You should find pwer supply voltages of +/- 15 volts going to most of the op-amps.
You should find 48 volts for the phantom power source.
You should find 5 volts for the FX DSP or any other logic circuits.
You should find a +12 volt.
Here is a manual close to your unit (yours is an expansion of it):
http://elektrotanya.com/behringer_xenyx-1222fx_v1000_dpm5m_ub-spsu2_sch.zip/download.html
Testimonial: "Really great help ! Thanks once more !"
Hello Thanks for the infos.
It seems 5V is missing on the main board.
I'm unable to find where to click on the link you've posted to get the manual :-(
You click on the brownish dot left top with the arrow pointing down to download.
The file is compressed with 4 subfiles so save it in a new folder so you cana de-comppress it. The sub file with the SPUS2 label is the switching power supply. The 1222FX is the main board and FX.
The 5 volts on the main board... that is used primarily for the FX section... The little wires are tender and the problem might be right at a board attachment or connector.
It appears that the 5 volts enters the board at connection X34 which is probably a soldered in header to the board with the connector being at the power supply itself. 5 volts is on pins 8 and 9 and the return for the 5 volts is on pins 6 and 7. At the poower supply it appears that the 5 volts comes from X3 pin 5 and the return on X3 pin 6.
The 5 volts is regulated down from a 12 volt source via a 7805 regulator... Now this regulator is CURRENT and TEMP limited, so a short on the 5 volts on the main board will take the 5 volts to near zero. If you find say 100 mv of the 5 volts, then you go searching first with the finger test for very hot components, but never jumping to conclusion until verified component is actually bad... electrolytic caps are always suspect. IF you do see some voltage on the 5 volt buss, then the regulator is limiting the current so you go searching with millivoltmeter TOWARD places with LESS voltage... moving the return wire of your meter as needed... ideally you will find where the voltage is the lowest which is where you expect to find the short...
BE VERY CAUTIOUS around the fine-pitch surface mount IC's... you DO NOT want to short or damage them
Thanks a lot, fredy2 !
All voltages from PSU are correct.
I have contacted the previous tech and it turns out that the FX DSP module is missing ... (X83 connector)
I don't care with the FX effects, but the mixer level leds seem to depend of this board.
I would order a replacement board as there is too much to try to bypass. Behringer parts distributor is FullCompass.com, but you may need to get an official Behringer part number and incident number first... Beehriner is at 1-425-672-0816. FullCompass is really slow getting any parts...
Thanks once more for your help. Ordering the missing board is not possible. Thanks to the previous link you've posted, I found the 2442FX schematic. It worth asking : I'm looking for the components layouts, as printed references on board are mainly unreadable for passive ones... (PS: the FX board by-pass is on the good way :-) )
Hey fredy2 ! problem is solved Yeeeeepppppiiiiiiii !!!!!!!! Thanks to the your first link (this part is missing on the 2442FX schematic), I saw on FX board that grounds "A" and "D" are connected on FX board (through 0R), so I connected X83-1 to X83-6 and level meters are now OK. Resume : Main mix pot. was out-of-order, swapped it with one from a stereo input. FX board is missing : no level on meters. connected X83-1 to X83-6 to connected A and D grounds, all is now OK.
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Ooops ... sorry finally got it :-) this should be OK with it ! I'll keep you informed.
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