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Hello all,

I apologize, this may be a bit long, but I want to be thorough.

I recently finished my first DMG CPU-06 overhaul including capacitor replacements, backlight (HHLv3 built in resistors), 'bivert' module (HHL v2), pro sound (post pot), and supplemental Polulo S7V7F5 step-up/step-down regulator for the rest of the system. The stock DC CONV DMG (version with single 33uf25V cap) is supplying LCD and backlight power only.

I'd read in several places that older power boards such as the one in my model have poorer efficiency than the later CPU-08 versions (that include DC CONV2 DMG) so they can't take additional load such as a backlight and/or flash cartridge without straining themselves to the point of mechanical failure.

This set me out on a search for an aftermarket power solution. I've seen a thread here and a few others elsewhere that people were starting to design an alternative power board but none have come to fruition that I can find (except one, see bottom *). Then I saw some comments from BennVenn on a post or two where people wanted to replace the power board with just a Polulo. He mentioned the stock power supply needs something on the 5V rail in order to supply the negative LCD voltage, one of his suggestions being a backlight. So this led to setting up my old DC CONV DMG power board with the lighter duty of powering only the backlight and LCD letting the Polulo supply the rest to the system. My understanding is that the DMG uses ~150mA under load (depending on cartridge) and that backlights may use ~10-40mA so this should give plenty of headroom for the old power board.

It's been a joy to use so far and I've done a few sessions in LSDJ. But, I noticed when it's been on for 30 minutes to two hours recording audio that the lower left corner is 'slightly' warm. Not hot, but not cold either. Only after an hour or two the batteries (Alkaline, non rechargeable) are in a similar state, not hot, but not cold. 

So this is where I'm concerned- I have the stock DC CONV DMG with a backlight drawing a supposed ~40mA on the 5V rail direct to its + tab with built in resistors and supplying the negative voltage to the LCD panel. Ground is connected from power board to CPU board as well. I would think, if anything, the DC CONV DMG board would be less strained and less likely to heat up but this doesn't seem to be the case.

This might be barking up the wrong tree but I had the thought that since the negative from the LCD runs through the DC CONV DMG it may have to do with the 'bivert' module install. Then again I'm probably wrong on this and it's handled by the Polulo instead. But to potentially rule it out I've double checked that there was continuity between the connections that should have it and made sure there weren't any shorts. I've read some about it but have very little understanding on floating inputs, mostly that they should be connected to VCC or ground if not used. The module's product page states 'Grounding for the remaining pins for increased reliability' and it uses the 74HC04D hex inverter so I wouldn't think that to be a cause but not sure how to test if it might be a lemon either.

I feel like I've checked the replaced capacitor values and orientations at least three times now so I don't think there's anything there...

I've written all this, and done a ton of reading, and the thought occurs to me that maybe that's just how the old power boards are- they all give off the slightest amount of heat that doesn't have anywhere to go so it just accumulates in that corner. I don't know, I set out to put together a DMG that hopefully would last me for years and can't escape the feeling something might not have been done right or I'm missing something.

Given this I'd appreciate anyone's input on what I could check or if I'm just overly concerned about my console. Thanks for reading and for being such a valuable resource through the whole process!


* The power board mentioned earlier is called a "CleanPower Regulator" board made by RetroSix in the UK that HHL has started stocking as well. Screenshots show it's a 6V rail instead of 5V so I wanted to wait until it's been out for a while to see other people's thoughts on it.

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NUMBSKULL

Have you seen this? https://retrosix.co.uk/CleanPower-Regul … p141361110

Full disclosure: I did not read your post

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Yes, thank you for replying, I have. I had considered it initially but it looks like it provides 6v instead of 5v and possibly a higher negative voltage value for the LCD based on an earlier version in the screenshots. I don't know how giving 6v to 5v logic would work in the long run and the same for the negative voltage for the LCD. I’m ignorant when it comes to this but anything I searched for when feeding higher volts to a lower rated line wasn’t always a good practice in general. For the DMG specifically I couldn't find anything more about it..

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NUMBSKULL

As far as I know, lower (higher) negative voltage will result in a higher contrast screen.

The other option is to get one of the new IPS lcd kits and then eliminate the built in regulator completely and just use your 5v regulator. Haven't tried that myself yet but I heard that it works fine.

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Oh thats pretty neat- I didn't realize the new IPS displays don't require the old power boards at all. I plan to mod another DMG at some point in the future and may give that route a go.

For this current one I’m trying to keep it as close to stock ‘feeling’ as possible, if that makes sense. Picked a backlight close to the pea soup color as well. If possible I’d like to keep the original LCD and shell for this one in tact.

Thanks again for the suggestions and responses!

Last edited by Split (Apr 8, 2020 9:15 pm)

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Philadelphia

I HIGHLY recommend the IPS mod. Did it myself a few months ago and it's so crisp. And the upside is you can adjust the color and brightness of the screen to conserve battery power. Assuming you're using it for making music, I've found that the darker colors (red and blue, primarily) cause less background noise.

Last edited by Doctor Octoroc (Apr 9, 2020 11:45 pm)

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That does look really clean- the one I just did is for more all purpose, games, music, software. The next one I was considering piecing together more for music with a capacitor swap for the lower frequencies and darker color combos, maybe blackout. That's super interesting to learn about the noise intereference based on palletes, thanks!

Last edited by Split (Apr 10, 2020 3:32 am)

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Ok who's selling IPS modded WITH prosound and the new powerboard (and maybe the audio recap?) Im seeing mostly gamer-focused stores.

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NUMBSKULL
herr_prof wrote:

Ok who's selling IPS modded WITH prosound and the new powerboard (and maybe the audio recap?) Im seeing mostly gamer-focused stores.

Something like that would probably cost in the $200 range. Is that something you'd be willing to pay for?

Cheaper is to just take your already modded dmg and replace the screen. The IPS is a complete drop in replacement so it's pretty easy.

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Philadelphia

So I still stand by the IPS screen mod but I'm having an issue and maybe someone with a bit more experience can help.

Turned on my DMG with IPS and prosund mod earlier today and got the normal "Gameboy" splash screen and ding but then the screen went black (not off, just no graphics displayed). Turned it off and on again and the screen illuminates, sound appears to be working (that initial 'bump' sound can be heard but nothing after that) but no splash or display. Tried taking the MGB cart out and turning it on without any cart inside, nothing . Tried a few other game carts, no change.

From what I can tell, everything works except for perhaps the connection somewhere between the old board and the new one that came with the IPS mod. I don't think the IPS itself is the problem but I did notice that when it first goes on, it appears brighter then dims to the normal brightness (for an all black screen). It's an odd problem because both the screen and sound work but neither is being produced.

I checked the ribbon cable and the connection is solid. Removed the main cable (between front and back board) and turned on with no screen (as expected) or indication of sound - plugged it back in, same as before with the 'bump' and illuminated screen but no display. I'm baffled.

Last edited by Doctor Octoroc (May 27, 2020 7:59 am)

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Philadelphia

So quick update, I tried turning it on today and turning the color/brightness wheel to see if there was any response and it was too tight (screws were a tad overturned) so I went to loosen them up and once I released some pressure from the two screws closest to the wheel, the display came on for a few seconds. I got all excited but then I lost it again and can't get it back no matter what I do.

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Sea of Souls
Doctor Octoroc wrote:

So quick update, I tried turning it on today and turning the color/brightness wheel to see if there was any response and it was too tight (screws were a tad overturned) so I went to loosen them up and once I released some pressure from the two screws closest to the wheel, the display came on for a few seconds. I got all excited but then I lost it again and can't get it back no matter what I do.

It sounds like there may be a broken solder joint on the wheel, or near it. Can you look at the solder points very closely? Both on the wheel and the other component on the opposite side of the board?

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Philadelphia
Orgia Mode wrote:
Doctor Octoroc wrote:

So quick update, I tried turning it on today and turning the color/brightness wheel to see if there was any response and it was too tight (screws were a tad overturned) so I went to loosen them up and once I released some pressure from the two screws closest to the wheel, the display came on for a few seconds. I got all excited but then I lost it again and can't get it back no matter what I do.

It sounds like there may be a broken solder joint on the wheel, or near it. Can you look at the solder points very closely? Both on the wheel and the other component on the opposite side of the board?

I took it apart yesterday and looked all all the caps and joints and didn't spot anything out of the ordinary but that sounds like the most likely culprit since it managed to come back briefly. The easiest fix may honestly just be replacing the main board and redoing the pro sound mod, if I can't locate the precise point of failure. For all I know, it could be one of the pins connecting the cart connector to the main board which I don't think is an easy fix.