anyone here into digital audio curcit design?

[Lost4words]

need to learn about crystal filters? and yes I am still drinking moosehead like a fish & I dont usually drink.....


But my question is not impared.

[hendo]

1. what do you need to know?

If I'm still around when you ask, I will answer.

[Lost4words]

13. thanks hindo I check back to see if you reply,

or you could PM me if my description of the problem rings any bells.

thank you

[Trajan]

2. Crystal Filters are analog circuits ....

X-tals are used for clocking 'digital' systems, and for sync and stuff like that, but their use is limited to clocks and frequency standards ....

So far ... There is no question to answer ....

EDIT: As described below ... It's been a while since I even thought about beat oscillators, tuned circuits, RF Mixers, IF Amplifiers and Superhetrodyne radio .... I have stayed mostly clear of RF most of my career ... But that is where 'X-tal filters' were used most ....

[geckosfeet]

6. You find quartz crsytals in all kinds of low cost consumer electronics.

Computers have several.

These are smallish $.50 tuning fork or wafer type devices. Very small. Very cheap. Mass produced low end timing devices.

Then again, high quality quartz crystals are also used in some of the most accurate atomic clocks in the world (or in orbit).

[Lost4words]

10. the ones in question have 3 leads, how do I test them? nt

[geckosfeet]

15. At a minimum, you will need a signal generator capable of the frequency the

crystals are rated at. You will also need an oscilloscope to monitor signal out from the crystal. A spectrum or network analyzer would be ideal but are rarely found in the home.

You will need to drive the device at a fairly low power level, slowly sweeping the frequency around the crystal frequency until you see a spike. The spike means that you have found the resonant frequency and that the crystal is oscillating. Now at least you know the leads and crystal aren't broken.

However, there are a number of electrical parameters for the crystal that may or may not be in spec if they are 20 years old. These are very difficult to measure even with specialized equipment.

http://en.wikipedia.org/wiki/Crystal_oscillator
http://www.ieee-uffc.org/frequency_control/links.asp

I used to make the damn things. Now I make websites.

on edit - or you build a little oscillator circuit and plug it in to see if the circuit works. But again - contact a crystal house (there are still a few around) and ask them if they have anything that they can replace it with. You may have to send it to them. Might cost you $25 -$50.

[Lost4words]

8. thaqnks thats more than I knew! been consumng, ignor misspellings.

:hi:

[MrsBrady]

3. crystal filter is old school

I use a lot of crystal oscillators in RF stuff. All of my audio gear is tubed. aaahhhhh sweet sweet analog!

[Lost4words]

7. My Main system Is McIntosh and its 38 years old, but thatsw another story.

yes I know even the Luxman reciever is at least 20 years old, I am old to.

[tkmorris]

4. Awesome. An electronics thread on DU

[Lost4words]

11. Yes but will I get the answer I need? the talent is out there for sure. nt

[Lost4words]

5. WOW Thanks all, here is my q

I am an old analog guy, valves and all. I am trying to repair a 20 year old Luxman reciever, I have the service manual and have noticed several CFs or crystal filters. I am familure with digital to a point, I suspect that the problem could be in this area. Please correct me if i am wrong and feel free to suggest.

Now I have replaced power transistors in many an older reciever so I am not a light weight. I prefer transformer output but I am aging myself.

Here is the symptom, under a steady load or input everything is fine but lets say my input is a CD player, during play everything is fine no distortion both channels working fine, once the CD is over and output drops I get a pop on the right channel. If lets say I play the CD on random cuts between each cut the right channel will do the same pop when the signal drops from the input and again when the signal returns for the next cut on the CD. I have checked with different input devices and its the same. With an LP or turntable there is no signal drop so no pop. Weird Huh? Also the unit has output relay protection and does not connect the speakers until the output to the speakers is checked and it seems to trigger overload very easly.

Output transistors check out ok,voltages are in spec no visable blown caps or resistors, and I have cleaned all contacts. Any suggestions on how to proceed would be greately apprecieated.

Also, I have replaced the reciever with the exact model I purchasede on EBay and everything is fine, same speakers, same periferals and no problem. So I would love to fix this unit and deploy it in another room.

What think Ye?

thats my issue, what do you think?

thanks
jim

[geckosfeet]

9. Unfortunately you need a fairly specialized and expensive piece of

equipment and fixturing to test the devices. Your best bet IMO is to find a local crystal house and see if you can solicit someone to check them out for you.

Are these surface mount or leaded devices?

[Lost4words]

12. leaded ....

the CF may not be the problem.

[Lost4words]

14. I dont think I will put out much cash as I have already replaced the unit for 50 bucks.

but if i COULD i WOULD LIKE TO FIX IT, (DARN) some people build model ships.

again I may be way off on my preliminary diagnoses.

[MannyGoldstein]

16. Have You Checked The Power Supply Voltage?

Is there a voltage glitch on the power supply when you hear the click?

In general, the best way to do is watch the glitch on the output with an oscilloscope (or a fast analog meter), then work backwards (input of power transistors, preamp, etc) until you find the origination.

Good luck!