Sega SC-3000 voltage question

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Sega SC-3000 voltage question

Postby blahjedi on Wed Feb 24, 2016 9:22 pm

Hi there!

Chasing some help to try and sort out what's going on with my Sega SC-3000 I picked up a short while back. Long story short: Picked it (plus an Atari 2600) up in a trade for a yellowed C64c. Had no PSU/games, but powers on to the green/black screen + low pitched hum. Skip forward a couple of months and I managed to acquire a bunch of games for it (5 to be precise). They were known working, but when I tried them all the SC-3000 continued to show the green/black screen + hum.

So far I've:
  • cleaned the cartridges with cotton buds & isopropyl. repeatedly
  • Cleaned the cartridge slot using a credit cart wrapped with cleaning cloth and drowned in isoproyl (in/out motions only. no side to side!). Repeated this several times until the cloth was coming up clean!
  • Pulled the board out and confirmed that all of the cartridge slot pins are making connection with the mainboard (including the pin that's missing half of it - 8th in from top right)
  • Checked for any lifted traces or dodgy solder, but all looks a-ok. Ditto for the fuse!

I've also checked voltages off the regulator, cartridge slot & VRAM -
  • The Voltage regulator is giving me +4.6v
  • Both of the +5v points in the cartridge slot are at +4.4v
  • The VRAM is showing +4.4v

Based on this, are the voltages a bit too low to power games, or are these within ok limits for the SC3000? any other suggestions of what I could do to get this bad boy back up and running?

Thanks!!
blahjedi
 
Posts: 2
Joined: Wed Feb 24, 2016 12:14 pm

Re: Sega SC-3000 voltage question

Postby glc on Wed Feb 24, 2016 9:57 pm

Check your power supply voltages for some AC component (ie ripple) there should be none.
if there is any ripple, change the electrolytic capacitors in the power supply.
if there is no ripple, change the electrolytic capacitors in the power supply
Last edited by glc on Thu Feb 25, 2016 5:05 am, edited 1 time in total.
glc
 
Posts: 26
Joined: Tue Nov 25, 2014 5:00 am

Re: Sega SC-3000 voltage question

Postby blahjedi on Wed Feb 24, 2016 10:36 pm

Bugger, I don't have an oscilloscope here to try that with, just stuck with my basic multimeter.

With that said, I've tried using 3 different 9v/1amp Master System PSUs with the machine, but all with the same outcome sadly.
blahjedi
 
Posts: 2
Joined: Wed Feb 24, 2016 12:14 pm


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