UBI EasyCoder 501 – Service Manual18626. TROUBLE SHOOTING, cont'd.26.1Printer “Dead”, cont'd.CPU Board failure• Ascertain if the trouble is actually due to a hardware deficiencyand not to the user program having got stuck in some way. Thisis easily done by running the print test program, see chapter 25.• The various parts of the memory could be checked using the UBIFingerprint instruction FUNCTEST$, see UBI Fingerprint Refer-ence Manual.• Check that no EPROM or SRAM packages are missing orincorrectly mounted.• In case of EPROMs or FLASH memory packages fitted on IC-104 and IC-105, check that straps are fitted correctly on P-100, P-101, and P-102, see chapter 17.3.• Check that UBI Fingerprint EPROMs IC-100 and IC-101 aremarked with IC-1 and IC-2 respectively and that both have thesame article number, see chapter 17.3.• Remove EPROMs IC-100 and IC-101 from their sockets and putthem back again (no pins outside the socket holes!).• Perform a checksum calculation by means of an EPROM pro-grammer and compare the result with the same EPROMs fromanother printer.• Check that the GAL circuit on IC-04 is fitted correctly and is ofthe correct type (article number 1-971805-xx).• Check that the GAL circuit on IC-700 is fitted correctly and is ofthe correct type:EasyCoder 501: article number 1-971803-xxEasyCoder 501 E: article number 1-971804-xxEasyCoder 501 SA: article number 1-971804-xx• Check that the ADS signal oscillator is running using ADS testpoint, see chapter 17.7.• Components mounted on sockets correctly orientated? Pins out ofsocket or obviously defective components?Examine both the soldering and component side of the CPUBoard for possible short-circuits or faulty soldering. Greyish orblackened lacquer is a symptom of overheating due to excessivecurrent.Continued!Packages that are smaller than theirsockets should always be fitted asillustrated. Check that the “Front” markis pointing in the direction indicated bythe white markings on the board.WARNING!If a RAM package is fitted upsidedown, the diode controlling the batteryrecharge could be damaged andrequire replacement.“Front” Mark
