I've been working on an HP M5035 MFP Printing blank pages. Parts replaced: Laser/Scanner, DC Controller, Formatter, HVPS, LVPS, transfer roller, fuser. Checked high voltage contacts/ OK. Checked laser/scanner shutter mechanism/ OK.Also tried with 2 toner cartridges.Any ideas?

Hi,
I think you are since the dc controller only controls paper movement and nothing else. A 49 error is a firmware error and has many causes from applications, network and just defective formatter. If the errors occurs with the printer not connected to anything, then the formatter would be the logical issue if the firmware has been updated. Keep in mind having a jet direct card in the slot can cause the error, so the only true way to test is with everything removed with the exception of firmware, memory and power. Also keep in mind that if the 4250/4350 series power is derived from the lvps and not the dc controller. Also with this model the embedded jet direct card is known to occasionally have issues. When you upgrade the firmware for the formatter it also upgrades the firmware on the embedded nic card. Again the only true way to test would be to disable the embedded nic card on powerup.

Read more... HP Support document HP Support Center and HP Printer Support

HP Service Manual Library

Download the manual here, this is your best option and will show you step by step.

The DC Controller board is going back and causing the laser beam to run continuously causing the photosensative drum to be in a neutral state which causes the black pages.

Are you checked cartridge contacts left side of the cartridge bank, you can observe three flexible plastic shells representing the contacts to cartridge,, check them there is the problem....

First, this model is not color laserjet, only black.
HP LaserJet M5035 MFP
30.1.34 Cable error or loss of communication with the formatter.
1. Turn the device off and then turn the device on.
2. Make sure that the ribbon cable between the scanner control board and the formatter is not damaged and is correctly seated.
3. Make sure that the hard disk drive on the formatter is connected correctly and that the hard disk is functioning correctly.
4. If the message persists, replace the scanner control board or replace the formatter.

52.00 = laser/scanner error

1. Turn the device off, and then turn the device on.
2. Reseat the connectors between the laser/scanner and the dc controller PCA (J801 and J321).
3. Replace the laser/scanner assembly.
4. Replace the dc controller PCA.

Laser error
You may have to replace the laser/scanner assembly or the DC Controller
Sorry

HP 4550 Color Laserjet Printer - Blank or white pages :

01. Your software application is sending an extra page-eject command.

02. Check the software’s printing configuration information. There is a problem with the network configuration.

03. Some sharing devices on networks may generate a blank page as a separator.

04. Check with the network administrator.

05. The printer may be feeding two or more pages at once because the paper is difficult to separate.

06. The sealing tape has been left in the toner cartridge.

07. The toner cartridge is empty or defective.

08. The laser scanner door does not open properly.

09. Remove and reseat the toner cartridge.

10. Check the laser scanner shutter door for proper operation.

11. The toner cartridge guide is damaged,
improperly positioned, or missing.

12. There is no transfer roller voltage.

13. Perform the Half Self-Test Functional Check to check all other electrophotographic processes.

14. Replace the transfer roller if necessary.

15. The high-voltage connectors are mounted on the high-voltage power supply (HVPS) PCA and protrude into the toner cartridge cavity.

16. Check the springs for functionality. Clean if dirty; replace if defective or missing.
The HVPS PCA is defective.

17.The DC controller PCA is defecti
There is no drum ground path.

18 Check the drum ground.

19. The laser scanner cable assembly is defective
.
20 The page length and margins are not set correctly for the paper size. Verify that the ribbon connector at J1307 of the HVPS is
properly seated.

21. If the HVPS has been removed recently, verify that the ribbon connector from the DC controller PCA to the HVPS is properly
seated at both ends..

22. Verify that the photoconductive drum is rotating properly. Perform is the drum diagnostic test to visually observe if the drum is rotating.
23. OR using a felt-tipped marker place an index mark on the edge of the drum outside the image area. Turn on the printer (wait for
drum rotation to occur), and then look to see if the drum has
24. moved. If the drum has not moved, investigate the mechanical
and electrical drum rotation circuitry and movement mechanisms.

25. The imaging drum shutter may not be retracting. Replace the imaging drum.

26. Lst but not the least, please fry to have the Printer int the Setcie

27. Use only HP Authorized Genuine catridges only

check printer door, there is a small plastic piece wich pushed down (to open) lasser scaner cover. if this piece is broken you can get blank page

Replace the transfer belt. Known issue with this machine.
Hope this helps