Personal LaserWriter LS won't turn on

[Mike Richardson]

I got this a few days ago from the recycler. Yesterday it turned on but now it won't

Sometimes you see the green light flash on and off quickly, but that's it.

Maybe some bad capacitors?

 

[wally]

Some things you can do: Try another power cord, and make sure the contacts on the IEC connector are corrosion free. Open the access door, remove the two screws securing the top cover assembly and lift it off. Look for the hidden recessed unmarked green circuit breaker reset button on the back of the power supply and reset it. There is a large multi-section interlock switch you can wiggle vigorously also.

The next things are harder and many screws are involved, get some tape or containers and a marker so you can keep track of what screws go back where: disconnect power, remove the power supply and open it up. With an ohmmeter you can check the power switch, circuit breaker and interlock switch to see that they electrically work.

The next things are harder still: Use a voltmeter across the output of the bridge rectifier from +D101 to -D101 (outermost pins) to make sure the large 200V electrolytic has discharged thru its bleeder resistors. Then carefully remove the PC board. For the Sony RH3-2127 power supply replace C109 47uf 35V, I have seen an open one cause a no start. For the Sony RH3-2101 power supply replace C107 47uF 25V and C108 100uF 50V.

If there still is a problem check the inrush current limiter TH101, it looks like a fat ceramic sitting next to the bridge rectifier. It is supposed to go from 8 ohms cold to as low as .17 ohms warmed up (4A test current I think) in approx 83 seconds for soft start surge suppression, So check that the cold resistance is less than 10 ohms. It is harder to check the warm condition which probably draws less than the limiter spec sheet 4A, but if you make some notes on test points before putting the PCB back you can run the power supply with the cover off connected back to the printer and verify that big electrolytic should have about 155V across it in the warmed up ready to print condition. If you see 155 to 162V, TH101 is not causing excessive voltage drop.

Shorted caps on the output or anywhere on the load side could cause overload shutdown but so far I have not seen shorted caps on my printers.

 

[Mike Richardson]

I got it to turn on. All I did was take off the cover and it decided to turn on and work.

It was printing with the toner that was in it but the prints were very poor. I decided to try a new cartridge. At the same time I put the cover back on.

Big mistake. The paper feed changed when I put the cover on and when I printed, not only did it accordion jam, the new cartridge shit toner everywhere AND some piece of rubber related to the paper pick up broke off.

Now it won't pick up paper and it thinks there is a perpetual jam.

At least I have two others I can try, although the new cartridge is probably ruined due to being caked in toner now. I'll see if I can get any $15 HP toners from Goodwill.

 

[Dennis Nedry]

Check out the Apple service manual for that printer. You may still be able to fix it, maybe a little glue on the pickup roller.

 

[wood_e]

I think you can pick up new rollers pretty cheap.

 

[wally]

To some extent cartridges are self cleaning when inserted into a working printer and cycled. But you can do some manual cleanup to avoid soiling other printers. Work well after sunset outdoors (so there is no UV nor bright light) or someplace dim indoors but where you can make a mess then cleanup. You will need a supply of clean cotton balls (sterile is overkill).

First figure out which way the drum has to rotate with the paper movement. Clean the outside toner mess best you can with an old paint brush over newspaper, then flip open the drum shutter and secure it open with tape.

Using the cotton balls gently stroke the drum surface to pickup most of the toner. Discard each ball when the initial working side is dirty, do not reverse the ball and wipe fingerprint oil onto the drum. Rotate the drum using the gear on the end in the proper direction only to reveal more drum surface that may need wiping. Do not press hard (danger of scratching the drum), just try to dust most of the excess toner off. There is an internal squeegee system that will try to remove the rest over the next few print cycles.

Do not inadvertently get any breath moisture or cleaning fluids on the drum, which needs to have uniform highly insulating properties at the surface. If you wipe down the outside of the cartridge with anything damp, there could be tiny droplets that get past the shutter and spot the drum surface so be cautious.

The paper pickup cam thing is a pair of textured surface wide rubber bands stretched over flanged plastic cams. If you have enough rubber left, you can rotationally shift the rubber on the cam to put intact and unworn rubber over the highest points of the cam, the only part that matters. Some disassembly and reassembly will be required and you need to mark the original rotational alignment and get it put back right. If you can get new rubber, better still.