Commercial Equipment Repairs
1. HP1741a Oscilloscope
I have had two of these instruments on my test bench, both with the same problem -
So far my own 1741A scope is working well.
a) One of the most common faults with these units that were mostly manufactured on the 1960s is solid carbon resistors that have aged high over the years. The only solution is to replace all that are out of specification with new carbon film parts of the same power ratings -
b) Electrolytic capacitors do dry out over long periods of time, particularly if located next to a valve as is the case in some of the receiver audio amplifier boards. If they do not reform correctly or show a significantly different value or high series resistance on a component tester then they should be replaced. See here for information on reforming capacitors.
c) The pressed pin sockets in some valveholders lose their tension after years of being heated and cooled and become intermittent. Best solution is to change the valveholder if a new one is available otherwise it is possible to tighten each socket by gently bending the edge in a little with a sharp scriber.
d) The plastic centre of the 0-
I use Revell Contacta Professional liquid glue for plastics for this purpose which pools easily and is commonly available from model shops in the UK and Europe. This glue may not be accepted for air-
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