Help! cant find a Component in Uk.. a crystal!

[iainjh]

hi, help!

"indiana jones and the search for the NTSC Crystal for apple" or similar here.

my apple ii needs a new crystal, but I cannot for the life of me find a supplier in uk or in europe for the right part. Anyone who knows where to find this particular component, please could they help! Its NTSC hence needs to be the right freq. 14.31818 MHZ and has to be a series resonant part.

its a particular part apparently - some crystals work but the apple only then outputs monochrome. I have bought some off ebay and the apple works perfectly, the display is rock solid but dammit, no color, just B&W. I need the right type and part.

14.31818 MHZ
series resonant
2 pin/ through hole type

i quote from an apple ii site:

"
It is 14.31818 MHZ. However not all 14.31818 MHZ crystals are the same. You need a series resonant crystal. Even then, not all series resonant crystals will generate the correct frequency in an Apple II circuit. For an Apple II to generate correct color burst, the only part that I have found that consistently works is Vishay/Dale part number XT9UNLANA14M31818. This is available from Mouser (part number 73-XT49U1431-S)."

Mouser list the 73-XT49U1431-S as obselete and its out of stock. ebay wont turn it up and i may be searching element14 wrongly..

apparently CMAC HC49 part works, but I cant find that either.

please help!

cheers all, iain

[tbtorro]

Oh boy, have I not searched forever for this too, to convert my Europlus to color.. For the risk of discouraging you, I gave up in the end, sold my Eurplus and bought an NTSC IIe with the crystal (and color) included..

[roy_bates]

ill have a look in my parts box

EDIT: i have one you can have for postage i think,just send me a pm with your address and ill pop it in the mail when youve paid the postage bud

[iainjh]

Thank you! It's a very specific " series resonant" is that correct?

ill pm you in the am

thanks!!!

[eslapion]

How many would you guys want of these? They're like a dime a dozen around here...

[iainjh]

i think I'm now set! But thank you v much for the offer. I can buy loads of parts but finding those particular parts THAT WORK.. nightmare in pal-land

cheers!

mods the thread can close I think

[eslapion]

Please don't close.

I would like to try to find an equivalent which is not discontinued to help others.

The important factor when trying to find an equivalent in this particular case is the ESR or equivalent series resistance.

When searching on Digikey, I have found various crystals of 14.31818 MHz with ESR varying from 25 Ohms to 60 Ohms. Can you tell me the ESR of the original Vishay/Dale component?

ADDED EDIT:
the information on Mouser.com says the ESR of your original crystal is 25 Ohms.

Therefore this component available from Digikey should perform the job adequately (this is from ECS series HC-49UX):
http://www.digikey.ca/product-detail...1021-ND/827513

I have located other crystals of 14.31818 MHz on Mouser.com and they are also from Vishay but the ESR is 40 Ohms and that's probably why they don't work properly with your specific application.

ADDED EDIT 2:
This other component from a different manufacturer is also series resonant with an ESR of 25 Ohms (this is from CTS-Frequency controls series MP):
http://www.digikey.ca/product-detail...TX088-ND/67739

I hope having 2 gives more options.

[Bryce]

Although the ESR will decide whether it's suitable for Series oscillators, I doubt you'll find many Crystal datasheets that quote the ESR. Most parts will already tell you this in the part number. The datasheet will normally just list the load capacity value (Zero or S if series). Vishay for example use the following format:

Example: XT49U-16
A-RR-14M31

XT49U = Model Number (usually specifies the housing type)
16 = This is the coupling capacitor to be used. If this is missing or an S then they are usually series crystals.
A = Bulk packaging type.
RR = Further features such as working temperature range
14M31 = The frequency (May also be written in full ie: 14.31Mhz)

Bryce.

[eslapion]

... I doubt you'll find many Crystal datasheets that quote the ESR.

http://www.ecsxtal.com/store/pdf/hc49ux.pdf

http://www.ctscorp.com/wp-content/up...008-0308-0.pdf - page 3

'-)

[Bryce]

Ok, haven't noticed that before, but it's also not something that's really needed for most situations (including this one). In this case: http://www.ecsxtal.com/store/pdf/hc49ux.pdf all that you need to know is at the bottom of the page ie: Is there a load capacitance mentioned in the part number or is there an "S". Bringing ESR into it is complicating things more than you need to.

Bryce.