I made the quintessential newbie mistake: I removed 2 capacitors (CF07/CF08) without noting down the original lead position.

The interesting part is that the schematic (attached) seems to convey that one of them (CF07) should be a bipolar, but the actual capacitors put in place were both two polarized 100uF/10V. Usually I can relay on the schematic to tell me the polarity...but not in this case. Even for CF08, it's hard for me to dare to guess what should be the right direction.

How should I put the caps in place so that they don't explode in my face...? Is there an essential clue in the schematic, or an easy way to tell with a multimeter?

schematic enter image description here

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    \$\begingroup\$ CF108 looks to be marked on the schematic. You can trace the end to the conenctor and put the + lead on that end. Not sure about CF107. :( \$\endgroup\$ – Aaron May 20 at 18:58
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    \$\begingroup\$ Is pin4 on the connector "ground"? If so, then CF107 would go the same direction on the schematic. \$\endgroup\$ – Aaron May 20 at 19:00
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    \$\begingroup\$ CF08 is marked + towards teh connector. CF07 will be the same orientation. \$\endgroup\$ – Brian Drummond May 20 at 19:07

This looks like a completely passive circuit. There is no actual power to any of the components, just the audio signals coming in and going out. The only reason for the power on pins 6&8 is to power the LED.

You have two separate channels coming in on Pins 1 & 7 and going out on pins 3 & 5 (or maybe the opposite direction). CF07 and CF08 are just to block any DC difference between the input audio signal and output signal. This will depend on the rest of the circuit it is connected to.

I suggest you power up the circuit, and just use a voltmeter to read the DC voltage across CF07 and across CF08 . Install the caps to match any voltage you measure. If you don't see any voltage with the circuit powered you could wind the volume up and down and see if anything changes. If the voltage is always zero, then flip a coin :-).

Failing that, My best guess is that as pins 3 & 5 have a connection to Ground, they will tend to be at zero volts. The input on 1&7 is most likely to have a positive bias (if any), so I would suggest connecting the caps with CF07+ to pin 1 and CF08+ to pin 7.

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