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Acorn Computers Limited Winchester disk 110 Service Manual Download Page 2

WINCHESTER DISC
110 & 130

SERVICE MANUAL

Part No 0427,001
Issue 1
August 1984

Summary of Contents for Winchester disk 110

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Page 2: ...WINCHESTER DISC 110 130 SERVICE MANUAL Part No 0427 001 Issue 1 August 1984 ...

Page 3: ...est from Acorn Computers Technical Enquiries Acorn Computers welcome comments and suggestions relating to the product and this manual All correspondence should be addressed to Technical Enquiries Acorn Computers Limited Newmarket Road Cambridge CB5 8PD All maintenance and service on the product must be carried out by Acorn Computers authorised dealers Acorn Computers can accept no liability whatso...

Page 4: ...xpansion bus 14 5 2 1 Control address and data lines 14 5 2 2 Connector pinout 14 5 3 Winchester Disc Host Adapter 15 5 3 1 Address decoding and handshaking 15 5 3 2 Buffering 16 5 3 3 Termination 16 6 Test equipment and formatting 17 7 Fault finding 18 7 1 Power supply 18 7 2 Address decoding 19 7 2 1 FC40 read data 19 7 2 2 FC40 write data 19 7 2 3 FC41 read status 20 7 2 4 FC42 write select 20 ...

Page 5: ...tlet available is not suitable for the plug supplied the plug should be cut off and the appropriate plug fitted and wired as previously noted The moulded plug which was cut off must be disposed of as it would be a potential shock hazard if it were to be plugged in with the cut off end of mains cord exposed The moulded plug must be used with the fuse and the fuse carrier firmly in place The fuse ca...

Page 6: ...pter printed circuit board Faults detected in the disc drive disc controller board or power supply mean that the faulty part must either be returned for repair or replaced Dealers may hold stock of these items and should refer to information provided by their supplier for service procedures for these units The information contained in this manual is aimed at service engineers and Acorn dealers who...

Page 7: ...d at the rear of the unit A 3 15A type F fuse is located in a holder beneath the mains socket at the rear of the unit The Winchester Disc unit must be connected to the host microcomputer s 1MHz expansion bus socket using the ribbon cable provided There is a green activity lamp on the front panel which illuminates when the drive is being accessed The Winchester unit is fragile and must not be subje...

Page 8: ...it also contains a 240V AC fan for cooling 3 1 Disc drive Capacity 10M model 110 or 30M model 130 formatted Format ADAPTEC 33 sectors of 256 bytes Cylinders 306 10M version Heads 4 10M version Disc rpm 3600 3 2 ADAPTEC ACB 4000 Winchester disc controller Disc interface ST 412 Host interface SCSI 3 3 Host Adapter SCSI to 1 MHz expansion bus 3 4 Power supply Minimum input voltage 198V AC Maximum inp...

Page 9: ...ion lifetime 50 000 hours Mean time before failure 10 000 hours of typical usage 3 6 Outside dimensions height 100mm 108mm including feet width 335mm depth 365mm 3 7 Connections Two 37 way D type socket connectors are provided for 1MHz bus daisy chain connection These are on the rear panel and are labelled 1MHz bus IN and OUT although they are in fact identical Three removable resistor packs are m...

Page 10: ...ceable i Ensure that the unit is disconnected from the mains power supply before dismantling it ii To service the Host Adapter PCB remove the three small phillips screws labelled A in figure 1 underneath the front of the unit which hold on the front panel The unit may be turned on its back to do this if desired but then remember that references to left and right in the following description will b...

Page 11: ...s turned on its back to gain access to the screws on the bottom panel now turn it back the right way up v Remove the single small phillips screw labelled C in figure 1 from the rear panel middle top near the ribbon cable vi Slide the top cover forward and off being careful not to get any of the cables or components caught in it The lug which was located by the screw in the rear panel will usually ...

Page 12: ... on its four plastic pillars The Host Adapter PCB is the lower board and may be worked upon without removal If it is necessary to replace the Host Adapter PCB then it can be removed in the same way as the top board ix No further disassembly must be carried out The cover of the hard disc drive unit must NOT be removed Reverse the above procedure to reassemble the unit Do not forget to reconnect the...

Page 13: ...board and the 1MHz expansion bus to allow a full understanding of the operation of the Host Adapter board For the full specification of the SCSI interface see the relevant literature 5 1 The disc controller board The disc controller used in the Winchester Disc unit is a device which will send or accept parallel byte data to or from the host microcomputer via 1MHz bus and Host Adapter and will read...

Page 14: ...t to indicate input to the initiator disc to computer and is deasserted to indicate output to the target computer to disc REQUEST REQ pin 48 is asserted by the target to indicate a request for a REQ ACK data transfer handshake ACKNOWLEDGE ACK pin 38 is asserted by the initiator to indicate acknowledgement of a REQ ACK data transfer handshake The REQ ACK handshake provides the asynchronous timing o...

Page 15: ... of these phases at any given time Bus phases occur in a prescribed sequence The reset condition can interrupt any phase and is always followed by bus free Any other phase can also be followed by the bus free phase The prescribed sequence is from bus free to selection to one or more of the information transfer phases to bus free again There are no restrictions on the order of information transfer ...

Page 16: ...r 1 0 1 command phase initiator to target 1 0 0 status phase target to initiator 0 0 1 message out phase initiator to target not used 0 0 0 message in phase target to initiator All signals active low 0 assertion 1 deassertion Table 1 Information transfer phases The information transfer phases use the REQ ACK handshake to control information transfer each REQ ACK allows the transfer of 1 byte The h...

Page 17: ...sferred from target to initiator The target asserts I O and deasserts MSG and C D Message out phase not used by the system available for future expansion Message in phase allows the target to send a message byte to notify completion of a command 5 1 4 The reset condition The reset condition is caused by the assertion of RST and immediately clears the bus and resets the system Regardless of the pri...

Page 18: ...PLETE 0V 9 10 TRACK 0 0V 11 12 WRITE FAULT 0V 13 14 HEAD SELECT 2 0 0V 15 16 RESERVED 0V 17 18 HEAD SELECT 2 1 0V 19 20 INDEX 0V 21 22 READY 0V 23 24 STEP 0V 25 26 DRIVE SELECT 1 0V 27 28 DRIVE SELECT 2 0V 29 30 DRIVE SELECT 3 0V 31 32 DRIVE SELECT 4 0V 33 34 DIRECTION IN J0 Pin no DRIVE SELECTED 1 2 0V RESERVED 3 4 0V RESERVED 5 6 0V RESERVED 7 8 0V RESERVED 9 10 RESERVED 0V 11 12 0V MFM WRITE DA...

Page 19: ...ow NRST not reset pin 14 is output only active low system reset line It is active on power up and when the BREAK key is pressed NPGFC not page FC pin 10 is a signal decoded from the top 8 system address lines A8 to A15 NPGFC is an active low signal which is low when the address high byte is FC ie when the full address is FC00 to FCFF Four locations in this range are used by the Winchester system F...

Page 20: ...r addresses 4O to 43 ie output pin 15 goes low when the low order address is 40 41 42 or 43 IC7 is another 3 to 8 line decoder which takes the output from IC6 and CNPGFC and 1MHzE as enable inputs The 2 least significant address bits A0 and Al are decoded along with R NW into the required 5 separate signals shown above Y0 pin 15 is read data R NW 1 Y4 pin 11 is write data R NW 0 Y1 pin 14 is statu...

Page 21: ...fer which is enabled by Y0 of IC7 which is the read data signal see 5 3 1 The control signals used by the SCSI interface are available for reading by the host microcomputer They can be latched into IC4 an octal transparent latch when it is enabled by Y1 of IC7 The control signals appear on the data bus in the following positions D0 MSG Dl BSY D2 0 D3 0 D4 NIRQ see 5 3 1 D5 REQ D6 I O D7 C D All th...

Page 22: ...he defect list from the label in head cylinder byte format Option C is for entering the drive s parameters such as number of heads cylinders etc These options would be used for formatting a new drive or re formatting a drive which lacks a readable parameter or defect list for any reason When Superform is run it tries to read the defect list and parameter list from the drive and if successful it au...

Page 23: ...supply unit which sits at the back left of the case The power supply output cables are colour coded as follows black ground red 5V yellow 12V The power supply can be tested by measuring the 5 voltage between the black and red cables and the 12 voltage between the black and yellow cables The allowable voltage ranges are as follows 5V black and red 4 9V to 5 2V 12V black and yellow 11 4V to 12 6V Th...

Page 24: ...Address decoding The easiest way to test the address decoding is to execute a program which accesses the relevant memory location 7 2 1 FC40 read data Run the following program 10DIM P 10 20 30 a 40LDA FC40 50JMP a 60 70CALL a Test pin 1 IC3 with a scope and check that the waveform is not stuck either high or low It should look like the one shown in figure 4 7 2 2 FC40 write data Run the following...

Page 25: ... 40LDA FC41 50JMP a 60 70CALL a Test pin 1 IC4 with a scope and check that the waveform is not stuck either high or low It should look like the one shown in figure 4 7 2 4 FC42 write select Run the following program 10DIM P 10 20 30 a 40STA FC42 50JMP a 60 70CALL a Test pin 11 IC11 with a scope and check that the waveform is not stuck either high or low It should look like the one shown in figure ...

Page 26: ...g To test the SEL BSY handshake use the following program 10DIM P 20 20 30 a 40LDA 1 50STA FC40 60STA FC42 70 b 80LDA FC41 90BEQ b 100RTS 110 120PRINT USR a AND FF Press the BREAK key followed by OLD and RUN the program The LED on the disc controller board should illuminate and the result 2 should be printed on the screen after the assembler listing The result is the contents of the status registe...

Page 27: ...values of their terminating resistors Measure the voltage of each bus line in turn and make sure that none of them is stuck at 5V which would indicate a short circuit or at 0V which would indicate either that one of the buffers was enabled or that there was a short circuit The correct voltages are as follows 1 MHz expansion bus D0 to D7 and A0 to A7 should all be 2 5V SCSI DB0 to DB7 should all be...

Page 28: ...APPENDIX 23 ...

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Page 33: ... 0890 000 rubber feet 4 23 0805 003 switch dpst 250V 10A 1 24 0882 121 screws M3x6 pan hd posi 13 for case assy 25 0815 902 power socket 1 26 0800 983 conr skt jk kit 2 27 0882 972 washers M3 35 28 0882 902 nuts M3 2 for power socket and 37 way conns 29 0815 222 fuse 3A15 F HBC 20x5mmD 2 for item 25 30 0880 072 cable clamp 2 31 0201 921 fan 1 32 0882 144 screws M4x12 pan hd posi 4 for fan 33 34 08...

Page 34: ...Winchester Disc unit assembly diagram 29 ...

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Page 36: ...Winchester Disc unit wiring diagram 31 ...

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Page 38: ...LED connection diagram 33 ...

Page 39: ...47nF 16 A 11 0622 220 capacitor 22uF 16V 1 C2 12 13 14 15 0740 007 7407 1 IC16 16 0740 014 7414 1 IC15 17 0740 038 7438 2 1C13 1C14 18 0742 000 74LS00 1 IC12 19 0742 004 74LS04 1 IC9 20 0742 014 74LS14 1 IC8 21 0742 074 74LS74 2 IC10 IC11 22 0742 138 74LS138 2 106 1C7 23 0742 240 74LS240 1 IC3 24 0742 244 74LS244 2 IC1 IC5 25 0742 373 74LS373 2 1C2 1C4 26 27 28 0800 870 connector 34 pin header 1 P...

Page 40: ...Host Adapter PCB assembly diagram 35 ...

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