" wrote:


Long time since I've seen a post from you, Peter.


Odd Question. I am repairing a Sony mixer for a friend and it has a bad JRC 5023 op amp. It is dead-shorted - so I know it is bad. The rest of the board, diodes and transistors check OK.

As it happens, from a previous repair, I happen to have some jfet LF356 op amps in stock.

The operating voltages are within range. But the 5023 is a video/audio amp, the 356 seems to be 'more so'.
Given that there is some urgency on this and the mixer is quite obsolete (1980s vintage), waiting to get the parts from Mouser (Not in stock) or Newark, Digikey and so forth is easy enough but for the time constraint.

NOTE: I can troubleshoot discrete components and such easily enough. I boggle a bit at ICs, so thanks in advance for any suggestions.


Why would they use a video amp for audio? You are referencing a
RCA/Intersil/Harris/Intersil number which has nothing to do with a JRC
numbered part.

Does the schematic match the pinout of the FET Opamp? How is it
used? As an amp, or part of a filter? It should work in most circuits,
as long as the original part isn't a current amp.


Opamps are just blocks of gain. Their gain is set with resistors, so
the exact Opamp isn't critcal. The supply voltage, noise figure & DC
offset are. A 30 year old Opamp doesn't have much to brag about when it
comes to noise figure or offset. The only other problem is driving a
high capacitance load which can make it unstable.



I have used the LF373 dual version to replace older dual bipolar
Opamps with no real problems.