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LaserWriter II Fuser or PSU issue


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I have a LaserWriter II that I've been working on today. It wasn't picking up paper at all, but after putting a few rubber bands round the pickup roller it is now picking up paper with a 50% success ratio! Not great, but I'll take it for now! I'm able to print the service test page, which is great.

 

The main issue is that, when powered on, after a couple of minutes, it flashes the two red lights (paper out and paper jam). This means a fuser issue, which is also confirmed when I put in a IIg board, jumper pins 4 and 22 of the serial port to put it into diagnostic mode, and it also shows a fuser error.

 

I've gone through the troubleshooting steps of Table D on page 108 of https://vintageapple.org/laserwriter/pdf/Apple_Service_Guide_LaserWriter_Printers_January_1992.pdf, and the fuser checks out okay. I've also replaced it with a spare which also measures okay, and I still have the same issue.

 

The last step in that table is "Replace the power supply block", so I'm guessing that at 31 years old, the PSU just isn't able to supply the current needed by the fuser any more. Obviously replacements are almost non-existent these days (while there are a couple of 110v ones on ebay, there aren't any 240v ones), and any NOS ones might have the same issue. So I'm thinking I probably need to recap it.

 

Before I attempt this, I wanted to see if anyone else has had this issue? Did you fix it? Did you recap the psu?

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  • 2 weeks later...

I came here to see if there was a history on this as well. I've just picked up a LaserWriter II NTX that hadn't been used for 20 years ('worked last time I used it') and it's showing the same error code - the paper jam / paper out 'Service Required' status lights. I've ended up in the same spot as you @danda - Table D of the technical procedures. I was just about to start disassembly to perform the cleaning/lubrication procedures and visually inspect the PSU and DC PSU for cap leakage, and was wondering if anyone else had encountered this problem...?

Edited by desertrout
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The "AC Power Supply"  is a high failure item on SX engine printers (it causes the dreaded ERROR 50 on LaserJet IIs).

 

The part looks like the link: https://www.ebay.com/p/1204091741

 

The original part should have a squirrel cage style fan on it, while most replacements/remans like above have a standard fan. A part marked for a LaserJet II should fit the LaserWriter II no problem. Also, some of them eliminate the ozone filter.

 

Possible Part Numbers:

 

110V: RG9-0205-000 (last 3 digits vary on these)

240V: RG9-0206-000

 

The now defunct Printer Works site lists different types of power supplies for SX printers and has an ID guide:

https://web.archive.org/web/20041214060836/http://www.printerworks.com/Catalogs/SX-Catalog/SXPwrSuppBlkDiffs.html#0205

 

The 240V versions all are one digit higher then the 110V: https://web.archive.org/web/20041217140635/http://www.printerworks.com/Catalogs/SX-Catalog/110SXPwrSuppBlk.html

 

Found one RG9-0206 on ebay UK, confirm fitment with seller:

https://www.ebay.co.uk/itm/HP-RG9-0206-000CN-AC-POWER-MODULE-USED/233505086840?hash=item365dfcdd78:g:oPoAAOSwUvxeoNo4

Edited by NJRoadfan
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Thanks @NJRoadfan that's great info. I wasn't aware of the SX engine, that's very helpful.

 

I was fussing around with the machine some more, and it seems like the heater bulb just isn't getting enough juice. Not scientific, I know, but the troubleshooting procedures don't seem 100% relevant, not surprising with a machine that's been sitting in a basement for a couple decades. On a cold start, the bulb will light up, but on restart it won't, or it'll be faint. I opened the DC PSU and it's bit of a wet mess, so that'll be my first task - just baseline the thing, I won't bother measuring anything. New caps, a good cleaning. Then we'll see what happens after that.

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I haven't seen problems with the DC power supply in these. Usually if that is dead, the whole printer would play dead since it powers the controller board. The high voltage supply (the one with the green dial) is what powers the laser assembly. Your printer's symptoms point to the AC Power Supply (the assembly with the power switch and mains plug on it) which directly powers the fuser.

 

I've always suspected the AC power supply in these all managed to cook themselves to death due to poor cooling. They have been a high failure part early on to the point that replacements were well under $100US even by the late 90s. Back when I fixed printers, we had a bench spare AC power supply and fuser assembly to swap in to quickly determine the problem. We always kept stock of those two parts since we frequently replaced them.

 

Otherwise the Canon SX engine was pretty solid and hard to kill. HP stopped making toner for the Laserjet II/III ages ago in an attempt to get people to replace their 20(!) year old printers with little success. They may only be 8 pages per minute and 300dpi (before tricks like HP RET or Apple's PhotoGrade), but they were plenty for the average user.

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I've ordered a new Triac and capacitor for the PSU, and will report back once I've replaced them. Apparently those are the most likely parts that cause this issue. Here's hoping, anyway! I ordered them about a week ago but shipping here is very slow at the moment.

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On 1/3/2021 at 10:18 AM, NJRoadfan said:

I haven't seen problems with the DC power supply in these. Usually if that is dead, the whole printer would play dead since it powers the controller board. The high voltage supply (the one with the green dial) is what powers the laser assembly. Your printer's symptoms point to the AC Power Supply (the assembly with the power switch and mains plug on it) which directly powers the fuser.

 

I've always suspected the AC power supply in these all managed to cook themselves to death due to poor cooling. They have been a high failure part early on to the point that replacements were well under $100US even by the late 90s. Back when I fixed printers, we had a bench spare AC power supply and fuser assembly to swap in to quickly determine the problem. We always kept stock of those two parts since we frequently replaced them.

Yeah, I was thinking I'd jumped the gun here and you've confirmed it I think. I'll pulling caps on the DC PSU and they're all testing fine, and what I swore was electrolyte appears to be something else... it looks like electrolyte, and kinda smells like electrolyte, and IPA swabs turn brown with it, but there doesn't seem to be any source for it. I may replace them anyway since I'm in here but, yeah, I hear you.

 

21 hours ago, danda said:

I've ordered a new Triac and capacitor for the PSU, and will report back once I've replaced them. Apparently those are the most likely parts that cause this issue. Here's hoping, anyway! I ordered them about a week ago but shipping here is very slow at the moment.

For the AC PSU?

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9 hours ago, desertrout said:

For the AC PSU?

Yes, the AC PSU. It has a triac to control voltage to the fuser, along with a single electrolytic capacitor. The key is to Google for "laserjet ii error 50" and there you'll find a few pages of people talking about this. Some people say the triac goes bad, others talk about the capacitor, and there's also a solid state relay in there too that can apparently be an issue.

 

I'm replacing both the capacitor and the triac. I would have replaced the SSR except I couldn't find a replacement for it and I lack tools to do surface mount soldering properly. So I'm hoping that's not the issue!

 

I'll update here once I've done the replacement with the results!

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I disassembled the printer and cleaned out all sensors and connections, reassembled, also reinstalled the caps I had removed from the DC supply, the printer now seems to start okay - roller test, fuser bulb lights up bright and shuts off as it should, green indicator flashes for a bit, then is solid - but no test page prints and then the paper jam / paper out indicators flash for the 'Service Required' message.

 

When I follow the troubleshooting charts, I end up at 'replace the controller i/o board'... which is unhelpful. I've yet to test voltages, but I'm wondering if there's something else I should be looking at instead?

 

 

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Flashing green light likely indicates the controller is working and processing the startup page to print, only to fail when the printer attempts to heat up the fuser. Failures in the AC power supply can be intermittent. You should be able to connect to the printer via AppleTalk and query its status with the LaserWriter driver. If that communication works, the controller board is likely fine.

 

One thing to note about the Apple Service Source is that its really basic and doesn't seem to call out the AC power supply as a trouble spot. HP's service manual for the LaserJet II/III has a far more detailed testing procedure for dealing with the issue. It also calls for replacing the AC power supply before replacing the DC power supply.

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Cool - thanks for the insight. I was doing some more testing last night, and it does in fact seem the AC supply is indeed the root of the issue here, as you've been saying all along. The startup behaviour is inconsistent - sometimes the fuser seems fine and the machine will come close to printing a test page (but doesn't), other times the fuser clicks off or there's a flash from the AC unit (I watch it with the top cover open and overriding the toner / top cover switches) ... so yeah it seems pretty clear to me now.

 

I can indeed select the printer in Chooser, so it would seem that the I/O board is probably ok. I'm not sure about querying its status with the driver, not sure what that means - I'll check the manual.

 

One of the caps in the AC supply (a 25V 22uf) had leaked a bit and it tested bad. I've yet to test the triac, but even if it's shorted I'm wondering about whether or not I can find a modern replacement (800V / 10A isolated tab), or its companion optoisolator... but one step at a time. 

Edited by desertrout
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Posted (edited)

The triac I'm replacing it with is the Q6015L5TP which is a 600V 15A one I'm hoping will be suitable. The optoisolator is a "S21ME4 Sharp X7" and I'm not really knowledgable enough to figure out a suitable replacement for it. If anyone knows more about this or a suitable replacement, I'd be interested! In the meantime, I'll be replacing just the triac and capacitor when they arrive, and hoping for the best.

Edited by danda
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  • 2 weeks later...

The triac and capacitor arrived today, and after replacing them in the AC PSU (which Apple call the "Power Supply Block"), I'm delighted to report that I have a fully functioning LaserWriter II!

 

I've had this printer sitting here for over three years now, so it's great to have it finally working. I've also got a box of all the different IO boards for the LWII (SC, NT, NTX, g and f), which I'm now going through and trying. I also seem to have three NT boards, so if anyone needs one, let me know!

 

The pickup roller still needs some attention as although manual feed works perfectly, loading from the cassette always takes several pages at once, but that's an issue for another day I think!

Edited by danda
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Great to hear! I'm assuming the capacitor you replaced was on the daughter board (or whatever it's called)? I don't see any capacitors on the lower board...

Also, I'm very curious to know what values the two resistors are next to the triac... would you happen to know or have a pic? I believe the ones I have here are 23 and 150 Ohms

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Yes, it was the 22uF 25v capacitor on the secondary board that I replaced. It was only today I noticed that there's also a 10uF 50v capacitor on that board too, but I didn't have a replacement for that so I just left it as is.

 

For resistor values, I don't have a picture but I did write them down. R102 is a 150Ω (brown green brown slilver), and R103 is 22Ω (red red black silver). However, when I measured R102, it measured 50Ω. This could be because I was measuring it in circuit, or my multimeter's battery dying on me, but I didn't replace either resistor and it still seems to work, so I'm not complaining!

 

Also after testing, all of my IO boards work, which is fantastic! The IIf had some bad RAM but after replacing that it worked too. So now, in a way, I have all five of the different models of LWII :)

 

After this success, I'll have to take a look at my other LaserWriters! My two Pluses need their pickup rollers repaired, and all three of my Personal LaserWriters don't even power up at the moment...

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  • 2 months later...
  • 68kMLA Supporter
On 1/16/2021 at 8:27 PM, danda said:

Yes, it was the 22uF 25v capacitor on the secondary board that I replaced

 

Hey, thanks for linking me to this thread! I have an IINT with the exact same symptoms, I haven't tested the fuser yet in an electrical fashion, but swapping a couple of PSU components sounds far easier and cheaper. Will get some parts ordered and see what happens.

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  • 2 weeks later...
On 3/24/2021 at 12:31 AM, Paulie said:

I haven't tested the fuser yet in an electrical fashion

Testing the fuser is actually easy, I think it's just a continuity check and a resistance check. Also if yours is dead, I think I may have a spare here too.

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