On 06/01/2021 20:16, pinnerite wrote:
Ten years ago I bult a low-noise pre-amp based on a 1970's article in Elektor magazine.

It used a TBA231 dual op-amp IC.

It didn't work but I did not have time to test all the copper runs etc before I wa over-whelmed with 'work'.

This week I took it out and started fault-finding.There was one open connection, poorly soldered. I then checked the power links throughout the board and they were fine.

Next i connected in a little waveform generator to the input and one of those timy LCD screened chinese oscilloscopes to the output. Nothing.

So with no shortcircuits, I concluded that the capacitors were OK whch only leaves the IC.

I do not have another TBA231 or equyivalent but have no idea how to test the chip.

I am a bit out of date with electronics since my heydays

So any suggestions will be welcome.

I suggest you measure all the voltages on each pin and come back here
for analysis.

For Info the datasheet:
http://www.bg-electronics.de/datenbl...ise/TBA231.pdf

Although the example test circuit doesn't include the use of Output Lag.
This circuit does:

https://www.vinylengine.com/turntabl...719d&mode=view