I am working on a Xerox 470 with print. I keep getting 9.334 error codes. I hook the pws to the machine and run the Xero setup and get 9.338 failure to converge. I replaced the Xero Module about 3 times with different brand new modules. I replaced the Developer and toner dispenser unit. I replaced the scam board. I tried a different developer HV board. I replaced the voltage distribution board. I cleaned the contacts on the Charge and Transfer boards. I checked for continuity on the wire harness to the developer unit. I repalced the BTAC sensor. I measured the ohms on the fuser fan and get 1.6 meg ohms. I thought this might be a problem, so I measured the ohms on a working machine and get 1.8 meg ohms so I don't think this is the issue. I also get infinate ohms on the fan if I reverse the leads. The only thing I have not relpaced is the Primary and secondary Power supply and the charge and transfer boards. What do you think the problem is?? Could it be software? I also tried a new Ros assembly and set the numbers up. I can turn off the machine and let it sit for a while till it cools down. When I power up and use the PWS to run Xero setup it will sometimes make it through or fail at the end with 9.338 failure to converge. After this happens, I can try to run it again and I get Tone Up / Tone Down failure 9.334. After it's hot it will keep failing at 9.334 Tone up / Tone Down after 2 min. of running the xero setup with the laptop. It never makes it through setup in customer mode. I have to turn the machine off and on after it fails. I can then make about 1,500 copies before it fails again. Sometimes it makes it through the job. It will complete the job and then say Adjusting. It never makes it through adjusting. Always get a 9.334 code. The copies look good, but other times will tone up a little after you run it for about 20 min. (slight background). I have no idea what to do next. I am going to take a shot in the dark and replace the primary and secondary power supples today. If that does not work, I am going to put a UI and Main board (the whole module with different drives) in the machine to see if it will setup correctly. Also, When I power the machine up It always says power off and then on again. I have to power off and on about 4 times before it will boot. Any Ideas? Going crazy.
Thanks in advance,

acribari

Well, I tried the Secondary and Primary Power supply.  No change.  I let the machine get cool for about 10 min.  I power it up and run it through Xeographics with the laptop and it makes it through.  The 50% is about 1 or 2 over max target and the 87% is about 19 (max is 11).  All the rest of the numbers are right about where they should be.  After it makes it through Xerographics, I run the Xero Exersice and it passes.  Now it's warm after these two runs.  I run it through xero setup with the laptop a second time but this time it fails at tone up / tone down with error 9.334.  I run the Xero exercise test and it says replaced developer unit or Toner dispenser. 

I turn the machine off and let it sit for 5 min.  and it cools down.  I power back up and run Xero setup with the laptop and it makes it through with no trouble.  After this, I get out of Diag. and go back into customer mode.  I make 200 copies so it gets warm.  It makes good looking copies.  I try to make another 200 copies and it says please wait adjusting.  It never makes it through adjusting.  It throws code 9.334.

Something is getting hot somewhere.  A chip or board.  I replaced everything except for the boards in the computer bussel and UI.  Can it be the UI or The Main board in the bussel?  Which one of the boards controls copy quality in the Computer bussel? or is it the UI boards that controls this setting?  It has to be a board getting hot.  I don't think it is software because it makes it through Xero setup when it is cooled down and the copies are beautiful.

Any help would be great.   

PS.  the toner concentration nubers start out at about 47 and go down to about 38 (where it should be) when its cool and I run setup right away.  It passes this way.

The toner concentration numbers are .03 or .91 or some decimal when the machine is hot and I try to setup Xerographics with the laptop.  It fails with 9.334.  After I power off and let it cool down, I can power up and it runs right through Xerox setup with no trouble.   

searchlite says change the p/r module drive assy or just the backer bar (cheaper option)
you could try it.

best of luck, i hate those plastic pig machines

Fixed:  Replaced the Developer unit again and installed new developer matierial.  Ran right through setup and prints fine now.  What a nightmare.