What was found
HF1 AND HF2 SHOWING INOP. GROUNDED - YES. PER B737-800 FIM 23-11 TASK 806. BOTH RTP SHOW INOP FOR HF1 AND HF2. BITE OF TRANSCEIVERS HF1 GREEN AND HF2 NO LIGHTS. RESET VHF 1,2,3 AND HF 1,2 CIRCUIT BREAKERS. NO HELP. REMOVED AND REPLACED HF2 TRANSCEIVER PER B737-800 AMM 23-11-21 LRU BITE TEST GOOD. BUT NO HELP. SWAPPED HF2 AND HF1 TRANSCEIVER. LRU TEST GOOD BUT NO HELP. SWAPPED HF2 AND HF1 BACK. FULLY POWERED DOWN AIRCRAFT. RESTORED POWER AND PERFORMED RTP - INOP DISPLAY TOGGLE FOR HF1 AND HF2 PER AMM 23-12-41. HF1 AND HF2 RETURNED. PERFORMED HF COMM SYS TEST IAW AMM 23-11-00 TEST GOOD.