this says they have one for sale http://www.com-com.co.uk/HP/parts/RK05K.ihtml?pp=1~source=com-com.co.uk On 12/10/09, Guy Sotomayor <ggs at shiresoft.com> wrote:

http://www.tamayatech.com/parts.php?g=RK05KAC there they have one for $265 also here they have a whole list here http://www.tamayatech.com/partsindex/dec_055.htm On 12/17/09, Brad Parker <brad at heeltoe.com> wrote:

On Fri, 1 Jan 2010, Tom Uban wrote: What about stealing the chip out of one of those recordable greeting cards? Peter Wallace

On Jan 1, 2010, at 3:04 PM, Tom Uban wrote: The ISD series of chips from Winbond will do the trick nicely. They store sound in what amount to analog EEPROM cells. I've designed with them; they are easy to deal with and work very well. Versions are available with pushbutton-compatible control signals, I2C, and others. Some have "address" pins so you can have multiple addressable messages. They are more or less self-contained; they require very little support circuitry. You can have a basic record/playback circuit up and running in an hour or two. Look at the ISD2560, for example. -Dave -- Dave McGuire Port Charlotte, FL

ISD audio chips, look for that, winbond used to manufacture them.

http://www.isd.com/hq/enu/ http://www.isd.com/hq/enu/ProductAndSales/ProductLines/ConsumerElectronicsI… On 1/1/10, Dave McGuire <mcguire at neurotica.com> wrote:

It's all done with that optical transduce (the glass scale, the lamp, and a couple (or is it 3) photodetectors under the carriage). IIRC it moves the heads towards the spindle, then as soon as it gets a valid signal cylinders are then found by counting pulses from that transducer. AFAIK the microswitch is only used to disconnect the emergency-retract battery when the heads are fully retracted. It's not part of the positioner system, it wouldn't be repeatable enough. Did the drive work properly after re-fitting that glass scale? Misalignment (or mis-setup) of this will cause the head positioner to malfunction. I think you can disable the servo with the toggle switch on the amplifier PCB (on top of the PSU), move the carriage _caerfully_ by hand (with a disk loaded and spinning, of course), and look at the waveforms. This could be a problem in just about any part of the servo analogue electronics. The good news is that it's a pretty simple positioner servo (no feedback form the disk itself, for example), and there shouldn't be any prolems getting components. Which one? I am wondering if you have failed power transsitors on the servo amplifier board that are overloading one of the power rails. Ma be worth checking. -tony

I don;t know what manuals you have, I am working from a printset (only). I find it much easier in the end to start from the schematics (which are probably the most accurate representation of the actual device). I've found too many erorrs and unclear statements in circuit descriptions (not just DEC!) over the years... No, 3 sensors. SIN, COS, LIMIT. There are 6 wires, hut the 'L' side of each sensor is earthed (check the chassis wiring diagram and the backplane wirelist in the printset). The 'H' side of the 3 sensors go to the servo analogue/preamp PCB I think you're getting confused by DECs (confusing, I'll agree) terminology. The limit switch -- the microswitch on the positioner -- produces the HOME L signal (it also, as I thought, disconnectes the emergency-retract battery). The HOME L signal is used as part of the spin-up enable circuit (I think it won't try to start a drive if the heads aren't home), and also to disable the servo REV signal on a normal retract. The OUTER LIMIT signal comes from the servo analogue/preamp board, and is derrived from the LIMIT optical sensor. Not a switch. I suspect that is the problem. Those 3 signals are critical to the operation of the positioner. Look at the G938 schematics in the printset. E14 is the the servo summing amplifier, it drives the power amplifer (on a separate PCB), otuput on pin BU2. It can take a velocity signal from E12 (for seeks) and a position signal from E6 (derrived from the SIN POSITION signal, aka SIN H) for holding on track. Also on that schematic see how the COUNT PULSE FWD and COUNT PULSE REV signals are produced (they are the track crossing signals to drive the current cylinder counter) and the OUTER LIMIT L and INNER LIMIT L signal. My experience (with anything, not just RK05s) says that if you have a problem, correct it. The drive (in this case) can't possibly work if the outputs from the optical transducer are incorrect. Disable the servo drive(put the switch on the power amplifer PCB down) and look at TP2 (pin AM1), TP4 (AS1) and TP10 (AJ1) while moving the carriage by hand (disk loaded and spinning, or you'll ruin the heads!) Next trap for the unwary. The 2 15V regulators (+ve and -ve) are _indentical_./ The mains transformer hs 2 secondary windings, both feeding bridge rectiifers and smoothing capacitors. One provides the +ve voltages (+5V, +15V), the -ve side of that bridge is logic ground. The other supplies a 15V regulator unit, and the +ve output of the regulator is connected to ground. The result is that the -ve side of the bridge/capacitor (and the common point of the regulator) is at -15V wrt ground. It's a swtiching regulator of course. What seems to have failed? -tony