OK, I am convinced that it is correct as built.Hi Jim,
I think the orientation of the op-amps is correct. It looks like in both cases there is a 120k resistor connected to pin 2. Also on the etch side both have smd capacitors connected to pins 4 and 7
One of them is the wrong way round.Also haven't rechecked that the pinouts are actually correct (seen from below)
Done some back-tracing tonight using Inkscape. Unfortunately, layers are lost when exporting to png images - but you might get an idea how I intend to use Inkscape with layers (represented by different color/thickness), so it get pretty helpfull if nothing is known, but take some time (like when sitting home boring in winter evenings)
And I'm just hopelessing overdoing stuff like this (e.g. not need both channels etc. . .)
About monitoring voltage supply on opamps - well I may do another run for that tomorrow. Also haven't rechecked that the pinouts are actually correct (seen from below)
Yes - I'll happily explain that.I'm a bit puzzled as to what you're trying to do?, it'd be a LOT easier to draw the schematic out, and it would then be obvious what the pin connections are, and what opamps would fit.
Yes - I'll happily explain that.
Like told before (in other threads) - I've using this drawing software Inkscape for years now. But not so long ago, I figured out how to put the layer structure (just like any other kind of tre structure). So therefore I use this case not only to try to trouble shoot the device, but also to use Inkscape as efficient as possible.
A dead giveaway for dual opamps is that V+ is alway located on pin 8 and V- on pin 4.
For single opamps, V+ is located on pin 7 and V- on pin 4.
So if your red trace is V+ and the blue one is V-, then the board has a dual and a single opamp package per channel. As others have mentioned, very likely a TL072 and TL071, very popular devices in the audio world.
But since this is a RIAA preamp, most likely a NE5532 and a NE5534. They were considered lower noise, if I recall correctly.
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