Scotch TL901 Laminator PCB etching heat modifications

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Jarod
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Scotch TL901 Laminator PCB etching heat modifications

Post by Jarod » Tue Nov 20, 2012 8:14 pm



I just got my laminator (Scotch TL901) to do toner transfer pcb etching with.

I am printing my toner with a HP Laserjet 2200-something (It has the duplexer and ram upgrade I think)

I've decided to try the parchment paper method with the laminator, I was doing magazine paper but it was tough to work with and the results were very poor (could be the clothes irons fault)

So here we go. photos of so far: Laminator warming up and pcb prepped and wrapped with the parchment paper with toner on it
Attachments
IMG_0154.JPG
IMG_0155.JPG

Jarod
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Re: PCB Etching with Laser printers and Laminators

Post by Jarod » Tue Dec 11, 2012 7:57 pm

So I've attempted etches several times. the parchment paper works awesome. however the tl901 doesnt get hot enough as some of the toner doesnt bond, leaving a spotty etch which then doesnt conduct well or at all and is difficult to solder to.

In an effort to fix this I've disassembled the unit by removing the screws from the bottom:
IMG_1330.JPG
Since it has dual heat settings I figure it should be possible to add a 3rd:
IMG_1331.JPG
Thermal fuse in big oval, thermistor in small circle.
Thermal fuse is rated for 188C
IMG_1333.JPG
Closeup of thermistor. its touching the roller?! seems like that could wear it out...
IMG_1335.JPG
Testing voltage vs heat.
IMG_1337.JPG
Heres my findings:

7~V = 70~F
2.6V = 220F (3mil setting)
1.84V 250F (5mil setting)

so on 5mil we're barely hitting 121C... Ideally we need 145-150C

I'm thinking an additional resistor inline with the wire should bump the temp up a tad, then figure out some way to enable and disable the resistor via external switch (hoping to keep laminator functionality too)

Tom
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Re: PCB Etching with Laser printers and Laminators

Post by Tom » Tue Dec 11, 2012 10:59 pm

I've thought some more on this. I think I actually want a resistor bridging the wires, to keep the voltage slightly higher thus fooling the controller into thinking the rollers aren't hot enough.

I'm not great with electrical theory, so I may be wrong. If this is the case then a spst switch with a resistor across the thermistor wires should allow for easily turning PCB mode on and off.

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Re: PCB Etching with Laser printers and Laminators

Post by Jarod » Fri Dec 14, 2012 8:53 pm

nope. A 1.2k resistor inline with the little black thermistor wire is just the ticket. gets up to right about 292-298F which is about 144C so that's in the 140-150C range ideal for toner transfer.

I'm going to test it right now, then report back if its improved.

As a note this laminator is on sale at amazon right now for $16.99 Link to the store page with it

Jarod
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Re: PCB Etching with Laser printers and Laminators

Post by Jarod » Thu Jan 24, 2013 7:12 pm

So here's the closeup of the connector and resistor inline with the black wire.

A 1.2k resistor works nicely, bumps the temperature up just enough to really make the toner stick super nice.
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videoimage.JPG

embelectro
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Re: Scotch TL901 Laminator PCB etching heat modifications

Post by embelectro » Fri Oct 25, 2013 2:10 pm

Look at this link the PCB BOARD are the same http://microlabo.blogspot.com/2013/10/d ... ation.html

embelectro
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Re: Scotch TL901 Laminator PCB etching heat modifications

Post by embelectro » Fri Oct 25, 2013 2:12 pm

Look at this link the PCB BOARD are the same http://microlabo.blogspot.com/2013/10/d ... ation.html

snappytaco
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Re: Scotch TL901 Laminator PCB etching heat modifications

Post by snappytaco » Fri Nov 01, 2013 7:54 pm

I have a few questions regarding your mod;
1) at what points on the board are you measuring voltage.
2) what is the correct voltage to equal the correct heat.
3) how to calculate the resistance value.
I tried your mod exactly on the newer model scotch laminator( the board and diode look the same) but I'm not able to raise the temp. I'm measuring the temp using a enfrared thermometer. I'm measuring an actual board copper side up with black construction paper on top. Measurements are taken after several passes or until temp is maximized.
On the 5mil setting with resistor in series with the diode I get 90-94c.
I compaired this to using an iron at max setting and I'm getting about 145c.
I really want to use the laminator because i think it provides a more even temp and pressure.
Please advise.

Best regards.

snappytaco
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Re: Scotch TL901 Laminator PCB etching heat modifications

Post by snappytaco » Fri Nov 01, 2013 8:46 pm

Where on the board are you testing voltage?
How do you calculate for resistance to achieve correct voltage/temp.

redmiata
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Re: Scotch TL901 Laminator PCB etching heat modifications

Post by redmiata » Sun Nov 10, 2013 10:49 am

I went up to about a 15k resistor with mediocre results. The board is etchable after 10 passes, but not clean. I'm still working on it, so let me know if you want my work-through.
Kudo's to the original poster for thinking of the thermal fuse value, but apparently he didn't think that they'd use a different thermistor.
I find it Interesting that his board markings and mine are identical except for the manufacturer.
I also found that once the ready light comes on, the heater only cycles on about 1/2 of the time regardless of temperature.
The motor also runs the board through pretty quick, not allowing good heat transfer and re-heating of the rollers.
Both the motor and heater are 120 vac (US) so I plan to use an Arduino/Optoisolator/Triac circuit to control them.
The Arduino will also allow a cool down cycle. Shutting off hot rubber rollers under pressure is unwise.
I'll keep you up as time permits.

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