Thanks for the reply! Yes, it is very hard. The board is from a radio shack scanner. I've never seen this before. If they did it on purpose
That makes sense.If it was from a scanner, it is probably to protect/hide any circuit that would allow changes to the scanning ranges, such as cell phone frequencies. In the
"old days", scanners could listen in on the analog cell bands. Then, governments passed laws forbidding this. Since many scanners were modifiable, this potting compound probably met the "legal requirement" of dis-allowing any modifications to the receiving frequencies, so cell bands could no longer be scanned. This way, older boards that were modifiable could still be used, but "locked" from modification with simple potting epoxy.