I have a TR7 that initially exhibited display issues¡ªrandom numbers appeared with dim brightness, and none of the bands were operational. After consulting with the forum and following the recommended steps, I inspected and cleaned all the unit¡¯s contacts, but unfortunately, there was no noticeable improvement.
Some time later, a friend and I resumed the repair process. After checking various components, we traced the issue to the DR7 board, specifically the U9022 counter (MC14518B). Upon replacing it, the display began to show the correct frequency. However, only three bands are currently working (1.5 ¨C 2.5 and 28.5 MHz).
We¡¯ve identified the root of the problem as the PROM memory (U9003) (MMI 6300), which has two inputs shorted.
I would greatly appreciate any information regarding this component, particularly the data it contains. Additionally, if this memory is no longer available on the market, does anyone know of a compatible replacement?
