What are the 5v regulator mod?

[7800fan]

Saw this mentioned a few times but the only detail I could find is on a non-English site with some missing picture. When I tried to translate it, I poor translation like there's too many technical words that isn't in Google's vocabulary.

 

Can someone give me an easy guide for dummies? Seems like it involves removing a few parts and a transistor that is prone to failing and replacing with a regulator but which pinout and where. And not all picture are clear if it's for Lynx 1 or 2, both used different numbering.

[leonk]

Google translate is your friend for this:

 

http://circuit-board.de/forum/index.php/Thread/4779-TUT-srdwa-Donking2000-Atari-Lynx-1-2-Spannungsregler-Umbau-SMD-Variante/?s=57e20125a860dd0b9153c2a4c85b17ebf0b8a076

 

I did this on my Lynx 2, except I used:

 

- brand new IN4001 instead of reuse the ones from D9/D11 on my Lynx 2

- used switching 7805 replacement (rather than standard 7805) - it generates no heat and a lot more reliable. It's also rated for input voltage of 7V-35V!!!

 

Unless you know how to read schematics, and done similar type mods before, I suggest you let someone else do it for you. Just my $0.02.

[7800fan]

I wanted to go with LD1117S50TR as it's smaller than most 7805 and other regulators. When I used Google translate, all the pictures and text were separated and all the text were bunched on the top, which made matching what the text with the picture hard. The poster didn't use anything like pic 1, pic 2, etc to refer to specific picture. Also Google didn't translate all the text: (no idea if it has typo or if Google didn't have these in their vocabulary)

 

rausgebrochenem

bastelter

Zinnberg

Lötkünsten

 

It's hard to tell what to remove and what to keep with jumbled up pictures.

 

What I ended up doing was to copy the whole thing to word (Open Office) and I translated only a block at a time to maintain the space between pictures. This is what I ended up (and schematic for Lynx II power supply, original one \stolen from AA member and revised based on what I can figure from that German site)

First: remove and cut (in red)

 

Then these mods:

 

Since the new regulator chip would bridge where the 2 diodes were removed, no need to add wire. But it is odd that the user on German site needed to add wire from battery + post to Vin pin of the chip when the schematic shows the battery is directly connected. Maybe the original schematic is wrong in where the + input of the battery is? Or that German version of Lynx is wired a bit different? I'll have to check the continuity on my Lynx when I take it apart to do the mod. (got 2 on hand and 2 more somewhere, planning to do another LCD mod and make it into mini arcade)

[leonk]

For my install, I picked up the following voltage regulator (while purchasing an NESRGB kit for a customer):

 

http://etim.net.au/shop/shop.php?crn=206&rn=547&action=show_detail

 

It's the OKI-78SR-5 Switching Regulator (5V). I then followed the German instructions (except I forgot to remove ZD13/I left it in place, I believe it might be needed for the small LED light in the front of the unit, oh well. All works great). In any case, I think a good switching regulator is much better than a 70's technology 7805 or 90's tech 7805 reduced to the size of surface mount. Once the mod is done, I don't like to get into the system to fix it.. EVER. (this is why I also did a full cap kit).

 

The instructions online are correct. The +VE terminal of the battery holder should touch the pad of D11 that's closest to that big cap. In this mod, it's labelled "OUT" in pics lower in the post. What this mod does is send the power from the batteries through the voltage regulator as well! (original design did not do that).

 

If you insist on using the other regulators, keep this in mind. All regulators must have 3 pins:

 

- IN - unregulated power in (from DC plug or AA batteries)

- GROUND - to drain extra voltage to

- OUT - regulated 5V power

 

In your 2nd pic, it doesn't seem you have it connected correctly. top rail in schematics is 5V. bottom rail is GND. (rail = horizontal line going across entire picture)

Edited March 17, 2015 by leonk

[7800fan]

For my install, I picked up the following voltage regulator (while purchasing an NESRGB kit for a customer):

 

http://etim.net.au/shop/shop.php?crn=206&rn=547&action=show_detail

 

It's the OKI-78SR-5 Switching Regulator (5V). I then followed the German instructions (except I forgot to remove ZD13/I left it in place, I believe it might be needed for the small LED light in the front of the unit, oh well. All works great). In any case, I think a good switching regulator is much better than a 70's technology 7805 or 90's tech 7805 reduced to the size of surface mount. Once the mod is done, I don't like to get into the system to fix it.. EVER. (this is why I also did a full cap kit).

 

The instructions online are correct. The +VE terminal of the battery holder should touch the pad of D11 that's closest to that big cap. In this mod, it's labelled "OUT" in pics lower in the post. What this mod does is send the power from the batteries through the voltage regulator as well! (original design did not do that).

 

If you insist on using the other regulators, keep this in mind. All regulators must have 3 pins:

 

- IN - unregulated power in (from DC plug or AA batteries)

- GROUND - to drain extra voltage to

- OUT - regulated 5V power

 

In your 2nd pic, it doesn't seem you have it connected correctly. top rail in schematics is 5V. bottom rail is GND. (rail = horizontal line going across entire picture)

 

The middle pin and the tab are both 5v output. The person choose to solder the tab directly to the 5v rail and break off the middle pin. The left pin is Vin and right pin is ground. On Lynx motherboard, the ground and Vin is opposite so the regulator was soldered in upside-down to match the pins.

 

I should have mentioned the tab is soldered to 5v rail in the schematic

[leonk]

Got it. So it should work fine, except you have to remember the following:

 

1) Tolerances are lower on these SMD voltage regulators

2) Heat - do they require any passive cooling (i.e. heat sink)

 

Best to find datasheet for the part you want to use and read it. Apart from that it all looks good!

[7800fan]

It's a switching regulator, not linear like 7805 and shouldn't need heatsink. Those Germans did it without heatsinking theirs.

 

I did a quick check, the + terminal of the battery is directly connected to the power rail at the cathode end of the diode so it seems odd one would need to cut the trace and then run a wire there to get power from battery to the new regulator. I checked some more, the trace also goes through inductor L17 to possibly resistor R86, and also goes to power jack. I haven't removed any part yet but the schematic may not be quite right, there are probably other changes beside part number when Atari redesigned Lynx II.

 

Looks like I may need to dig out my Lynx #5, the only one that is truly dead and start removing pieces to get better track of the circuit traces. Now where did I leave that one...?

 

Unless by chance someone finds the correct Lynx II schematic?

[leonk]

?? Please read my post above. It explains how the +ve terminal of the battery connects AFTER the diode / spot where OUT from 7805 should connect. The German mod forces the battery power to also go through the 7805 rather than after. The cut and wire IS needed if you want to regulate the 9V from the batteries.

[7800fan]

I got the parts in the mail yesterday so I took the time to do a mod one of my Lynx. It worked. I was playing Blue Lightning off AC power and I didn't notice any unusual warm up or other issue that may indicate a need for heat sink. The tiny regulator is more efficient than a more common (and cheaper) 7805 regulator but it is rather small. It's hard enough safely removing a few SMD parts without ripping up pads or traces that trying to solder in one (upside down too) needs a fair amount of patience.

 

Still 3 more to mod, 4 if I can find my dead Lynx (busted transformer) for second LCD replacement.

 

?? Please read my post above. It explains how the +ve terminal of the battery connects AFTER the diode / spot where OUT from 7805 should connect. The German mod forces the battery power to also go through the 7805 rather than after. The cut and wire IS needed if you want to regulate the 9V from the batteries.

 

Yeah my bad. I was looking at the schematic and I forgot for a moment that the battery connects *after* where the 5v regulator would be installed when one wants it *before* the regulator.

[leonk]

I have a Lynx system where the diodes just past the voltage straight through without lowering it to 5V! Wait on AC or batteries, it just shows a white screen. It only works fine when I use a 6V AC power. Perfect candidate for power regulator!

[7800fan]

The actual regulating is done further down the chain, at zener diode. It's supposed to dump excess voltage to ground while maintaining 5v across the spot. (seems like inefficient design BTW unless I misread schematic) If the diode or resistor failed, you won't get 5v regulation.

 

I'm almost afraid to ask, does your Lynx still work with 6v power? If so, you're lucky. Many component usually fries easily when you dump 9v due to failed volt regulator.

[7800fan]

Either I messed up something or the volt mod is not compatible with the LCD mod. When the Lynx is on battery, all seems OK. But when I'm using AC adapter (original Atari), the initial title screen comes up fine then the main game screen turns gibberish, LED power light dims, then it crashes and shuts off. I have already double checked for problem like loose wire, leftover bits like clipped wires or solder blobs, etc. Nothing stands out.

 

The battery does not have any diode that protects against reverse voltage (according to schematic, the one diode on -v is bypassed when power plug is not inserted) and the volt mod has only a diode on +v from power to regulator. I will need to recheck that diode.

 

I'd spend more time checking (both that suspect diode and the AC adapter, it is old and could be dying) but I spent over 4 hours recapping TG-16, adding S-Video to it, recapping one of my older Game Gear, and recapping one of non-modded Lynx to try and restore dead sound.

[7800fan]

Solved!!!

 

I checked, got 5v after the regulator but when the game started to play, the voltage dropped below 3.5 before Lynx crashed and shut off. I swapped for another LD1117S50TR, same thing. Just to rule out problem with that regulator, I inserted a plain 7805 and it worked fine.

 

Now I just need to figure out why LD1117S50TR worked fine with battery but not with DC power. The diode should have not made any difference on the input as the input voltage was still higher than minimum needed for the regulator to work. The adapter (Atari branded) measured 14.5v with no load and 8.3v when plugged in.

 

For the moment, I'll assume somehow that the small efficient regulator is somehow good enough for original LCD with power guzzling CCFL but not for new LCD. I have 2 other Lynxes with LD1117S50TR installed and still has original LCD, they are working fine.

[leonk]

FYI, I went to a big retro game swap here where I was showing off my console mods. People were amazed by backlit original Gameboy, gameboy advance, Lynx with new lcd and my new lcd sega nomad. The show was about 6 hours long. All systems worked like a champ except for 2.

 

Original gameboy got warm (running off batteries) and nomad had main pcb shut down after 2 hours!! Only lcd stayed on (had black screen). I assumed thermal shutdown because when I got home nomad was working fine again.

 

Well. It seems nomad has one of those tiny power inverters.

 

I removed it and installed my go to >90% efficiency switching modern power inverter. It's now been running for >6 hours cold!!

 

I'm a believer in modern switching power regulators. They cost more but worth it! See attached pics.

[leonk]

 

Edited March 31, 2015 by leonk

[Turbojerry]

This is what I ended up with on my 2 Lynx II's and Lynx I so far. I looked at that German site then figured out how I wanted to execute it. I found that the stock set up was allowing 9-11 volts to the chips with an offical Atari ac adapter... I'm also trying the R-785 on my 7800 since they are known to have a loose heat sink and it falls off taking the 7805 with it after some time.

[leonk]

LCD mod too!

 

Why did you leave Q8?

Edited April 2, 2015 by leonk

[Turbojerry]

I was having trouble with the LM1117. so after 2 of them causing weird stuff I reinstalled Q8 just in case I missed something, but it made no difference and is not needed. the R-785 was the answer as the 7805 was getting too hot for my liking even with a heat sink. the Lynx only pulls 350ma but the heat from the 7805 felt like it was pulling 50 amps... But yes it has McWills awesome screen also !

[leonk]

I know you're super happy with your power mod and its 1000 times better than zenor diodes. If you ever do another Lynx, try the switching voltage regulator I have shown above. You'll be pleasantly surprised by its performance.

[Turbojerry]

I have the regulator you shown in several items. My 1967 440 dodge dart instrument cluster, My top and side load nes with nesrgb, And Sega genesis model 1 (2 regulaors in that one of course). I like the R-785 because it's small and it's a 95% efficient switching regulator. I've tested it to 1 amp and it seems to like it but it's only rated for 1 amp. It fits in the portable consoles like it was made for them...

[GTretro87]

Hey all, I'm in the same dilemma.

 

I recently received two Lynx 2's from ebay. One was described not working (powers on with cart, but no sound and blank screen), and the other (which I received yesterday) was described as "mint condition...excellent, picture, sound and all around condition" "console is guaranteed 100% tested working, no missing pixels..." ----- well that one doesn't boot up at all.

 

I got it in a bundle with a Nakitek power supply (6v to 9v switch - to me, I rather have a Lynx PSU), and that's the first way I tried to boot it up - no go at 6v, tried 9v, still no go. tried batteries, STILL no go... So I'm suspecting a Q12 (which I've ordered spares from Console5), and I also ordered R785.0-1.0 switching regulators. I also have a set of replacement capacitors just to freshen them up.

 

 

What do you guys think it needs? Or what procedure I should follow to get these back up and running instead of blowing more money towards another Lynx :\

 

I haven't opened them up yet to see which board revision they are but I will tonight - because I want to play my Lynx already! - I've checked out all the possible links towards repairing these lynx's - like the soft power mod, this 5v regulator mod (the german site, and greek too I found)..

 

Please help me out guys

[GTretro87]

Turbojerry, did you also scratch away at the battery + trace and wired it up so that power goes to the regulator first and then the rest of the board?

 

Do you guys think that with a simple removal of D9 and D11, and replacing them with a single regulator is worth it than cutting any traces? Like a straight drop in?

[StijnDW]

As a first quick test,

Find yourself a stable 5v 1 amp power supply. I use an old

switching power supply from an external hard drive.

Connect it across C41 with some temporary wires soldered to it. Don't mix up the polarity.

Fire up the power supply. If the lynx works there's a problem with the power regulation circuit. If not then something else is wrong.

[Mojado]

I wanted to go with LD1117S50TR as it's smaller than most 7805 and other regulators. When I used Google translate, all the pictures and text were separated and all the text were bunched on the top, which made matching what the text with the picture hard. The poster didn't use anything like pic 1, pic 2, etc to refer to specific picture. Also Google didn't translate all the text: (no idea if it has typo or if Google didn't have these in their vocabulary)

 

rausgebrochenem

bastelter

Zinnberg

Lötkünsten

 

It's hard to tell what to remove and what to keep with jumbled up pictures.

 

What I ended up doing was to copy the whole thing to word (Open Office) and I translated only a block at a time to maintain the space between pictures. This is what I ended up (and schematic for Lynx II power supply, original one \stolen from AA member and revised based on what I can figure from that German site)

First: remove and cut (in red)

 

Then these mods:

 

Since the new regulator chip would bridge where the 2 diodes were removed, no need to add wire. But it is odd that the user on German site needed to add wire from battery + post to Vin pin of the chip when the schematic shows the battery is directly connected. Maybe the original schematic is wrong in where the + input of the battery is? Or that German version of Lynx is wired a bit different? I'll have to check the continuity on my Lynx when I take it apart to do the mod. (got 2 on hand and 2 more somewhere, planning to do another LCD mod and make it into mini arcade)

Noob here. I have a couple of questions that I haven't found the answer to.

 

1st, why do people do this mod? Does the current 5V regulation setup tend to fail?

 

2nd, why is D18 (D9 on Lynx II) removed? Looks like its a free-wheeling diode (for negative voltage suppression) to protect against unplugged ac power or if you pull the batteries while the unit is on, etc. I don't see why one would want to remove transient suppression to do this mod.

 

Edit: 3rd question, moving D11 to the left of the AC connected voltage-divider resistors makes the Lynx think its on AC power when it's really on batteries. Why is this done that way?

Edited May 29, 2016 by Mojado

[cowdog360]

Those are actually really good questions. I just wrote up a how-to for people who wanted to do it. However, the last few Lynx's I've stopped doing the regulator mod on, and just replace the D13 zener with a newer one just for reliability.

 

The main issue is that when the zener goes, the regulation fails and then you get 9V into the rest of the Lynx. So the modern 5V regulator is something people are doing for safety. What I've seen though with the way this mod is done is that the DC-DC converters draw power even when off, so the batteries drain out pretty quick compared to the original circuitry.

 

Ideally, I'd just keep the original circuitry and the best thing to do would be to develop a crowbar circuit to catch things if the voltage pops over 5V.

 

I'll have to sit down and really look at the circuit to answer the other questions you have.