PG506/Repairs

These are photos of the various wave forms taken at U400 and U470.

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 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

If you have questions contact me at >mlynch002@gmail.com< or >mlynch003@yahoo.com<.

PG506 Settings:

STD AMPLITUDE: SELECTED AMPLITUDE VARIABLE: OUT AMPLITUDE SWITCH: 1V

WAVE FORMS Photographed on TDS460A. See photos for scope settings as these can vary from photo to photo.