Laserjet II ntx Error Lights on power up

[rickrob]

Picked up a Laserjet II ntx-- Powers on, then displays two red flashing LEDS, (Paper Jam and Paper Out)

When it powers up, I can hear a click then a second click the printer goes through the warm up and then shows the error

I know the fuser heat bulb is good. I'm wondering if the printer is shutting the fuser off.

I will check the fuser using the technical service procedure in the manual, and then check the DC power module.

Is there anything else I can check?

 

[IlikeTech]

according to pages 445 and 446 of the Dead Mac Scrolls say it is the high limit switch or thermostat.

 

[rickrob]

I checked the thermistor-- seems good. Bulb is OK-- I have seen it come on then go off.

I read 2.6 ohms across  connector J103 on the fuser.  Apple service procedure says continuity across J103 indicates bulb and thermistor is good.

Did a resisitance check on the fuser on connector J331 pins 4 and 5-- read  995K Ohms.  Apple says 1 M Ohm to 1.6 M Ohm is good.

Do you know where the high limit switch is?

 

[IlikeTech]

Unfortunately not, what does the Apple manual say?

 

[rickrob]

Found it.  There's an Elmwood Thermal Sensor/Thermistor behind a cover plate.  That's good too. Took it out, heated it up and it went to open. closed again when cool. I think the fuser is OK.

 

[rickrob]

Found a bad capacitor in the AC power block -- on the controller card.

 

[TimHD]

Found a bad capacitor in the AC power block -- on the controller card.

I had similar scenario with my NTX. Did replacing the AC power block capacitor fix everything? Where is it located so I can test/replace?

 

[rickrob]

I had similar scenario with my NTX. Did replacing the AC power block capacitor fix everything? Where is it located so I can test/replace?

Yes, When I replaced that cap, the problem went away.  IT was a 22uF, 25V electrolytic cap. I also replaced the 10uF 50V cap while I was there. You have to pull the covers, then remove the AC power block

(4 screws)

Then remove the fan shroud and fan,  and pull the circuit boards from the AC power block.  The caps are on the small controller board.

 

[TimHD]

Yes, When I replaced that cap, the problem went away.  IT was a 22uF, 25V electrolytic cap. I also replaced the 10uF 50V cap while I was there. You have to pull the covers, then remove the AC power block

(4 screws)

Then remove the fan shroud and fan,  and pull the circuit boards from the AC power block.  The caps are on the small controller board.

Do you mean the "[SIZE=9pt]High-Voltage Power Supply" [/SIZE]per the Service Source manual, or was it on the DC board or DC power supply? (Haven't been inside the iintx for a while - recall it was quite a disassembly but I went all the way in to check everything as best I could.

 

[rickrob]

It's next to the fuser, and the AC power cord plugs into it.  Small assembly, right in the corner with a fan sitting on top of it.

 

[rickrob]

Page 67 of the Service Source-- "power supply block".