Some time ago I bought an Acom 1000. A good amplifier, reliable, quiet and wonderful protected.
I still had some problems in the beginning. When I turn on the amplifier it shuts sometimes off spontaneously.
Sometimes when heating up, sometimes after 5 or 10 minutes of operating. No errors appeared in the display. Acom advised me to replace C5. Thise capacitor often caused problems.
I also had to look critically at the voltage U1 (7805). Unfortunately without success.
Later on I noticed that this often occurred after I had moved the amp.
It was obvious something mechanical. After another chat with one of the Acom engineers it was more or less clear it had something to do
with the ROM (U12). Cleaning the pins and/or socket would solve the problem. Of course I did this and after that the amplifier worked flawlessly.
Before you start take note of the safety and ESD regulations described in the manual.
Remove the 9 black bolts which holds the cover in place and remove it.
Take the lids off from the tune-, load- and band knobs and set them in a certain position. Remember this position and remove the knobs. Do not rotate the knobs and
shafts in order to prevent twisting of the capacitor. Remove the 3 silver bolts to the underside of the amplifier.
These hold the front panel in place. This is easiest if the front of the amplifier is pushed something over the table edge. Then, push the amp back on the table.
Remove the 3 silver bolts on the top, tilt the front penal and lay it face down on the table. Remove the two most right-hand connectors and the 4 silver bolts
at the corners of the aluminum lid. Tilt the lid and take out the ROM to clean the pins and socket.
Place the ROM gently back into the socket and put the amp further together.
Be careful when replacing the capacitor knobs. If you rotate the shaft a bit the scale is no longer correct.
Then there is no other option than to remove the 15 bolts of the black inner cover to view the position of the caps.
Now the amp stood on the bench was the right opportunity to install an extra 24V fan. I used an extra switch because
the fan does make a bit too much noise. Now I can turn it on and off.
I recently received a notification from IZ1LAT, Claudio. He had more or less the same problem as you can see here, but cleaning the ROM only had limited results. Ultimately, after consultation with Val (Acom), he was able to find the solution and was happy to share his findings with us.
You will find his surprising contribution below.
Hi Rene,
As promised I'm here to update you on my amplifier problem.
Val has been very helpful these last few weeks and I have tried various solutions to fix the problem. I replaced the 7805 but to no avail. I powered both the microprocessor and the eprom directly, but also in this case the problem remained.
Then during various experiments I noticed that by disconnecting the display connector the amplifier would turn off. I looked into the circuit and saw that the microprocessor has no feedback on display operation, but everything is controlled via the serial link.
I discussed this with Val to see if there was a way to inhibit the processor's watchdog control of the display, but unfortunately it's not possible. Val sent me a test display to try, and with the new display the amp stays on without shutting down.
I tried the old display again and after 10 minutes the amp shut down. I plugged in the new display and the amp stays on!
Probably is a problem with the display processor causing the amplifier to shut down. I don't understand the usefulness of this feature, but it is. This could also explain the fact that shortly before switching off the data disappeared from the display.
However, the important thing is that the problem has finally been solved.
Thank you so much for your support.
