Sega Mega Drive / Genesis OEM PSUs - capacitor failures

[MtothaJ]

TL;DR - check the capacitor in your Sega Mega Drive / Genesis OEM PSU - most likely its failed and leaking electrolytic fluid.

I was having a bit of a problem with my Mega Drive 2 + Mega CD 2 combo unit - was getting quite a bit of interference / ripple in the picture - looked like AC ripple was leaking in to the DC voltage. The caps were fine in both systems so had a look at the PSUs - they have some sort of security screw but a SNES gamebit screwdriver works fine to open them up.

PSU 1



PSU 2



PSU 3 - this one is from my other MD - a HDG Model 1 - seeing the pattern decided to pop this one open as well



Some observations:
- failed caps on all three PSUs (no sh*t ), tops still flat but leaking fluid from the bottom
- crappy 'no real brand' caps used in all PSUs vs Rubycon caps used on the hardware
- 85C rated caps used

Just ordered some Panasonic low ESR 3300uF 16V 105C rated caps to replace.

 

[greedostick]

screw all that. Just buy a Sega Trio PSU from www.Retrogamecave.com

 

[MtothaJ]

The're pretty expensive and from what I can see shipping is US + Canada only at this time.
Do you have any pics of the Trio internals?

 

[RAZO]

I still love my original Genny psu's. Use them for my Super Sd, Genny, Famicom, SFC, even some newer Neo Aes consoles I have. Just dont care for these flimsy over priced after market psus.

 

[ChuChu Flamingo]

The trio is good but if you have og power supplies not much merit to upgrade. These bricks barely use any watts. Replacing the one capacitor if leaking or blown is super easy and cheap.

Only reason to upgrade to a trio is if you don't have any psu at all or to maybe feel slightly safer about your giant daisy electrical fire death trap psus.

Edit: opened mine up and it has stuff on the bottom of the capacitor. Might be glue but I doubt it. The black capacitor appearance is a little iffy too. I will order some capacitors.

 

[sparksterz]

Thanks for the PSA. I have a few sitting around and just pulled them after setting up my Mega SG

 

[MtothaJ]

Caps arrived today so replaced the caps in the 3 PSUs:



Happy to report that the ripple / interference is now gone.

As for the Trio I see little point now that the caps have been replaced. That and its a switching PSU while the OG ones are linear / coil ones.

As for the caps - the stock garbage ones are 2.5cm in height. The replacement Panasonic ones I ordered are 3.5cm - that height is still entirely fine - PSU cover closes fine on all 3 PSU's without the top making any contact with the shell - but that is as high as you can go, if e.g. you want to upgrade the caps to 25V ones instead of the standard 16V choose ones which are bigger in diameter rather than higher as you will have clearance issues.

 

[MtothaJ]

Edit: opened mine up and it has stuff on the bottom of the capacitor. Might be glue but I doubt it. The black capacitor appearance is a little iffy too. I will order some capacitors.

Its definitely the electrolytic fluid leaking. Its kind of weird that these caps vent from the bottom and not from the top but whatever - at least the soldering / desoldering and replacement is extremely easy to do so at least that's a plus.

 

[wuemura]

Electrolytic capacitors has a short life span, around 2 years if you don't use them (including shelf life) or 10 years (15 years max) in use, to avoid further problems they all must be replaced, the sooner the better. If you are gonna do a recap, it is better to use solid polymer types instead, I've posted some details here.

If you don't want to have any problems with your old consoles avoid the use of any modern switching power supply on them. SPS's uses a "special" type of electrolytic capacitors with low internal resistance or low ESR.

Old electronic consoles uses standard type capacitors, the switching from the SPS plus the medium/high ESR causes the capacitors to heat up (ohms law), to build up a pressure inside and they will fail or leak eventually.

To use a SPS on a old console all people has to do is to recap the board with low ESR caps or replace them with dry polymer type capacitors.

 

[dragonpt]

Thanks for the hint...

I guess I must check my MD1/MD2/nomad PSU's...
...

 

[MKL]

That's just glue to hold the cap in place.