How to find a quartz crystal replacement for something without any info?

[keyboardguy]

Hey ya'll. I realize this is a watch repair forum, but I'm actually trying to repair an old Yamaha keyboard. This place seems super knowledgeable about quartz crystals, so I think I'm in the right place.

I'm a bit of a novice at electronics repair, but someone pointed out that likely the issue I'm having with my keyboard is a power regulation problem (it's very glitchy), particularly with the quartz crystal unit it uses. I would like to replace the crystal unit but I can't find any schematics or info on it. I'm wondering if it's possible I could somehow measure what kind of crystal unit it is (e.g., using an oscilloscope), how I would do this, and buy & solder a replacement?

Quarts crystal unit is identified as: 5.5M AD6496CA (VE760300)

EDIT: Photo of the quartz crystal unit is here https://imgur.com/a/5F4eWWj (see first photo, subsequent photos are of the back of the motherboard)

I've heard from others that 5.5M likely means 5 Mhz. Is this likely correct?

See my original post on reddit here: https://www.reddit.com/r/cheapkeys/comments/mum9bl/pss_480_rom_errors_and_glitches_help_me_fix_this/

Service manual of PSS 480 with board/circuit schematics: https://elektrotanya.com/yamaha_pss-480.pdf/download.html

I look forward to what you guys think.

Edited April 22, 2021 by keyboardguy

[jdm]

10 hours ago, keyboardguy said:

I realize this is a watch repair forum, but I'm actually trying to repair an old Yamaha keyboard. This place seems super knowledgeable about quartz crystals, so I think I'm in the right place.

We have few members that are knowleadable about electronics, maybe they can offer generic advice, however my suggestion is that you should not assume that the problem you have with "power regulation" is due to a crystal, and if you do not have at least a basic knowledge of electronics, as well the tools required,  should not attempt to repair or modify by yourself. A specialized forum would be a better venue of discussion for this. 

[HectorLooi]

I would agree with jdm. There should be other sound equipment forums that you could pose your question.

I'm not an electronics engineer but I have built many amplifiers and preamps. What do you mean by glitchy power supply? 

Did you try connecting the keyboard output to an external amplifier? Does it still sound glitchy?

How old is your keyboard? Many equipment from the '90s and early 2000s have problems with the electrolytic capacitors in the power supplies and ic decoupling caps. These normally result in AC hum and 'motorboating' sounds.

Quartz crystals rarely give any problems.

Probably if you do a web search of the model of your keyboard and problem that you are facing, you'll find answers in other forums.

Good luck and All the Best.

[JohnR725]

1 hour ago, HectorLooi said:

How old is your keyboard? Many equipment from the '90s and early 2000s have problems with the electrolytic capacitors in the power supplies and ic decoupling caps. These normally result in AC hum and 'motorboating' sounds.

Quartz crystals rarely give any problems.

Limited research I did indicates this is from the 80's. The problem with any electronics that is old electrolytic capacitors go bad with time. If you are having a power supply problem definitely look at the capacitors

Then I definitely agree quartz crystals usually don't go bad. Unfortunately the indication is there is no schematic for this that makes troubleshooting very difficult.

You'll notice in this link somebody tried to fix the errors and gave up. But it does indicate that there are capacitors that could be changed

http://boymeetssynth.blogspot.com/2018/10/yamaha-portsound-pss-480.html

 

 

[jdm]

4 hours ago, JohnR725 said:

The problem with any electronics that is old electrolytic capacitors go bad with time. 

No need for old age when the problem is with manufacturing 

https://en.wikipedia.org/wiki/Capacitor_plague

I have a video card which is exactly like that, all and any e.l. cap is bust at first sight. 

[JohnR725]

2 hours ago, jdm said:

No need for old age when the problem is with manufacturing 

Thanks for the heads up I didn't realize that Electrolytic capacitors lasted forever? Except you weren't paying attention I was already aware of the problem I already looked at Wikipedia this device is possibly made before that the indication was the 80s the Wikipedia claims 1999 and 2007.

The other reason I was well aware of this I'm pretty sure one of my motherboards failed because of this. Then all of electrolytic capacitors in the monitor that I'm staring at I replaced for this very problem.

But no matter what electrolytic capacitors have a life. That's why they're never used in mission-critical applications or anything that requires long life. If we look at the keyboard it was made before this particular problem you're talking about. For instance here's a link talks about the life of the capacitor. Except those also look like the kinda capacitors that would fail from the problem that you mentioned. But still he does talk about life of electrolytic capacitors

https://www.mathscinotes.com/2016/02/estimating-the-lifetime-of-an-electrolytic-capacitor/

Then

13 hours ago, keyboardguy said:

keyboard is a power regulation problem

If were talking about power supply problem then hopefully the original poster checked all of that? Same thing as and watch repair of the watch doesn't have enough power to run then it's a waste of time to do anything else.

Then the unfortunate problem with a device like this is relatively inexpensive and the reason there's no schematic is they don't expect you to troubleshoot at the component level. They expect you to replace the entire circuit board because it would've been cheaper.

 

 

 

[jdm]

1 hour ago, JohnR725 said:

Thanks for the heads up I didn't realize that Electrolytic capacitors lasted forever? Except you weren't paying attention I was already aware of the problem I already looked at Wikipedia this device is possibly made before that the indication was the 80s the Wikipedia claims 1999 and 2007.

Please don't think that I had overlooked your posting or underestimated your knowledge. I just posted about a documented case of accelerated component decay as opposed to the normal and expected one.

[JohnR725]

37 minutes ago, jdm said:

Please don't think that I had overlooked your posting or underestimated your knowledge.

then my bad, I apologize for possibly jumping to the wrong conclusion.

so now all in agreement that for a variety of reasons electrolytic capacitors have issues and in anything older especially in the power supply they should be definitely suspect of having issues.

the problem with any electronic device is how to tell if it's gone bad? Sometimes the top will be swollen. other times they leak and sometimes you'll see the fluid other times the fluid will dry up  just look like something was spilled near the capacitor.

then yes you can check the capacitance but you have to take it out. If you take it off the circuit board you might as well just replace it can be done with it.

 

[jdm]

12 minutes ago, JohnR725 said:

then yes you can check the capacitance but you have to take it out. If you take it off the circuit board you might as well just replace it can be done with it.

Ability to do in-circuit measurements is a great thing. I use an open source device, maybe not as good as professional tools but very useful anyway.

 

[HectorLooi]

Yes. I read about the bad electrolyte theory. Many equipment from that era failed because of bad capacitors. But newer equipment seem to have solved that problem.

The problem with newer equipment now is the use of lead free solder. Lead free solder leads to a lot of cold solder joints and a weird thing called "tin whiskers". These are microscopic strands of tin that seem to grow out from the solder. And when these whiskers touch another component or another whisker from a nearby joint, it causes a short circuit. I have personally seen pcbs with fuzzy stuff growing on some joints.

[keyboardguy]

Hey guys. Thanks for all your responses.

You are all correct in that I made an error and incorrectly thought the quartz crystal is related to power regulation. I'm actually still stuck on how to fix my PSS-480 keyboard. I know again this is a watch repair forum, but some of you seem extremely knowledgeable in electronics repair.

That said, I have made a few posts on reddit that have received a great deal of comments in the last 48 hours. if you are curious and think you could help me, I recommend checking them out to see where I'm at. I've also included high resolution photos of the entire board (front and back).

Here is my original post at reddit.com/r/cheapkeys:

https://www.reddit.com/r/cheapkeys/comments/mum9bl/pss_480_rom_errors_and_glitches_help_me_fix_this/

I describe the problems I was having with the unit and and indicated the issues I have now (powers on, no sound, buttons unresponsive). Sadly before I cleaned it with 99.5% IPA with an Oral-B toothbrush and using only the bristles, it had mostly functional sound, buttons were responsive, and it would often pass the self-test check (but it was random, which started my thread on reddit).

Currently, my post is now most active at reddit.com/r/AskElectronics

You can find all the latest info there (https://www.reddit.com/r/AskElectronics/comments/mvuv0s/how_to_measure_a_quartz_crystal_unit_and_find_a/) on where I'm at and links to the boards, including schematics, etc in my post (preview below).

Unfortunately I'm such a novice at fixing electronics that I can only hope (and pray) that someone will be able to identify the issue. I am learning as I go, but I am grateful for the journey. Thanks everyone!

Edited April 23, 2021 by keyboardguy

[JohnR725]

1 hour ago, keyboardguy said:

I describe the problems I was having with the unit and and indicated the issues I have now (powers on, no sound, buttons unresponsive). Sadly before I cleaned it with 99.5% IPA with an Oral-B toothbrush and using only the bristles, it had mostly functional sound, buttons were responsive, and it would often pass the self-test check (but it was random, which started my thread on reddit).

Looking through the other discussion here is something interesting

I design and repair audio electronics for a living, I'm not sure I've ever seen a bad crystal, but bad caps and poor solder joints in the power supply are pretty common.

Most failures are mechanical. It's bad switched and bad connectors.

You'll notice that this individual agrees bad crystals not exist for the most part poor solder joints do exist they had connectors and switches?

 

8 hours ago, HectorLooi said:

Yes. I read about the bad electrolyte theory. Many equipment from that era failed because of bad capacitors. But newer equipment seem to have solved that problem.

If you go back to the Wikipedia and read almost to the very bottom you'll see what the problem was poor industrial espionage. My understanding was when they stole the formula for the fluid found in the capacitors they didn't make it right. It's an amusing story where something at the very very beginning of the food chain ripples through the whole industry. Then of course the problem doesn't pop up instantaneously usually and takes a while the trace everything back then eventually they work it out and all the bad capacitors are hopefully? Okay there probably not gone there probably for sale on eBay somewhere but they should be gone.

8 hours ago, HectorLooi said:

The problem with newer equipment now is the use of lead free solder. Lead free solder leads to a lot of cold solder joints and a weird thing called "tin whiskers".

As usual the eagerness of people to eliminate evil and bad things often times they fail to grasp how much worse things are going to be with the fix.

Here's an interesting link explains tin Whiskers axiom around for a long time and strangely enough when it doesn't tell me is how long into the future will we have this problem. In other words once they grasp we had a problem did they figured out that they fix it or is it going to be a lingering problem.

https://nepp.nasa.gov/WHISKER/background/index.htm

 

Now back to the original problem? Another solution is to do something is very common that we do here if you're really desperate in need something look on eBay. Set up an active search it might take a while but maybe another one will show up.That looks like there's one in Canada

looking through the service manual is interesting. Looking at all the pictures you posted of the circuit boards on one of those discussions the capacitors visually looked fine. I noticed they nicely labeled the circuit board but they didn't show the power supply test points at least casually looking? But in one of the diagrams they do show the voltages. Like in watch repair started the basics are you getting power?

Troubling from your description it sounds like by attempting to clean and fix the contacts now the thing is working worse than before? If you look at the test procedure that Elgin around the testing keyboard switches or any of the switches until much later on so you do have to pass the basic ability or power up and get the unit functional. Which suggests you cleaning the keyboard shouldn't to fix the problem if you have a stuck  Switch for instance

one of the things you might try is removing the switch assembly I'm guessing it's a sheet of rubber perhaps? Removing all of that and try powering up the device you could leave the regular piano type keyboard switches in place. Even though they don't test the switches until later on it's possible of one or more of those are stuck down that might be the problem but it may be a long shot.

But I wouldn't do any of that until you verify that you have the correct voltages. Because without power the right power isn't going to work.