• The drive uses 4 x AA NiCd batteries for the emergency head retract. After 4 or 5 years the batteries generally fail, and if you forget to unload the drive when you power down the system or the power fails, you will crash the heads.

• If the heads crash and you get to the drive quickly, the heads will probably survive after a good clean. The pack will be a total loss.

• An easy check for the absolute air filter, is to open the bail door a place your hand over the air plenum on the left hand side. If the flow is low, and you don't have spare filters, use a vacuum cleaner to draw air in the reverse direction through the filter and you should get much better air flow. Be very careful with the plastic air duct between the absolute air filter and the plenum chamber for the disk pack. The plastic is prone to oxidation and it may fall to bits.

• If the fault lamp comes on when you power up the drive, then the lamp in the linear positioner has failed. They can easily be rebuilt using a 5 volt T1 sub-miniature lamp and 24 hour epoxy. Although I haven't tried it, a high intensity LED should work just as well (don't forget a dropping resistor to limit current to 20mA).

  If you get lots of seek errors or seek incompletes, then the lamp is probably on it's last legs (the envelope will be a silver colour). Check the Sine, Cosine and Limit signal amplitudes and offsets. If they are a long way off specification, then it is better to replace the lamp assembly, and redo the calibration.

• If the drive won't run up, check Bus AC and DC low. A common failure is the wiring to the micro-switch on the front door going open circuit breaking the interlock.

• If you are having problems with bootstrapping, load a trap catcher and manual bootstrap program ,and try to boot. After a few seconds, halt the CPU and check the registers :-

  	Location	Register	Bits	Description
  	===============================================
  	777400		Drive Status	15-13	Drive ID
  					12	Drive Power Low	
  					11	RK05
  					10	Drive Unsafe
  					 9	Seek incomplete
  					 8	Sector OK
  					 7	Drive ready
  					 6	Read/Write/Seek ready
  					 5	Write protected
  					 4	Heads in position
  					 3-0	Sector Counter
  
  	777402		Error 		15	Drive Error
  					14	Overrun
  					13	Write Lock Violation
  					12	Seek error
  					11	Programming error
  					10	Non-existent memory for DMA
  					 9	Data Late
  					 8	Timing Error
  					 7	Non-existent disk
  					 6	Non-existent cylinder
  					 5	Non-existent sector
  					 1	Checksum error
  					 0	Write check error
  	
  	777404		Control Status	15	Error
  					14	Hard error
  					13	Search complete
  					11	Inhibit bus address increment
  					10	Format disk pack
  					 8	Stop on soft error
  					 7	Controller ready
  					 6	Interrupt on done
  					 5-4	Extended memory address
  					 3-1	Function
  						0	Controller reset
  						1	Write
  						2	Read
  						3	Write Check
  						4	Seek
  						5	Read check
  						6	Drive reset
  						7	Write lock
  					0	Go
  
  	777406		Word count		0177400 at beginning of bootstrap
  						0 at end
  
  	777410		Bus address		0 at beginning of bootstrap
  						01000 at end
  
  	777412		Disk address	15-13	Drive select
  					12-5	Cylinder address
  					 4	Surface (head)
  					 3-0	Sector
  	777414		Data Buffer
  
  

There a few companies that make RK05 disk controller compatible emulated drives, try :- Thruput Ltd or ARRAID Data Storage Solutions