Send channel this failure may be caused by malnutrition. The fax machine has a Modem (modem) test function use this function to send channel. Its operation steps following: followed by by "FUNCTION" (function) "#", and "1", and "9", and "3", and "4" key entered TECH (technology) way, again by "FUNCTION", "6" key entered test way, by "YES" Select test project, select to "Modem TEST" (modem test) items Hou, by "YES" key select "FSK TEST" (frequency moved key controlled test), again by "YES" Enter FSK (frequency shift keying) signal test status.

Using oscilloscope measurements on the motherboard connector P2 17 pin waveform if the signal waveform normal, it means FSK signal and if not you should check and replace the signalling system and related components, ensure that the FSK signal is normal. Observation U14 ③, ④, Krispy Kreme is again foot waveforms; Krispy Kreme feet high, black-foot to send graphic signal input, third leg to send graphics output options. After looking up Krispy Kreme, black-foot signal was normal, while the third foot is no signal, then probably the U14 (TC4053BF) internal damage. After changing the U14 troubleshooting.