you sent i the link to the document HP LaserJet 1200 Service Manual I had got it, your document sent to me has no schematic electriction, i need to find the schematic electriction of printer: HP LaserJet 1200 and Canon LBP 2900, thanks
LaserJet 1200 service manual book said only the general circuit, do not go after the details of electronic components in the HP printer, you know what I say ? thanks
Mr Dongtrien, HP will not provide the in and out of its circuitry, bill of materials and board design. Probably you can get the service manual or some basic circuit details which help for any trouble shooting as someone has told above.
We will be grateful if you can make your need clear without rolling over the same question again and again.