Historical Measurement Equipment

Items

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  Hameg HM 1005 oscilloscope repair

  The vertical deflection driver for the CRT had been known bad for quite some time. Upon investigation a damaged trace was found (image 1) on one side of the totem pole drivers and it was bridged (image 2). After this the unit appeared fully functional if not for several intermittent potentiometers. After identifying several of these potentiometers including, brightness, focus and timebase further ailments where discovered. These include the misalignment of the delay and regular timebase. The timebases where promptly realigned by adjusting the belt (image 3). Finally, the front panel was cleaned (image 4 and 5). The final steps remain to clean or replace misbehaving potentiometers.

• Broken B input

  The B input of the PM3206 has stopped working from 50mv/div and above. Does not appear to be a loose connection. Needs further investigation

• Line filter replacement of Rifa capacitors.

  An attempt was made to replace the Rifa capacitors in the line filter used by a HP1653B. The outer casing was cut open using a dremel but revealed the inside is potted. No further attempt where made to remove the potting. Instead the filter was put together using conductive tape and put back inside the unit.

• Further reformation of electrolytic capacitors for the PM3410

  Further reformed electrolytic capacitors, this time for the two sub-assemblies of the PM3410. No real signs of large leakage although current consumption on several capacitors was quite high. This was to be expected as they are connected across the power supply lines so essentially the current consumption was just the standby current of the sub-assembly. The capacitors showed no signs of internal heating (tested using infrared thermometer).

• Reformed electrolytic capacitors

  All electrolytic capacitors on this part have been reformed by increasing the DC voltage up to either 58 volts or 2 volts below the maximum rating of the capacitor. None of the capacitors showed unusually large leakage or tended to lose charge quickly. It is deemed unnecessary to replace any of these capacitors. However, given the large maximum voltage of most capacitors a power up cycle using a variac is still deemed necessary.

• Complete cleaning of parts

  All parts have been cleaned using a rag shirt and progress can continue with electrical inspection

• Physically Inspection and partial cleaning

  Device is disassembled into half a dozen parts to investigate the internals. Several parts of the disassembly are cleaned using a rag shirt as to not scratch or damage to soft metals. Overall the device is decent conditions as there are no visible signs of corrosion. If any corrosion in is on the top surface of trimmer resistors as is quite common in this line of Philips devices. Most electrolytic capacitors have a rubber gasket at the bottom which shows visible signs of wear. It is unclear if this wear is due to leaking, this is something that must be thoroughly investigated before power up.