DUAL CR 60 Repair

I bought this DUAL CR 60 vintage amplifier second-hand as "burnt", and it had a number of problems. As usual, the faults were associated with those created by novices and "the qualified", not experienced in repairing amplifiers. This meant sorting out the human-created problems first followed by naturally occurring faults. Consequently, it took longer to repair than I had anticipated, however it was all worth it in the end because it sounds wonderful. This amp provides a bass boost of +14 db and treble boost of +16 db, and depending upon the quality of your speakers the sound is very good.

I had the amplifier at full volume for half an hour and the new power resistors barely heated which just goes to show how little the zero crossover distortion is. This amplifier would have been a high-end product, and today, a wonderful example of German engineering.

One of the problems was associated with an open power resistor. These usually go open if the speaker terminals accidentally join or if the amplifier is over-loaded. Thankfully, the power transistors are very hardy and can take transient heavy loads.

I could not find 1-watt replacements, however these 5-watt resistors were cheaper and better quality.

The 5-watt resistors fit quite well.

Here is my extremely neat soldering.

There were also burnt circuit board traces that required repair.

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