PG506/Repairs: Difference between revisions

PG506/Repairs (view source)

Revision as of 12:41, 6 May 2021

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Diagnosis of Failed Display section of PG506.

Mlynch

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-These are photos of the various wave forms taken at U400 and U470.
+If your PG506 Fails to show a display of the Variable Value on the display, check the wave forms at U400 and U470. In case of failure in the "STD. AMPLITUDE_Variable" mode, where the display and HIGH_LOW indicators do not operate; check for these wave forms at U470 and U400.  This assumes that the display momentarily shows "8.8" when the variable switch is pressed "in".  If the display does not show "8.8", then there are other issues related to the display and not the DVM circuit.
 U400= SN74LS00N  Link to datasheet here:  https://www.ti.com/lit/gpn/SN74LS00
 U470= TL710CP or equivalent
-In case of failure in the "STD. AMPLITUDE_Variable" mode, where the display and HIGH_LOW indicators do not operate; check for these wave forms at U470 and U400.  This assumes that the display momentarily shows "8.8" when the variable switch is pressed "in".  If the display does not show "8.8", then there are other issues related to the display and not the DVM circuit.
+Here is a link to photos of these wave forms.  There are two photos of a legal pad and hand notations which are an index key to associate the photos to the various pins.  Photos of U400 were taken at each pin and with the variable in Full CCW. ZERO and Full CW positions.  With few exceptions, there are 3 photos per pin.  Exceptions are Vcc, Ground and a few others.  Please refer to the proper PG506 Service Manual for more details.  These photos were taken on the RELAY Equipped Version of PG506 (Not "A")S/N is B040000 and above.
-Here is a link to photos of these wave forms.  There are two photos of a legal pad and hand notations which are an index key to associate the photos to the various pins.  Photos were taken at each pin and with the variable in Full CCW. ZERO and Full CW positions.  With few exceptions, there are 3 photos per pin.  Exceptions are Vcc, Ground and a few others.  Please refer to the proper PG506 Service Manual for more details.  These photos were taken on the RELAY Equipped Version of PG506 (Not "A")S/N is B040000 and above.
 PG 506 U400 AND U470 Wave forms   https://www.icloud.com/sharedalbum/#B0e532ODWGRrNkO