Problems with Combo Amplifiers

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In a combo amplifier there is much more strain on the amp and preamp due to vibration as opposed to stack models and this may give you problems sooner or later because the speaker is in the same cabinet as the amplifer.

If this should happen, it is advisable to take it to an authorized repair service. But if you're a DIY type of person, you can try taking a look inside, and checking for cold solder joints. A cold solder joint is one that aparently looks good but if you move the component on the other side of the PCB while looking at the joint through a magnifying glass, you'll notice that the component lead moves in and out. These joints must be remelted or, if possible, remove the old solder and replace it with new solder. My advice would be to check the heavier components first like the electrolytic filter capacitors in the power supply section then move on according to component size.

Another problem you can run accross in these amps is a broken component lead. These are quite difficult to spot at first, even with a looking glass, and usually happen to components like output transistors or IC's which are mounted on a heatsink then directly soldered to the PCB.

The vibration of the speaker and the weight of the heatsink can cause the lead of the output device to break over time, but the crack is almost invisible. If your amp is making a garbling sound or there's a total malfunction at the output stage, this may well be the cause.