killedatschool
Offline
Baton Rouge, LA

So I have two dmgs with overheating regulator boards. One has a backlight and rca prosound and only gets hot when I use it with arduinoboy. The other has a backlight, rca prosound and 1/4 prosound therefore I had to move regulator board. That one gets hot just playing it by itself. I have done tons of googling and searching and it seems that adding a resistor can possibly solve these problems. I’ve seen so many different values of resistors recommended and with my lack of knowledge on resistors it’s made it rather confusing. I ordered 30ohm from Amazon. I’m hoping that will be enough. Is there anything else I need to know about the resistor?

Also I believe these backlights have resistors built in. Shouldn’t this have prevented the overload?
I would really appreciate some advice. I’ve posted in other threads but they just get lost in the heap and I haven’t gotten a response 

Thnx.

killedatschool
Offline
Baton Rouge, LA

Bump

urbster1
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Naptown

you definitely need a resistor for the backlight. but that may or may not help your overheating problem. resistor should be 100ohm, more than that will probably dim it too much but YMMV. you can also try using a 1k ohm trimpot and set it to the brightness you prefer.
if you want to fix the overheating i would suggest installing an extra power regulator to power the backlight, following instructions in this post

Last edited by urbster1 (Mar 19, 2018 6:47 pm)

killedatschool
Offline
Baton Rouge, LA

First of all thank you for responding. The mod you suggested looks very simple I will definitely give this a go.

As far as the 100ohm resistor. Does this still apply if the backlight has built in resistors?

urbster1
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Naptown

do you know where you got the backlight or was it provided to you without any information? i've heard that some HHL backlights have built-in resistors, but the ones i have came with resistors (i.e. included in the package), but not directly in the backlight itself. in any case, adding more resistance just means your backlight will be dimmer, but like i said you can always just use a trimpot and adjust brightness to your liking (i would recommend keeping it in the case, i've modded one to be accessible from outside the case but imho it wasn't worth the trouble as i rarely adjusted the brightness)

Last edited by urbster1 (Mar 19, 2018 7:52 pm)

killedatschool
Offline
Baton Rouge, LA

It’s a yellow backlight from ASMRetro. I got it a couple years ago with a bunch of other stuff. It’s been sitting in a drawer until I had project that needed it. I can’t remember what version it was but I remember it said it has built in resistors. I do have a GBMUK backlight with built in resistors and I can actually see the resistors on the little tab at the bottom. The ASM backlight does not have any visible resistors nor did it come with one separately.

urbster1
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Naptown

from a cursory google search it seems like most of the ASMRetro backlights do have built-in resistors

Apeshit
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All the ASM backlights have built in resistors.

How is your arduinoboy powered? If it's powered by the link port, then that's the extra power draw that is causing the trouble.

What I'd recommend is simply connecting to the battery power source on your front PCB. This will completely bypass the regulator and not cause any excess draw. Basically you're going to want to solder to the connection to the red power LED for this. I would recommend adding your 30 ohm resistor if you go ahead with this method.

killedatschool
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Baton Rouge, LA

Thanks Apeshit. Yes the Arduinoboy is powered by link port. I was thinking about doing this. I don’t tap directly to LED though but instead to its resistor by the lcd frame?

Now for the one with yellow backlight. It overheats ( gets pretty warm but not hot ) just by running lsdj. I am using an EMS cart and I understand it can cause power draw. I’ll try it with a derp cart when I get my paws on it. It was a gift for someone so I don’t have it with me. He says he played for an hour or so on batteries and said it gets warm but doesn’t get hot. No other problems. He’s content but I am not. Especially because I did the mod.

Apeshit
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killedatschool wrote:

I don’t tap directly to LED though but instead to its resistor by the lcd frame?

Exactly. Tap in before that resistor at the top.

killedatschool wrote:

Now for the one with yellow backlight. It overheats ( gets pretty warm but not hot ) just by running lsdj. I am using an EMS cart and I understand it can cause power draw.

Sounds like the same issue. EMS carts draw a fair bit of extra power. At this point I think backlights should be connected to the battery source as standard practice.

killedatschool
Offline
Baton Rouge, LA
Apeshit wrote:

Sounds like the same issue. EMS carts draw a fair bit of extra power. At this point I think backlights should be connected to the battery source as standard practice.

Or the secondary regulator board like urbster suggested. I have had several issues with them from doing 1/4 prosound. Starting to think they aren’t worth it.

Should I keep the ground at the capacitor under lcd or ground to battery?

Thanks you guys. I’ll update when and if this works out.

Apeshit
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killedatschool wrote:

Or the secondary regulator board like urbster suggested.

Yes. Add a second regulator and connect it to the LED source. It's not necessarily needed, though. People connected backlights to the battery power source for years without complaints.

Last edited by Apeshit (Mar 20, 2018 12:20 am)