Re: Sega G-80 PSU - Audio Amp

Well if you could build a new replacement power supply board that would fit
 in the original power supply housing and still look original then that
would be cool. Looking forward to see what you come up with.
 
 
In a message dated 3/4/2011 2:06:00 A.M. Eastern Standard Time,
zittware@hotmail.com writes:

 
Fair enough – there is something to be said for original.
As an example; my board is showing signs of over use. The Diodes (– I
assume are for the 5v/4A circuit... ) are already turning the board brown.
Yes, I can replace them and keep them high off the board to improve
airflow due to convention; but this really just a bandaid for a much larger
problem.
 
At least on my machine; I’m seeing over 4.6A of current nominally on the
5V line – as measured across the R25 sense resistor. Not sure if it’s aging
components or normal for this game.
The other item of concern is the sheer number of caps on the board;
likely stemming from the use of half wave rectifier ckts for the main supplies.
 
Additionally; I really hate the fact that they didn’t silkscreen that
board. Not having the components labels makes for a nightmare in
troubleshooting.
 
Finally; Because I want to.
 
 
 
 
From: _SVerlander@aol.com_ (mailto:SVerlander@aol.com)
Sent: Friday, March 04, 2011 12:54 AM
To: _vectorlist@vectorlist.org_ (mailto:vectorlist@vectorlist.org)
Subject: Re: VECTOR: Sega G-80 PSU - Audio Amp

 
 
I never under stood why people think a switcher is better than a linear
power supply.
I guess I just like to keep a classic original and not hack up the wiring
harness. I have 3 star trek games and have never had a problem from the
power supply's. I have seen a few that had problems with the inline pins having
bad contacts and burning up but just replace the pins and plugs and their
good as new.
It can and has been done so good luck.
 
 
In a message dated 3/4/2011 1:29:25 A.M. Eastern Standard Time,
zittware@hotmail.com writes:

 
All,
I’m about 1/2 the way through my modernizing of the G-80 PSU board in the
Sega Vector machines.
I’ve already designed and laid out the 5V/4A and 12V/3A Switcher; I’m now
going to focus on the negative voltages and soon the audio amplifier.
I believe the 5V and 12V switchers have a lot more head room than quoted
above – but I need to do some bench top testing once I have a PCB back from
batchpcb.
 
My desire is to replaced the discreet transistor amp w/ a more modern
monolithic IC – proally from Maxim.
Anyone have any clue what the specs on the transistor amp are? Wattage?

The plan is to “donate” the PSU design to the community under the open
hardware TAPR license once it’s validated and functional.
John

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Received on Fri Mar 4 02:13:44 2011