故障现象：开机后热笔不热且单偏。检修及处理：该机的记录器由HG1101和HG1102厚膜电路组成，热笔由HG1101驱动。热笔单偏，查厚膜的外围电路无异常，判定HG1101内部损坏，由于该厚膜无法修复，换新后单偏的故障排除。该机热笔的加热电流是由IC（LF353）和Q2（A836）组成的电流 Symptoms: Hot pen is not hot and single bias after power on. Maintenance and processing: The recorder of this machine is composed of HG1101 and HG1102 thick film circuits. The hot pen is driven by HG1101. Hot pen single bias, check the thickness of the external circuit of the film without exception, determine the internal damage of HG1101, because the thick film can not be repaired, after the replacement of the single-bias troubleshooting. The heating current of the thermal pen is the current composed of IC (LF353) and Q2 (A836)