Waldorf Blofeld Dead Audio Repair

4 distance bolts and 3 screws must be removed. Also the wires of powerswitch must be desoldered to get the board out.
4 distance bolts and 3 screws must be removed. Also the wires of powerswitch must be desoldered to get the board out.

A little article about repairing a Woldorf Blofeld with the dead or low output problem. The description was already documented here , you can also try to find the pdf on the web with the filename “blofeld_low_output_repair.pdf”. I thought some german users would appreciate a german repair guide. Well this is just the english version of the german version :-) … maybe you appreciate this article nevertheless.

Symptom

Audio output and phones has very low or no output at all.

Diagnosis

As mentioned above, i am just repeating what is already known: problem is a blown resistor. It’s value is 6.8 Ohm and it can be found near the shift button.

Position of the broken resistor
Position of the broken resistor

What you need

Soldering station with a fine tip. LED-table light with built in Tischlampe mit eingebauter magnifier. Tweezer. I used leaded soldering wire.

Broken in two pieces, both sides still soldered on the board! No idea how this could happen.
Broken in two pieces, both sides still soldered on the board! No idea how this could happen.

Therapie

1. open the Blofeld


First reove the 4 screws on the bottm side. The lower half of the case can be removed.

2. desolder power switch


Yeah, rigth. The two wires from the power switch must be desoldered. If you don’t remove the powerswitch you won’t get the pcb out.

The new resistor, "6R8" means 6.8 Ohm. I ordered some more, maybe i get some mails of desparate german Blofeld users ...
The new resistor, “6R8” means 6.8 Ohm. I ordered some more, maybe i get some mails of desparate german Blofeld users …

3. remove pcb


Remove the 4 distance bolts and the 3 screws in the middle. The pcb can be pulled out of the case easier, if you dial the encoders flat side that they are facing away from the midi jacks.

4. find the broken part and desolder it


On my Blofeld the broken part was broken in the middle! Strange, very strange. I desoldered both halfs, cleaned the pads with some fresh solderwire and a desoldering braid.

The cleaned Pad with a size comparison of old style and SMD resistor. Technically a normal resistor should also do (pic shows 10kOhm though).
The cleaned Pad with a size comparison of old style and SMD resistor. Technically a normal resistor should also do (pic shows 10kOhm though).

5. Soldering the new part


This can come aout a bit tricky. The SMD part is just 3mm long, if are suddenly terrified by something (maybe a big black spider running over the pcb while you look through the magnifier) you might inhale or swallow your spare part. There might be more elegant ways, i did it like this: i put some solder on one pad to form a little hump. With one hand i held the part with the tweezer on this hump, with the other hand i put the iron on th patrs side lying on the hump. The solder under the part quickly gets fluid and the part id lying flat on the pcb. I soldered the other side and that was it. Dont hold the iron on the part for to long, it will easily be desoldered again.

The new part in it's place. Looks like the left side is not soldered propertly, but it is. The Blofeld works perfect now.
The new part in it’s place. Looks like the left side is not soldered propertly, but it is. The Blofeld works perfect now.

6. Putting it all back together
Point 3 to 1 in opposite direction. Don’t forget to resolder the powerswitch :)