WTF is wrong with my 720 (Really Pissed Off)

[Mikebetz42]

BTW...... Not sure if this was mentioned....

Try re-seating the chips on the board(s) if the power is ok. I had a re-set issue on Champ Sprint, first thought it was bad power, but the power was fine... this did the trick.

Had a sound issue on Satan's Hollow... Same fix....

Just a thought.

-Mike

 

[local413]

Reseating

Reseating the chips can be a good idea, but if you have never done it before you should try doing it on a cheap pcb.. As it's not rocket science but you can bend the legs on a chip VERY easily... Also you can break the fragile legs, crack the chips, etc.. Isn't a majority of atari chips soldered on anyway?

Try pushing down on the socketed chips first.. If you do decide to pop them out, make sure you put them back in exactly the way they came out.. As back in my newbie days I fried a bunch of joust roms by instaling them upside-down Heh, did the same thing with some Williams ram too.. There are plenty of tutorials online on how to take socked chips out. I bought a $2 chip puller that works well.. Hell, you can use a small flathead screwdriver too..

 

[kb0jjn]

you set it at 20V DC

you can test it at your power supply by touching the red probe to the +5 terminal, and the Black probe to the Ground Terminal

you should also test it at the pcb. which means you touch one of the +5 pins on the edge connector and one of the ground pins. with the jamma harness plugged in there's still enough space to touch the pins with your probes

I'm not sure what the +5 should be set at for this game. Maybe somebody else can tell you that.

Don't worry too much about the Black lead. I usually "plant" the lead on a ground somewhere close to where I will be probing around. This way you only have one lead to hold on to and look at meter. Just about any ground will do but try to use one on the power supply. Sometimes I will add a wire just for the meter ground. something like an aligator clip attached to - of the power supply. Once the black lead is on a ground source, you just use the red lead to the supply voltage (in this case) and you can probe the +5 +12 with just the red lead. The meter will show the voltages that are present.

This info is just for testing the voltages...Do NOT use the ohm setting to measure voltages. You WILL do damage to the meter. You can use the ohm settings for checking buttons and fuses (when powered off). Also don't switch the meter settings while ANY meter lead is connected to anything.

I would not probe the chips at this point as you can short a chip really easy. You can test voltages on the caps with less chance of shorting something.

 

[Clytor]

If the garbage appeared after you swapped joysticks, it might be something simple. One guess is that the the pcbs or power connector got jostled when you swapped joyticks. Those power connectors at the bottom of the pcb set can get rather oxidized. Mine was pretty bad so I soldered wires onto the board and put a new connector between the PS and board. You might try unscrewing the bottom board and reseat it into the top board a couple of times. As previously stated, the first thing to do would be check the 5 volts on the board. You anywhere near I-95? I am probably heading up to Brooklyn in a few months, if you can wait that long.

 

[machfelon]

If the garbage appeared after you swapped joysticks, it might be something simple. One guess is that the the pcbs or power connector got jostled when you swapped joyticks. Those power connectors at the bottom of the pcb set can get rather oxidized. Mine was pretty bad so I soldered wires onto the board and put a new connector between the PS and board. You might try unscrewing the bottom board and reseat it into the top board a couple of times. As previously stated, the first thing to do would be check the 5 volts on the board. You anywhere near I-95? I am probably heading up to Brooklyn in a few months, if you can wait that long.

Im 20 mins from exit 11 on NJTP (i95)

 

[That80sGuy]

If you haven't realised it by now... any game you get..no matter how well it works now..will eventually break down. Your best weapon against the frustration and money drain is to get educated and fix them yourself.

 

[EVB]

hmmmm.... Does 720 show random sprites/characters when the joystick is not plugged in? My I,Robot does. Maybe the connection to the joystick is crappy. I'd just go though all the obvious stuff like connections, reseating socketed chips reflowing power pins with new solder etc.. before declaring defeat.

 

[Clytor]

Im 20 mins from exit 11 on NJTP (i95)

If you still need some help when I roll through, I'll stop by.

 

[khabbi]

How long have you been collecting? If this is the first game that you've bought that's had issues and put you over what it's worth, you're doing good. It's part of the hobby, and it happens.

From this post about being pissed about having a random problem like this, I would suggest never buying a Vector game. You'll spend a lot more time being pissed.

Best of luck with your 720, they are known to be problematic but when you get them working 100%, it's worth it.

 

[machfelon]

How long have you been collecting? If this is the first game that you've bought that's had issues and put you over what it's worth, you're doing good. It's part of the hobby, and it happens.

From this post about being pissed about having a random problem like this, I would suggest never buying a Vector game. You'll spend a lot more time being pissed.

Best of luck with your 720, they are known to be problematic but when you get them working 100%, it's worth it.

No I started collecting in 2006. I have owned: Gauntlet Legends, Gauntlet, Atari 720 (This is my second one), Dragons Lair, Tempest Cabaret, Ms Pacman x 2, Donkey Kong Jr, Defender, Centipede x 2, Capcom vs SNK, and a bunch more some in my signature.

This has given me the most trouble of them all. So this "aint my first rodeo".

 

[machfelon]

Just tested the +5V on the switching power supply and am getting 5.39

This is high Im sure. Do I just turn down the knob slightly and retest with game on? Or do I turn it down with game off then turn back on and retest?

 

[MKplayer1start]

Just tested the +5V on the switching power supply and am getting 5.39

This is high Im sure. Do I just turn down the knob slightly and retest with game on? Or do I turn it down with game off then turn back on and retest?

With the game on you turn the knob down. 5.39 sounds very high but I don't know that game specifically. I think a normal range is 5.1 - 5.10

 

[Jedidentist]

Get it down to 5.06-5.07. Then look at your video board, and with it on, see what your +5v is running. Both it and the CPU pcb have tabs marked +5v and GND. If they're both about 5.06-7, then you don't have a voltage drop issue, but if they read 4.9 or less, then you have part of the same problem that I have...which I'm going to try to correct by replacing my connectors. I've seen 3 720 video PCBs and 2 of them had burnt connectors...and the 3rd had already been replaced. I don't know what the issue is, but historically it seems like these games get big voltage drops because of the connectors. Ops probably jacked up the voltage on the PS and eventually that messed up the Leta chips or crystals or whatever keeps dying on these boards.

 

[machfelon]

Get it down to 5.06-5.07. Then look at your video board, and with it on, see what your +5v is running. Both it and the CPU pcb have tabs marked +5v and GND. If they're both about 5.06-7, then you don't have a voltage drop issue, but if they read 4.9 or less, then you have part of the same problem that I have...which I'm going to try to correct by replacing my connectors. I've seen 3 720 video PCBs and 2 of them had burnt connectors...and the 3rd had already been replaced. I don't know what the issue is, but historically it seems like these games get big voltage drops because of the connectors. Ops probably jacked up the voltage on the PS and eventually that messed up the Leta chips or crystals or whatever keeps dying on these boards.

Mine wont boot stable until I hit 5.54V on the switcher. At this Im at 4.5v on the PCB. Game is running (no joystick function tho). Im debating whether to just turn up the switcher higher to get normal V to the board. Granted its the wrong way to do it but want to see if that then allows the joystick to function since Im real low on the board at 4.5.

I jacked it way down to the 5.09 range on the switcher and I had 3.9 on the pcb and garbage all over the screen. Im losing a lot of voltage.

 

[Jedidentist]

It's tricky to balance, but if you can get your bottom board out, measure one of your 5v wires where it connects to the board. Find out which pin it connects to and put your red lead on the solder side. If you're getting the same voltage as the rest of the board, then that's where your voltage drop is. Since nothing other than that little metal pin is getting the brunt of the voltage, I wouldn't imagine that you could hurt the board by turning up the voltage...since the board isn't getting what the PS is putting out. That being said, I'm not an electronics guy...I'm just going by my own extremely limited experience. If your voltage drop is not at the pins, then don't turn it up.

 

[Jedidentist]

Okay, I just spent 3 hours today desoldering and resoldering the power supply connector pins on the video and CPU PCBs and then replacing all the ends on the wires. By replacing the pins and connectors I was able to drop the voltage necessary for my switcher to get 5.03V on my boards from 5.41V to 5.21V. So, bad/old pins resulted in a .2V drop in power. Don't know what that might do to help anything, but I thought I would pass it along.

 

[Hornet303]

Let me see if I understand. I am in a similar boat with my 720. I have to crank up the power supply greater than 5v to get the boards to be stable.

You replaced the pins on the connectors (the metal things inside the connectors that sit on the headers) and unsoldered the header (attached to the PCB boards), replaced the headers (resoldered)? This only gave you a .2 volt increase?

I have all the parts and tools to do this to my machine, but having a terrible time finding a block of time to do all this.