Archive for July, 2017

hp 5334A Frequency Counter 100MHz

Sunday, July 23rd, 2017

Pick up this in junk yard for a low price and found inside all corrosive due to battery leakage!  After I do a cleaning and washing on the main PCB and replace all 6 pcs 100uF 15V cap with new Panasonic FC capacitors,  the set can work as it is.  Gone through performance check and all ok, self diagnostic also all OK, frequency can measure up to 105 MHz and level down to 35mVpp which is a bit better than spec.  Date code of part is mostly at year 1986, this this is a 30 years old hp equipment and is still working fine!  Made in USA.

 

Leader 1507A Repair (3-51FT-A Replacement)

Saturday, July 1st, 2017

This digital signal generator was stored for too long time and the internal battery was leaking and corroded the PCB near by.  After removing the battery (Nicad 3-51FT-A) and cleaning the PCB, power on test show that there was no display on the front panel.  One 1k resistors was also replaced in the charging circuit and put back a 3.7V 110mAh Ni-Polymer rechargeable battery, but the set still could not power on.  Note that the battery was got from ebay China seller with only SGD$0.9 and free shipping!  It is a 110mAh capacity and the original batter is 80mAh capacity.

After measuring the rail voltage, it was find that the two 5V supply after the regulator JRC 7805A was not at normal voltage, one close to zero and another one 4.5Vdc. Replacing the two regulators with Toshiba 7805S regulator and the set is back to normal.  Here are some photos for the repaired set.