Update 7805 to OKI-78SR-5 for heat reduction

[Keith Courage]

Well, I wasn't referring to leaking caps obviously. Leaking caps can damage other things. I have yet to see any  damage of any kind caused by the original 7805s. If they no longer work then of course you should change them but if they work I see no point.

[thesteve]

im not saying not to do it, just that the heat isnt the only consideration
a micro switcher will have a coil, diode and caps on board along with a pulse generator
the caps are likely driven to their limits as space constraints were a major consideration in the device and can fail
now in a TE i would highly recommend using something like this as it will extend battery life
35V max input is the same as the 7805

[SmokeMonster]

I didn't remember seeing a 7805 in the TE, does it use them as well? Extra battery life would be nice.

Isn't there an issue with the sound caps on the Duo getting heat stressed because of their proximity to the two 7805s?

[CkRtech]

Well, I wasn't referring to leaking caps obviously. Leaking caps can damage other things. I have yet to see any  damage of any kind caused by the original 7805s. If they no longer work then of course you should change them but if they work I see no point.

Heat. The point is to eliminate (reduce) heat output. Heat is not really good for electronics, and you have two voltage regulators right at the sound circuit. Those 7805s are terrible as they are extremely inefficient and produce a ridiculous amount of heat. You could remove them both along with their heatsinks and seriously reduce just how hot the area gets during operation. Replace the caps is still an obvious part of Duo longevity, and I honestly think replacing the voltage regulators should be as well - despite the fact I haven't done it yet on mine.

I am rather shocked that you guys would oppose this, honestly. To me, it is a "duh. You obviously should do this" operation, and I am also shocked people haven't done it already. It is quite cheap and eliminates heat. Win-win

[RGB32e]

That said, the negative feedback from thesteve and Keith makes me less enthusiastic about doing this to NEC consoles.

 
I wouldn't be concerned with their comments.  The Turbo Duo systems generate a fair amount of heat with the two stock 7805s.  Try leaving your finger on one of the heat sinks for a minute after the console has been on for a while!

Even Tim Worthington sells switching DC/DC converters on his site.  They are modern drop-in replacements for the old 7805s.  He has been incorporating switching DC/DC in a number of his products such as the Famicom-PA board and soon to be released 2600RGB.  Not to mention that a switching DC/DC converter will be a requirement for the HiDefNES.

I think Tim's ability to create a competent component video circuit  , as well as his other spectacular products (AV-DRIVER ) and adoption of switching DC/DC converters in his designs trumps a few bits of conjecture.  Also, if you're not using one of his AV-DRIVERs for RGB modding a Hu6260 based system, you're doing it wrong. 

[SignOfZeta]

My PCEs (and all the other things I have that run on similar gear) have run for DECADES on these supposedly inferior parts. If there was a problem, doesn't it seem like there would have been a symptom? When will I see eventual failure? After my (now 26 year old) briefcase is 30 years old? 40 years old? Will I even be alive when this shit finally breaks?

And no, it's not analogous to failed caps. Failed caps...are *failed* caps. Having one of these regulators crap out as about as common as having a black Duo that's still operating with all its original semiconductors.

Also, heat is not fundamentally bad for electronics. Without heat they wouldn't even function. Only *excessive* heat is problematic, and just because the surface of the case is slightly warmer to the touch...that's not necessarily a problem. It's just life the universe and everything doing its thing.

The black Duos certainly aren't failing caps near the audio stage because of heat. Those are simply the first to go (probably because the electrolyte runs out quicker when it's warmer). All the caps on those machines were bad.

I'm not saying to not replace them if you want, knock yourself out, but you're not going to make me feel like a negligent fool for not de-soldering stuff off a virgin mainboard older than half the noobs on this forum based on a flawed semi-informed axiom.

[ProfessorProfessorson]

I love the old trusty 7805. Got no intention of swapping it out unless one goes bad. Fact is the Duo caps near them would have gone bad anyway eventually regardless of heat generated from the 7805, because I mean its pretty normal for caps to go bad from use after like 17-20 years. If you have anything still running strong with no issue, on multiple original electrolytic caps after heavy use for that long, count yourself lucky. I have even been coming across random dry caps in Genesis model 1 decks the past few years. Was a totally common problem on arcade boards I would purchase. Caps that were nowhere near the volt regulators. Shit just happens.

[ApolloBoy]

I've experimented with those switching regulators before, they're neat but the problem with some of them is that they tend to emit some noticeable interference. You can bring down the interference by using an inductor though.

[SignOfZeta]

If there is anything the PCE could use less of, it's noise. I was half expecting someone to say these new regs would reduce noise, that would actually be worth it. If they make the sound chip squeal even more, not interested.

[SmokeMonster]

It must depend on the application and the regulator type, because in my Genesis and SNES/SFC it is the exact same AV quality with no added noise at all (via Scart RGB at least).

Mine aren't stock though, as I've pulled the RF box from all them and they're recapped with high quality caps. Any modicum of signal noise is very apparent in my setups (GBS-8200 and an LKV362A) and I compared the modded SNES to the unmodded SFC for a few weeks before going ahead and doing it too.

I have absolutely no idea how they fare in a TG16 or Duo though.

[MNKyDeth]

Bringing this thread back.... cough....

Has anyone tested these in a Duo yet?

Basically I am about to order some for my Genesis this week as I am recapping that machine now. Do these have any adverse effects on the Duo?

From what I gathered from the discussion here is that they should be fine with the possibility of adding noise but even that could just be a one off event.

Also, I assume if I switch to these in my console I can still use the original power supply "Wall Wart" without any issues?

[SignOfZeta]

UPDATE: All my shit is still running.

[ProfessorProfessorson]

Yeah same update for me, anything with a 7805 in it is still working fine.

[NightWolve]

That said, the negative feedback from thesteve and Keith makes me less enthusiastic about doing this to NEC consoles.

I wouldn't be concerned with their comments.  The Turbo Duo systems generate a fair amount of heat with the two stock 7805s.  Try leaving your finger on one of the heat sinks for a minute after the console has been on for a while!

...

I think Tim's ability to create a competent component video circuit  , as well as his other spectacular products (AV-DRIVER ) and adoption of switching DC/DC converters in his designs trumps a few bits of conjecture.  Also, if you're not using one of his AV-DRIVERs for RGB modding a Hu6260 based system, you're doing it wrong. 

As Steve is an actual trained electrical engineer unlike most here commenting, his point is worth considering and looking into more before rushing in. He also designed a transistor-based YPbPr/Component circuit  released free for us fans to build ourselves unlike most others which hide the design and only sell the final product to the public, not to mention he fixes NEC consoles all day long no matter the problem. I wouldn't dismiss his opinion as mere conjecture. He's certainly got more credibility than you as someone who's been here for years versus a one-time poster that came and went...

[SignOfZeta]

I know not much at all about electronics, but it's not conjecture to say "my shit is decades old and still works". It's just a plain fact, so plain it's hard to ignore.