Keyboard amp repair – Carlsbro Colt 45.

Keyboard amp repair Calrlsbro colt 45-1

This keyboard amp repair was for a Worksop based violinist who uses the full range speaker with his electric violin.

The amplifier was obtained second hand and had developed an intermittent problem in which the amp would drop out almost completely, leaving only a tinny high frequency signal. At first, I suspected that the LF driver or the crossover had become damaged, leaving only the HF driver active in the coaxial speaker. Normally, you would expect an HF driver to be damaged first, but LF drivers are still possible to damage.

However this wasn’t the problem. In the end I fixed the amp by replacing the corroded FX send jack and phones connectors. The shunt contacts on both of these interrupt the audio signal so they must be kept clean. To complete the Keyboard amp repair I then put the amp on soak test for 2 hours to verify that there were no further problems – there were none!

I shot a quick video part way through diagnosis:


If you need a keyboard amp repair, please drop me a message.

Carlsbro Repair – Cobra 80

Carlsbro Repair

Carlsbro Repair – Cobra 80

The owner of this Carlsbro repair complained of an intermittent crackling and occasional dropout. The fault was found to be within the power supply – a not uncommon source of trouble in bass amp repairs.

One of the pins on the bridge rectifier had developed a hairline crack through the pin. It was mounted to the rear panel, and when the panel flexed, the power connection arced, creating the described noises.

This repair was easily finished within the diagnostic period. When I find a quick fix for customer’s amps I always perform a routine ‘mini service’ to ensure the customer gets their money’s worth.

They’re not bad little amps these old Carlsbro Cobras – I gigged for many years in a jazz band using a Cobra 45!

If you have a Carlsbro Repair job that needs doing please, get in touch.