soundcraft M4 power supply

[spiros]

Hi,

I have a burnt up resistor on the power supply board that is quite impossible to read and the ohm meter does not give any reading.
The device is a soundcraft M series, M4 mixer and the burnt resistor is R45 on the power supply pcb. Also the code name of the pcb is SC4105-06.
Anyone having a schematic indicating the value of this resistor? Or a same pcb/mixer and could maybe have a quick look would be appreciated.

Spiros

[vintagekiki]

Soundcraft schematic

https://music-electronics-forum.com/showthread.php?t=31550
Mozwell, thank you very much

https://music-electronics-forum.com/showthread.php?t=31550&p=320208&viewfull=1#post320208

https://music-electronics-forum.com/showthread.php?t=31550&p=320209&viewfull=1#post320209

https://music-electronics-forum.com/showthread.php?t=31550&p=320210&viewfull=1#post320210

https://music-electronics-forum.com/attachment.php?attachmentid=25499&d=1380858523
Soundcraft Spirit M4

https://elektrotanya.com/soundcraft_spirit-m4.zip/download.html
Soundcraft Spirit M4

https://elektrotanya.com/soundcraft_spirit-mseries_psu-digi-out.zip/download.html
Soundcraft Spirit-Mseries Psu-Digi-Out

https://www.manualslib.com/brand/soundcraft/power-supply.html
SoundCraft Power Supply manuals

https://www.badcaps.net/forum/showthread.php?t=59262
Soundcraft spirit m4 mixer troubleshooting

https://elektrotanya.com/soundcraft_spirit-mseries_psu-digi-out.zip/download.html
Soundcraft Spirit-Mseries Psu-Digi-Out

UnRar file Soundcraft Spirit-Mseries Psu-Digi-Out and find pdf files for SC4105 issue 1 switching PSU
Soundcraft_Spirit-Mseries_SW-PSU-Digi-out_pcb
Soundcraft_Spirit-Mseries_SW-PSU-Digi-out_sch (R45 is on page 3)

Reminder
Check if the resistor is really R45 and exactly where R45 is located
By schematics R45 has a value of 10k Ohm

[spiros]

thanks for your reply vintagekiki.
I looked all of your suggested links but couldn't locate a schematic for my board. I ve already found the M4 manual from electrotanya, but the power supply page does not seem to correspond to my power supply board. No R45 on it and several non existing component names referred.

[vintagekiki]

Resistor never burnt for no reason. Burnt is a consequence, the measurement is determined and eliminated by the cause.
It is usually a defect is some "big" consumer or a defective component in the filter chain.

According to the image of https://ibb.co/jP4Ok0 based on visible colors, it is most likely a resistor of 2W values of 100 (first cbrown) or 47 (first yellow) ohm (depending on which side the value is read)

In the lower right corner page 16 schematics there is a resistor R45 (behind IC1). See if there is a similar resistor or photo detail of the PCB where the R45 is located
If there is no effort, take a picture of the power supply on the side of the elements


Useful link

http://www.repairfaq.org/sam/smpsfaq.htm
Notes on the Troubleshooting and Repair of Small Switchmode Power Supplies