Epson LQ-2550 Product Support Bulletin(s) - Page 16

EPSON EPSON AMERICA, INC. SERVICE PRODUCT SUPPORT BULLETIN PSB NO.: P - 0 0 3 DA1TE: 10/04/88 PAGE: 1 of 1 SUBJECT: CENTRONICS PARALLEL REQUIREMENTS TO ELIMINATE RANDOM CHARACTERS USING THE LQ-2500 AND LQ-2550 The purpose of the bulletin is to resolve the problem of random characters generated by the LQ-2500 and the LQ-2550. We have received numerous reports from the field regarding this problem. After intensive testing, the problem was isolated to improper Centronics parallel cables. The types of problems encountered were: (1) Unsuitable shielding - some cable manufactures neglect to include the twisted pair grounds. The cables without proper shielding allow electronic fields to affect the data transfer, thus causing extraneous characters. Shielded cables encase the data lines to protect against external noise. (2) Unacceptable use of parallel communications - The recommended length of a parallel cable is 6 to 10 feet long. When a parallel cable is longer than 10 feet, the flow may become inconsistent causing random characters to be printed. For data transfer over 10 feet in length serial communications is recommended. If the two issues noted above are corrected, the majority of the problems regarding random characters should be eliminated. Proper shielding should always be verified before any other work is initiated. Many of the older inexpensive cables were manufactured without shielding to help keep production costs down. The length of a Centronic parallel cable should be kept to a maximum of 10 feet for optimum performance. For data transmission over 10 feet in length serial communications is recommended. EPSON AMERICA SERVICE, 23610 TEL0 AVENUE, TORRANCE, CALIF, 90505