Vector Arcade Machine - Pre Flight Checks

[RolyRetro]

I've been working through the checks on the power brick of my Star Wars arcade, all passed ok, now moving onto the AR2.

I don't have the sense mod fitted, but is the testing process the same? It wasn't 100% clear from the post and I want to be sure before testing any further.

Cheers

Alex

 

[ColinD]

You need the sense mod fitted to be able to check the 5v correctly without anything plugged in to the AR2 output as otherwise the regulator has no feeback and will wind the output up.

I have used 6v lamps or two 3v in series to provide a bit of a load in the past but its not that essential.
ColinD2016-06-12 19:44:50

 

[Nes4life]

I just sense modded 2 AR boards this evening and have ordered a 5W 10Ohm axial resistor to give it a load.
Been watching RGP's YouTube videos on it all; top stuff.

 

[Stickman]

Excellent thread but I have an issue I cannot get to the bottom of. Sense mod has been done on the AR and all voltages on power brick and AR are fine but one. The -5v measured on pins 9 and 12 is -14v. I have checked everything in the circuit component wise replaced the caps and also the transistor. Measured the resistors and they all ok.

I am getting 38v ac onto the board (36v shown on schematics) and have followed the schematics. I am at loss on this. I can’t believe it is that high as it has no load. And on here the tests were -7v. Stickman2020-02-01 17:57:21

 

[andyman]

-5v comes directly from the 7905 regulator at Q9...check voltage going in...should be around 20 ish, if it is, bad regulator...

 

[Stickman]

I looked at Q9 and actually replaced it as well, I got this Star Wars about 12 months ago, being restoring it and have now got to the point of rebuilding, the AR looks like it has already been rebuilt and I got a rebuild kit thrown in with it.

I am seeing about -25 volts across R31

 

[andyman]

Until it gets to R31 its unregulated DC (hope you mean 25VDC) so thats not off by much although on the max input...are you sure you put in a 7905 and not a 7915 by mistake...if yes, then you could have a dodgy reg still

andyman2020-02-01 18:48:26

 

[Stickman]

pretty sure it was a 7905 yes it was 25v dc, each side of r31 and gnd. I am going to go and look at it again right now

Yep defo a 7905, done a bit of reading up on it so understand what it is doing now. I have another one so will swap out in the morning and see what happens
Stickman2020-02-01 19:26:14

 

[Stickman]

ok popped in another new 7905 from a rebuild kit I had laying around. Still get -13v out. Input in -24v that’s three 7905’s that all give the same out.

Surely I have not got three bad ones!

 

[andyman]

I wouldnt say so...not beyond the realms of possibility though...

Are you testing these voltages under load ??

 

[smarty]

I expect it'll measure correctly under load.

I had some that spat out -15 unloaded a few years back. Bob Roberts has a page on his website about it:

http://www.therealbobroberts.net/7905.html

smarty2020-02-02 12:42:39

 

[Stickman]

I took the gamble and put the board in, it pulls down to -5.02

.

So now I have to get on with the 6100, spot killer and no HV. Time to search the forums.

Thanks for the input guys