I have a '97 box and the disassembly is as you described for the '96 box, except I only have 9 screws on the bottom.
--- Bill Hawkins <[EMAIL PROTECTED]> wrote: > Received two of the subject units, one built in 96 > and one in 97. > The dates are the first two numbers in the serial > number. > > Took the 96 apart and learned that the LPRO-101 is > not physically > connected to the main board, except through a pin > connector. When > the unit is turned upside down, you can see a > pattern of 6 screws > in two rows of three. These secure the LPRO. The > rest of the screws > hold the main board. Do not turn the unit upside > down but stand it > on its rear fins as you remove the screws. This > keeps the LPRO from > dropping away and bending the pins. > > The LPRO has a thermal plate that provides good > conductivity to the > case, so it can dissipate about 15 watts. There is > no thermal goo > between the plate and the box, but the plate may be > stuck to the box. > Put a screw in a hole and push on it to release the > LPRO. Then, if > you have removed the 10 screws that hold the panel > to the box, it > should all lift out easily, with the LPRO hanging by > its connector. > I'd recommend laying the box down in its normal > position and sliding > the innards out horizontally. > > Imagine my surprise when what I'd learned didn't > work on the 97 box. > That assembly has a clamp that holds the LPRO in > place, so pushing on > a screw doesn't work. There are four screws on the > back, between the > fins. Loosen them to loosen the clamp, but don't > remove them. > > Reassembled both - you don't want to run the LPRO > without a heat sink. > The 97 unit drew 1.4 amps at 24 VDC at startup. The > NO GPS and Fault > lights were lit. The current dropped to .7 amp but > the Fault light was > still lit. Got 10 MHz at the J1 test point but > nothing at the 10 MHz > output. Went away for an hour, came back to find the > ON light, got 10 > MHz at J2, didn't check 15 MHz. The 96 unit had the > same behavior, but > the 10 MHz was more accurate. The box got quite > warm, but you could > keep your hand on it. (How's that for quantitative?) > > I have two Z3801s and two Racal-Dana model 1992 > counters set to Phase > A-B. > One counter has been measuring a 4040 cesium box > against one of the GPS > receivers. The other counter measures the phase > difference between the > Z3801s. With the 96 unit in place of the 4040, phase > rotation was 220 > degrees in 20 minutes. The GPS comparison doesn't > rotate, but varies > between 50 and 70 degrees. I consider that an > indication that the > receivers > are OK. The holdover accuracy varies between 0.5 and > 5 microseconds, > depending on when the crystal last cracked. > > If I did the math right, a 360 rotation will take > 2000 seconds. This > means > the LPRO is about 5x10E-11 off from GPS, no? > > Two other questions: > > What is the BITE pin on the LPRO? Some Built-In > Test? > > What is the protocol for the data at J6? Can it be > the same as the > Z3801? > > Bill Hawkins > > > _______________________________________________ > time-nuts mailing list > [email protected] > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > Fedora Core 4 Linux __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com _______________________________________________ time-nuts mailing list [email protected] https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
