hc-1829-1384.htmThat's only 0.2% off - hard to believe it wouldn't work.

author: RyanG
author_rank: Regular Contributor
timestamp: April 20, 2018, 05:13:09 pm
content: I am working on an AS90 scoring system as drussell has pointed out. To upgrade the entire system from this old stuff is about $250k to buy brand new stuff, so the boss isn't going to be doing that. Even the upgrade to the Evolution scoring, which still uses a lot of the old stuff is fairly expensive. I did think to try the 24Mhz crystals. I ordered them not long ago, and I am just waiting for them to come in. The problem with the system is that a lot of the stuff is obsolete. It was as if they had things made specifically for their system just to make it harder to work on for people like me. Brunswick has completely dropped support for the system now because it is from the early 90s. In general the system still works well. I got most of our CRT monitors to run great again thanks to james_s here on the forum. Each pair of lanes has 17 pcbs in them for the scoring system, and I have been trying to learn to repair each of them. I will bring one of the bad boards home and take some pictures if that would help get an idea if something could be easily done to modify the boards to work.

author: ogden
author_rank: Super Contributor
timestamp: April 20, 2018, 09:18:18 pm
content: Quote from: mikeselectricstuff on April 20, 2018, 11:27:17 amWould you rely on just trying? It easily could be so that when you try - it works, but just because it barely fits into one end of tolerance window. After few months situation can change and you can be screwed with your "I fixed it".

author: drussell
author_rank: Super Contributor
timestamp: April 20, 2018, 09:39:49 pm
content: Because all the boards on these systems use that weird clock frequency, I have a funny feeling it isn't going to work correctly, though without more thorough knowledge of the entire system or schematics or something, obviously I can't say for sure....I just have the impression that it is used to derive all sorts of things including whatever serial communications system these things use to talk between modules and to the front desk display terminal thingy that enables the lanes by game or time or whatever. I still think that you would probably have to change every crystal on all the boards in the entire system, and even that is only going to work if all the timings in the system are generated off these crystals and don't have to match anything else anywhere in the system.It's a good question, to be sure!

author: RyanG
author_rank: Regular Contributor
timestamp: April 20, 2018, 11:21:32 pm
content: I'm at work now, and I drew up the relevant part of the schematic because Brunswick does not provide them. They say the schematics are still under NDA. I didn't draw the other connections to the 7404 because I figure they have nothing to do with this circuit, as I assume this circuit just outputs to another pin of the 7404.

author: TheSteve
author_rank: Unknown
timestamp: April 21, 2018, 03:04:19 am
content: There used to be lots of places that would make a crystal to any frequency you wanted. Perhaps most are gone. I know I've had many custom crystals made. If you didn't know the exact characteristics of a crystal you wanted copied you would just send the original to them and they would measure and duplicate. It wasn't too expensive either, less then $20 bucks a crystal. There must still be one or two companies left who can do it.

author: drussell
author_rank: Super Contributor
timestamp: April 21, 2018, 09:00:15 pm
content: Quote from: TheSteve on April 21, 2018, 03:04:19 amI have also used custom crystals from a couple different places before with no issues.QuoteIndeed. There are still several in existence, perhaps some others here can share specific ones in their geographic area or specific experience WRT pricing, lead time, etc.Most of these kinds of places, if you contact them and say you need a general purpose, low cost, non-ultra-precision-spacecraft-grade crystal, can make you a few for a reasonable price, given the custom nature of the job, though it probably varies significantly between places depending on what their major market currently is so it probably pays to shop around.To start:Lap-Tech (Ontario, Canada)http://www.laptech.com(289)481-2019(also available from TFC in the UKwww.tfc.co.uk, they're part of Lap-Tech)Anderson Electronics (Pennsylvania, USA)http://www.aextal.com(814)695-4428FMI (California, USA)http://www.frequencymanagement.com(714)373-8100Transko (California, USA)https://www.transko.com/(714)528-8000FOX (Florida, USA)https://www.foxonline.com/EuroQuartz (UK)http://www.euroquartz.co.uk/+44(0)1460230000QuartzLab (UK)http://www.quartslab.com/Krystaly (Czech Republic)http://www.krystaly.cz/en/

author: drussell
author_rank: Super Contributor
timestamp: April 22, 2018, 12:34:46 am
content: Quote from: evb149 on April 22, 2018, 12:13:09 amThe OP stated that the crystals were physically missing.

author: RyanG
author_rank: Regular Contributor
timestamp: April 22, 2018, 06:11:11 am
content: Yes, they are missing. A lot of them were soldered standing straight up on the board, and people slid them on top of each other which ripped them off the board.