Whatever is on the back panel, it has to be passive - the only connections appear to be the two 3.5mm connections exposed on the back plate, and (looking at the cable) a 2.5mm plug inside the case which then connects to the spare connector below the molex power connector.

Can you:
1) Extract the VU meter PCB from the case, and take a clear photo of both sides of the PCB
2) Confirm the markings shown on the integrated circuit U1. (no picture required for that bit - just read it and tell us what it says.
3) Trace where JP1 and JP2 cables go to

The VU meter board doesn't look complicated, and it might be possible to deduce a circuit diagram, and from that confirm/guess what the contents of the rear panel connector were.

(My only concern is that the "common" connection from a PC speaker outlet may not be at ground level - especially if the speaker amplifier is "bridged". In this situation connecting the common to the PC 0v line might stop audio output working)

mdog69 wrote:

Whatever is on the back panel, it has to be passive - the only connections appear to be the two 3.5mm connections exposed on the […]
Show full quote

Whatever is on the back panel, it has to be passive - the only connections appear to be the two 3.5mm connections exposed on the back plate, and (looking at the cable) a 2.5mm plug inside the case which then connects to the spare connector below the molex power connector.

Can you:
1) Extract the VU meter PCB from the case, and take a clear photo of both sides of the PCB
2) Confirm the markings shown on the integrated circuit U1. (no picture required for that bit - just read it and tell us what it says.
3) Trace where JP1 and JP2 cables go to

The VU meter board doesn't look complicated, and it might be possible to deduce a circuit diagram, and from that confirm/guess what the contents of the rear panel connector were.

(My only concern is that the "common" connection from a PC speaker outlet may not be at ground level - especially if the speaker amplifier is "bridged". In this situation connecting the common to the PC 0v line might stop audio output working)

1- Of course I can do
2- Same as above
3- JP1 goes to a front panel "volume dial" thing, JP2 goes to the VU meter itself and two LEDs that illuminates it.

Thnaks a lot for the expert answer, 😀 I'll return back with the requested info tonight.

Hope some of these help

installation guide - https://web.archive.org/web/20061207124031/ht … anual/final.pdf

datasheet - https://web.archive.org/web/20070415102631/ht … /cavalier24.pdf

VU-Meter Howto - https://web.archive.org/web/20050819154021/ht … CAVT02_1206.pdf

FAQ - https://web.archive.org/web/20070407205718if_ … duct_ID=CAV-T02

mdog69 wrote:

Whatever is on the back panel, it has to be passive - the only connections appear to be the two 3.5mm connections exposed on the […]
Show full quote

Whatever is on the back panel, it has to be passive - the only connections appear to be the two 3.5mm connections exposed on the back plate, and (looking at the cable) a 2.5mm plug inside the case which then connects to the spare connector below the molex power connector.

Can you:
1) Extract the VU meter PCB from the case, and take a clear photo of both sides of the PCB
2) Confirm the markings shown on the integrated circuit U1. (no picture required for that bit - just read it and tell us what it says.
3) Trace where JP1 and JP2 cables go to

The VU meter board doesn't look complicated, and it might be possible to deduce a circuit diagram, and from that confirm/guess what the contents of the rear panel connector were.

(My only concern is that the "common" connection from a PC speaker outlet may not be at ground level - especially if the speaker amplifier is "bridged". In this situation connecting the common to the PC 0v line might stop audio output working)

Here are the photos:

PC Hoarder Patrol wrote:

Hope some of these help […]
Show full quote

Hope some of these help

installation guide - https://web.archive.org/web/20061207124031/ht … anual/final.pdf

datasheet - https://web.archive.org/web/20070415102631/ht … /cavalier24.pdf

VU-Meter Howto - https://web.archive.org/web/20050819154021/ht … CAVT02_1206.pdf

FAQ - https://web.archive.org/web/20070407205718if_ … duct_ID=CAV-T02

Thnaks a lot for the documentation! 😀

OK the quick version:
Get a length of twin screened cable - cable that has two cores surrounded by an overall screen.

At the VU meter board end, wire it to a 0.1 molex connector.

Pin 1: Core #1
Pin 2: Screen
Pin 3: Core #2

The other end gets soldered to the speaker outputs on the back of your sound card.
Screen goes to 0v, the two other cores go to left and right.
Note that it doesn't matter which cable goes to left or to right - the two signals get added together on the VU meter board anyway.

From the documentation provided earlier in the post, the "volume control" is actually a sensitivity control for the VU meter.
If the needle hits maximum all the time, turn the sensitivity down.
If the needle doesn't move enough, turn the control up.
Once you've got it set right, you shouldn't need to change it.

The long bit:
I couldn't read the IC part number, so I put a bet on it being an LM324 quad op-amp.

For the record, the circuit does the following:
The signal comes in on pins 1 and 3, and each channel is AC coupled to the input of a separate inverting amplifier.
The outputs of the two amplifiers are then summed together, passed through the front panel "sensitivity" control and then into a third op-amp which drives the meter.
The whole thing runs off the +5v supply, which also feeds the VU meter LEDs via a resistor.

I think I can reasonably say:
The back panel module is just three sockets paralleled up, two facing outside, one facing inside.
The sensitivity control is probably a simple potentiometer, with the track connected to pins 1&3 and the wiper to pin 2.
The VU meter module probably contains just a meter, and an unknown number of LEDs with no dropper resistor (that's done by R112 on the PCB)

I've got a scruffy hand drawn circuit diagram that I'll scan and attach later for those who are interested.

/md69

Thnaks a lot for all the detailed information, and of course for your effort, I really appreciated it.

Soldering something on the sound card is a no for me, first of all I really suck at soldering and also I really don't want to fiddle with my only SB32 that way.

Instead, I will do something like this: I ordered the below parts:

I will solder a fan extension cable to the 3.5mm socket above (because of the 0.1 molex connector at its end), which will be assembled on to a small sheet of metal with a hole drilled on it:

Then I use the splitter above externally: OneI jack will go into the sound card speaker out, the other jack will go into the the newly created "input port", and socket end will be mating with my speaker jack.

Very much the same way actually that the document above describes. Is there any problems that you can see with it? (apart from the use of an unshielded cable)

Againi, thanks a lot for all the help! 🤣