Tungsten Halide 'fuser' lamp from LASER printer - Page 1
Forum section: electronics / beginners

author: lordvader88
author_rank: Frequent Contributor
timestamp: April 17, 2018, 11:07:08 pm
content: I found a laser printer on the sidewalk today, and promptly took it apart. 1st 1 of them I've scrapped. It's from 2004 and it almost seems there's less to it than an inkjet I just took apart.So I found a Tungsten lamp inside, runs off 120V, from a thyristor somehow. Anyone know the typical spec's on 1 of these lamps ? And a basic circuit to run 1 ? Can I use a basic triac circuit ? IDK how these work.Could it be used to remove/reflow SMD parts ?

author: ovnr
author_rank: Frequent Contributor
timestamp: April 17, 2018, 11:29:29 pm
content: Quote from: lordvader88 on April 17, 2018, 11:07:08 pmEh, you can use anything that gets hot enough to do SMD work. Not a brilliant idea though.It's just a heater to fuse the toner to the paper. Circuit-wise, give it the power it wants; there's nothing to it.

author: lordvader88
author_rank: Frequent Contributor
timestamp: April 17, 2018, 11:59:40 pm
content: Does it need any kind of current limiting ? I read they start low ohm's, mine is ~2-3ohm, and that it increases to maybe 40-5- when hot. I have no ideaa the power rating of this. To late to map out the thyristor circuit, but its SM16JZ47 600V 16A , and there's a 10A thermisistor.

author: ovnr
author_rank: Frequent Contributor
timestamp: April 18, 2018, 12:08:33 am
content: It's just an incandescent bulb; it'll do incandescent bulb things, like have a substantial inrush current. I expect it was soft-started (using the thyristor) in the printer.

author: ovnr
author_rank: Frequent Contributor
timestamp: April 18, 2018, 12:56:53 am
content: Quote from: wilfred on April 18, 2018, 12:48:32 amReasons it's not a brilliant idea, beyond being a bad pun:* IR reflow - which this easily becomes - heats components somewhat unevenly; a black IC will absorb a lot of light, while the shiny leads don't.* Waving what's effectively a lightbulb over a board to solder it definitely lands in the "sketchy" category of things.* You're only heating one side of the board, leading to excessive thermal stresses. It'sfine, but it's not optimal.

author: drussell
author_rank: Super Contributor
timestamp: April 18, 2018, 01:49:01 am
content: It's a lamp used as a heating element with a simple feedback control loop to control the temperature.

author: Ian.M
author_rank: Super Contributor
timestamp: April 18, 2018, 02:34:38 am
content: If you are going to try DIY IR reflow, its easier to use 50W 12V Halogen spotlight bulbs, with Aluminum or fully metallized reflectors, not the diachronic reflector type that's designed to block most of the heat at the front glass and let the heat out the back. It will be far more controllable and more suitable for small boards than an ex-printer fuser lamp + you can still get replacement bulbs relatively easily.I think you'd want two bulbs to do it right, both with dimmers to adjust the heat. One on a flex arm to use from the top, and the other mounted facing up flush in a close fitted hole in a heat resistant stage to use to preheat the underside of the section of board you are working on.

author: MosherIV
author_rank: Super Contributor
timestamp: April 18, 2018, 06:41:07 am
content: Drussell is mostly correct.It was not just a simple control loop for temp. There were many parameters because it was designed to melt toner to paper, not just heat the fuse roller.If the lamp has more than 2 connections, that is because the lamp is split to heat different parts of the roller for different size or orientation of paper.

author: lordvader88
author_rank: Frequent Contributor
timestamp: April 18, 2018, 10:35:33 am
content: It has just 2 connectors.IDK what to do with it besides try to melt solder, too hot for a benchtop lamp

author: ovnr
author_rank: Frequent Contributor
timestamp: April 18, 2018, 11:47:49 am
content: Quote from: lordvader88 on April 18, 2018, 10:35:33 amThrow it in the bin; it's not very useful.

author: MosherIV
author_rank: Super Contributor
timestamp: April 18, 2018, 07:26:57 pm
content: QuoteI do not remember the max temp achieveable with these lamps, probably only 250°CDefinitly too cold to melt solder.Yes, the lamps are designed for heat not light.I forgot to get myself a fuser module before I left Xerox, I wanted to use one to melt toner onto copper clad board for pcb making.They are good for heating.Fyi, I do not think you can run them for long fully powered, they were PWMed in the copiers to maintain roller temperature.

author: james_s
author_rank: Super Contributor
timestamp: April 18, 2018, 07:49:00 pm
content: In the original assembly running them continuously would quickly overheat the rollers, but the bare lamp is essentially a standard linear halogen lamp, you can use it like you'd use any other halogen lamp. Printer use is actually somewhat hard on these things because they don't get hot enough for the halogen cycle to work properly. I've replaced them a few times and found the old lamp was completely black inside.