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.
