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Tuesday, July 8, 2014

SPE Expert 1K-FA front panel keyboard replacement ... DONE !!

I have been using the SPE Expert 1K-FA HF/50 Mhz mosfet linear amplifier for quite a few years. It is a a very intelligent piece of equipment, technologically advanced, with great capabilities and superb performance.

As you may already know, I am a keen contester, and 1K-FA has taken part with me in many many contests, with no signs of tear or wear.

However, since past winter, a problem came up with it, some of its front panel keys stopped operating. Since those not working were the most vital ones (ON/OFF/POWER/DISPLAY/OPERATE), I decided to contact SPE for technical advice. I only did that lately, because I mostly remote control the amplifier and all its functions through its software.

SPE`s customer support team is really prepared to face and give solution to virtually any problem that may come up with their products.

The explanation I was given for the fault, was that a specific point of the flat cable membrane that goes from the front panel to the CPU board, is constantly in touch with the left metallic chassis of the amp, and that causes a few cable lines to break as temperature rises progressively. A broken line, of course, means loss of some keys control.

I ordered a new front panel keyboard replacement, with a very low cost indeed (!), which arrived a few days later. In the envelope, there was also a piece of velcro to put between the new flat cable membrane and the point where it comes in contact with the left metallic chassis.


After having removed top and bottom cabinets, I removed the front air filter to make the front panel extraction easier.

Front panel removed and unplugged from the main body of the amp. Although cabling connectors are very difficult to mix, it is better to take note (or a photo) of which cable of the main body goes to which connector of the front panel. It will save you from unneeded trouble !!
Also, note at the left part of the front panel, the flat cable membrane that connects the front panel keyboard with the CPU board ... that is the cause of the fault !!

 Several visible cracks amongst the cable lines of the membrane !! AHA !!

A better view of several of the cracked cable lines on the membrane.

The flat cable membrane end towards the CPU board ... looks like it needed a replacement, after all !!

Before accessing the keyboard, the CPU board has to be separated from the front panel. This is easily done by removing a few cables and four spacers.

Faulty keyboard removed from the front panel. Easily done with the help of a sharp knife, to cut through the powerful 3M glue used to stick the keyboard to the metallic chassis of the front panel. The LCD protective glass was cleaned with pure alcohol and a soft cloth to remove all remaining glue residues.

New keyboard placed on the front panel. Take great care in aligning both the four corners of the keyboard membrane, as well as the six small rectangular LED holes. Doing that right will help you later on when you will put the amp together again.

Here you may see the self-adhesive piece of Velcro, which I put between the keyboard flat cable membrane and the left side metallic chassis of the amp. From now on, chassis temperature will not affect this membrane.

Time for testing after repair ... Amp is back in business !!
100% success in this one.
I have to thank for their valuable help and technical notes Mr. Guido Pandolfi of SPE and Bob, W5UQ of Expert Amps USA.
Summary of repair:
Cost of keyboard: €10
Cost of shipping for keyboard: €6
Time of repair: 60 minutes, including unmounting and mounting the amp from/to the shack cabinets.
Result: All keyboard functions restored.

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