Posted on October 2, 2022 by Provo Electronics Case # 342553. Mcintosh 754 amplifier. Missing left channel. Case # 342553. Mcintosh 754 amplifier. Missing left channel. 09/27/2022 After troubleshooting found protection relay not working properly. Relay replacement solved the problem. Post navigationPrevious post: Repair case # 125432. Pioneer SA-9500II amplifier – no sound, keeps blowing main fuse.Next post: Case# 456234.Pioneer SX-950. Protection relay not clicking.