Centipede with no video/sound

[Auric]

Hey gang,

I have a Centipede I'm working on that is having issues. The PCB, monitor and everything have power, but I get no audio and no video on the monitor. The game is set on free play and I can tell it's 'running' when I press the the 1 player start as I've timed it and played blindly and gotten the game to go back to free play mode (game over with 1/2 player buttons flashing) and at different intervals (meaning I died faster in one game, etc).

I've replaced the 'big blue' capacitor at the bottom but that yielded no new results.

I welcome any ideas as to what to diagnose/investigate. I've run out of ideas.

Thanks!

Dave

[SirPeale]

Pics of inside, plz.

[Auric]

As requested, I took several photos of the inside, they can be viewed here:
http://www.flickr.com/photos/hernly/sets/72157615511163200/

The hackery you see with the one cap in the middle actually works. The previous owner did that as a quick fix. I have not yet made it permanent as I'm not sure if I have to replace the cap or not. I did test to ensure that it (the connection) is sound despite the appearance.

Thanks!

Dave

[SirPeale]

Does the monitor have neck glow?

What kind of monitor is it?  You didn't take pictures of it.

[Auric]

Sorry It's an Electrohome G07 model. It does not have neck glow, no. There is however a blank signal on the display (the display is all black, but it's clear the monitor is on, if that makes sense).

[Kevin Mullins]

It does not have neck glow, no. There is however a blank signal on the display (the display is all black, but it's clear the monitor is on, if that makes sense).

Ok, those two statements don't go together..... if you can tell that it's on then there should be neck glow. It may be very faint and you're just overlooking it.
Try turning the SCREEN voltage up which is the bottom potentiometer on the flyback.
If there is no video signal it should just turn whiter/brighter.

but I get no audio and no video on the monitor.

I would start by checking the monitor chassis for bad solder joints, especially at the video input connector.
Then take a close look at the ARII board, which is the one with the "cap fix" for burnt resistors, etc.
Also clean and re-seat the edge connector on the game pcb. Make sure it has a good clean and tight connection.

[Auric]

It does not have neck glow, no. There is however a blank signal on the display (the display is all black, but it's clear the monitor is on, if that makes sense).

Ok, those two statements don't go together..... if you can tell that it's on then there should be neck glow. It may be very faint and you're just overlooking it.
Try turning the SCREEN voltage up which is the bottom potentiometer on the flyback.
If there is no video signal it should just turn whiter/brighter.

I agree which is what is throwing me off. I've tried looking for neck glow with no lights on in the room, resulting in a faint glow from the front of the monitor, but none from the neck. I know it sounds backwards, but I swear it's what I'm seeing.

but I get no audio and no video on the monitor.

I would start by checking the monitor chassis for bad solder joints, especially at the video input connector.
Then take a close look at the ARII board, which is the one with the "cap fix" for burnt resistors, etc.
Also clean and re-seat the edge connector on the game pcb. Make sure it has a good clean and tight connection.

I've already re-seated the connector, but I will look at the ARII board for anything else.

[SirPeale]

So, if you crank the screen control to the max, you should get a white screen with retrace lines.  Is that correct?

It's also possible you've got board issues that aren't allowing video to output to the screen correctly. 

[Auric]

True, but then that doesn't explain the lack of sound, either.

I'm going to look the board over now and report back shortly

[SirPeale]

So do you get white screen with retrace? 

Stupid question...is the volume turned down?

[Kevin Mullins]

Another thing to maybe keep in mind is I know you said it was set to freeplay..... so the player start buttons will automatically start blinking.

But they will also do that when there is an error.
(at least I believe a Centipede will like most Atari's of similar age)

So when you say you think/know it is playing blind.... do the player start buttons blink and then stop blinking when you select one of them?
(or describe the sequence a bit more if you can)

Gotta realize we're all trying to visualize these events since we're not standing at the machine.

[Auric]

Another thing to maybe keep in mind is I know you said it was set to freeplay..... so the player start buttons will automatically start blinking.

But they will also do that when there is an error.
(at least I believe a Centipede will like most Atari's of similar age)

So when you say you think/know it is playing blind.... do the player start buttons blink and then stop blinking when you select one of them?
(or describe the sequence a bit more if you can)

Gotta realize we're all trying to visualize these events since we're not standing at the machine.

haha yeah I visualize and I'm *at* the machine

When the buttons are blinking and I select 1Player, they stop blinking and the 1Player stays lit. It remains for a time then goes back to blinking. The length of time varies greatly. That tells me that the men are dying at different rates. I could certainly be wrong.

Also: I checked the ARII board and I saw no obvious burn damage. I *did* find one thing that I've been miss-reporting. The monitor (not the neck) has glow to it that is faint. This is consistent even when the unit is OFF, so it has nothing to do with the game being on or even running. Almost like it's *really* charged up. Never seen that before. The glow slowly dissipates over time when power is disconnected. During all of this I've never seen the neck glow.

My problem is that I'm repairing this for a friend and don't know the machines prior history. So I don't know what behavior it had when running. Aside from the monitor there is still no audio as well. I've checked the volume and the speaker connections. Can you tell I'm having fun?

Thanks guys!

[SirPeale]

Will you /please/ do me a favor and turn the screen control up already!  This is so I can eliminate some stuff and move on to other stuff.

[Auric]

Will you /please/ do me a favor and turn the screen control up already!  This is so I can eliminate some stuff and move on to other stuff.

No adjustment on the monitor yields any change whatsoever. Thought I had mentioned that. My bad...

[Kevin Mullins]

What make/model monitor does it have in it ?

Have you tested the speaker with anything else ?
(at least Ohm it with a meter)

[Auric]

What make/model monitor does it have in it ?

Have you tested the speaker with anything else ?
(at least Ohm it with a meter)

It's an Electrohome G07 monitor, and I've tried a brand new speaker that I know works (tested it in other games). I just can't get why I don't have sound or video both. I can see the monitor being dead... but no audio either... grumble grumble

[SirPeale]

Will you /please/ do me a favor and turn the screen control up already!  This is so I can eliminate some stuff and move on to other stuff.

No adjustment on the monitor yields any change whatsoever. Thought I had mentioned that. My bad...

Okay.  Well, the first thing you'll want to do is make sure you have a working monitor.  For all you know the game is working fine, but you have no sound for another reason.

Since it's a G07, I'm sure it's all original, so you'll need to completely recap it.  Also check the fuses and see if either of them are blown.  After you check the fuses, let us know which are blown.

It'll probably need a new flyback too, but let's burn that bridge when we come to it.

[Auric]

Okay I'll recap it, check the fuses later tonight and report back. I have the kit for it.

[SirPeale]

Check the fuses first.  Depending on which fuses are blown the repair approach is different.

[ChadTower]

Yeah, don't risk introducing a new problem by capping it before you even get a picture.  See if you can get something on screen before you go replacing any caps.

[SirPeale]

Yeah, don't risk introducing a new problem by capping it before you even get a picture.  See if you can get something on screen before you go replacing any caps.

It's a bit different with a G07.  There are a couple problems that can blow a fuse on a G07 if certain caps are bad, IIRC.

[ChadTower]

Yeah, don't risk introducing a new problem by capping it before you even get a picture.  See if you can get something on screen before you go replacing any caps.

It's a bit different with a G07.  There are a couple problems that can blow a fuse on a G07 if certain caps are bad, IIRC.

That's true, but if he solders one in badly, or backwards, now he has a new problem he didn't have before.  At least if he knows the fuse is blowing then he can go to those caps and replace them.  What if the fuse wasn't blowing before but it does after recap?  Or if he opens a bunch of currently working but cold solder joints by handling the chassis too much?  He'll recap it for sure but for now it's best to just take one thing at a time and finding the problem is priority over general caps (even if the problem may actually be a cap).

[Auric]

Just to give everyone an update...

I was of the same opinion as to *wait* and recap the monitor until I had something... anything... on screen. I checked the fuses last night and they were OK. I then proceeded to recap the board. Upon hooking everything back up... I first thought it was no joy. After about 60 seconds I noticed some differences so I turned up the screen and POOF we have a picture. After making a few adjustments I got the picture looking really solid.

I do still have no audio, so that's my final issue to resolve. Otherwise the game plays great.

Thanks to all for your input... I just wished I'd of recapped it as soon as I had the cap kit.

[ChadTower]

Peale called it! 

[Kevin Mullins]

Peale called it! 

 


A couple things to check for the audio.......

The volume pot itself.

The ARII board. (Audio / Regulator board)

Output from the game pcb itself.

[RayB]

The connector.

The wiring.

...

[SirPeale]

Outstanding.

As noted, check the volume POT (measure with a meter) and your voltages.