Service manual

H/Z-100 Service Bulletins
If "Device Controller Error" is presented or there is no prompt, check DS1 (HE 60-
621) for incorrect markings. A number of switches have been found to be
mismarked, or assembled with the cover upside down. A quick check is to check
continuity of each section. When DS1 is set as required, sections 0-3 and 6 should
be shorted when positioned toward the bottom of the board; all others open.
If the Z-207 controller will boot CP/M 85 and 86, but gives an I/O error for Z-DOS,
check U31 (74LS365A, HE 443-1039) for a defective gate; also DS1 (HE 60-621) for
switch "0" in the wrong position or open.
FSB-GEN-021: Winchester Notes
The following are general information notes that may help you solve problems and
understand the product better.
- When the winchester drive is replaced, it first has to be prepped. After prep is
completed there is a 50% ZDOS and a 50% CP/M partition set up on the disk.
Perform a CTRL-RESET on the machine, boot up on the winchester, and the
response will be a Hand Prompt on the screen with no message. This response
means 1) prep worked, 2) the disk can be written to, 3) the disk can be read.
Therefore the winchester drive is good.
- Under software control, the prep utility will keep track of the bad sectors. The
maximum allowable bad sector count is 168.
- If excessive soft errors are encountered on a system that works satisfactorily (it
preps, reads, writes, etc.), the problem usually will be alignment of the Data
Separator card. This card requires a scope with a 350 MHz bandwidth to perform the
alignment.
- Be careful when reconnecting the cables to the Winchester controller card. If the
leftmost ribbon connector is misconnected to the left, then a transistor located
directly to the right of the connector, Q101, will be blown. If this happens, it will not
be possible to initialize or write to the winchester drive and under ZDOS there will be
write error messages, and under Prep there will be a "Track Zero Has Bad Sectors"
message.
- If a problem develops in a system and gives parity or Bus error messages, and
dumps registers of the 8088 to the Bus; or if there is a total lock-up of the system
(dies for no apparent reason); either of these symptoms can be caused by a faulty
pair of PAL ICs, U28 and U29, in the lower left area of the controller card.
FSB-MON-002: ZVM-124 Monitor Servicing
The ZVM-124 is the same monitor as the ZVM-122/123 but is painted to match the
IBM colors. For service information, refer to the SM-ZVM-122/123 service manual.
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