On 03/30/2018 03:39 AM, Hal Murray wrote:
t...@leapsecond.com said:
I updated http://leapsecond.com/museum/ulio/ with more manuals, and many
exterior / interior photos of the 301 module.
Thanks. My 301 says it is a 30TH Rev-A - mostly through hole parts. Same
layout.
Mine is the same. Circuit is very simple. The 20 pin IC is the U4226B
receiver chip and it has two external 60 kHz filter resonators. The 8
pin DIP is a TLV2770C op amp which seems to be a buffer to drive the S
meter from the very high impedance AGC test point on the receiver chip.
And I am guessing that the 2N3904 transistor is a buffer for the time
code output.
The modular cable connecting the receiver to the decoder is wired
straight through, not reversed as most telephone cables are. My fear is
that someone (like me) might at one point have used a reverse cable and
thus put reverse polarity on the board; I don't see any reverse power
protection.
Later today I'll tap into the four conductors on the cable and see what
signals I see on them, and also look for signs of life on the receiver chip.
BTW -- Donald Resor pointed me to UTSource which shows several Chinese
vendors as having them in stock. I get nervous about whether they are
the real thing or not, but will probably order a couple just in case.
The chip is a 20 pin TSSOP package, which isn't too hard to rework but
before putting hot air on the receiver board there are one or two
surrounding parts one would want to remove to avoid collateral damage.
John
_______________________________________________
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
