Asteroids upright with G05-802 with no picture

Kiflow

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Donor 2017

VAPS


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Hi,

I have this asteroids upright and I feel like I'm close to getting it working...

- Flashing start buttons & game plays blind
- Has neck glow
- Nothing on the tube even after adjusting brightness & contract pots on deflection
- looked through FAQ

Deflection Board:
- No Spot Killer
- I had to replace a number of bad & burnt components on the deflection board, fuses & reflowed connectors
- Can hear deflection chatter

EHT/HV Cage - Replaced HV diode

What's the next step?
Is there a way I can verify if the transformer is gone?

Would appreciate any thoughts - thanks in advance
 
Let's see if your board is putting out video. Disconnect the monitor (the board could be over-driving the monitor and may have blown the transistors) and hook up an oscilloscope. Post what you get in test mode here.

Do you have an oscilloscope?
 
You say you replace the HV diode, but did you measure your HV? Usually the diode isn't what's actually bad on these, and you end up replacing a good diode. The problem is the springs get rusted, get resistive, and kill the HV. So you need to measure your HV to see if you actually have any, using an HV probe, and clean the springs and boots. If you work on vectors, you should have a probe. You should also recap the HV cage. Procedure to clean the diode boots and springs is here:

Myth Busting Thread

I have updated first post with some of the myths and their status. Will try to catch up and add some others but if you feel real strong about changing status of one, quote it and post a fact. The fun ones are fine but too many for me to try and update.
forums.arcade-museum.com
 
andrewb said:
You say you replace the HV diode, but did you measure your HV? Usually the diode isn't what's actually bad on these, and you end up replacing a good diode. The problem is the springs get rusted, get resistive, and kill the HV. So you need to measure your HV to see if you actually have any, using an HV probe, and clean the springs and boots. If you work on vectors, you should have a probe. You should also recap the HV cage. Procedure to clean the diode boots and springs is here:

Myth Busting Thread

I have updated first post with some of the myths and their status. Will try to catch up and add some others but if you feel real strong about changing status of one, quote it and post a fact. The fun ones are fine but too many for me to try and update.
forums.arcade-museum.com
Click to expand...

sounds like I need to bit the bullet and spend $500 on a HV probe and scope if I can find one
 
Look around and see what you can find. I picked up a scope and signal generator that work great for Asteroids. It's a Leader LBO-516 100 MHz scope - I paid $100 US for it, and it's perfect for Asteroids. You might be able to find one in your area down in Oz.
 
Kiflow said:
sounds like I need to bit the bullet and spend $500 on a HV probe and scope if I can find one
Click to expand...


You don't need a scope here. Just a probe. You can get a new BK Precision PR 28A for $75 USD.

If the spot killer LED is out, and then comes back on briefly when you press and hold the reset button on the game board, then you have deflection, and the deflection system is working. It just sounds like you are missing HV here.

You can also confirm there is signal from the game board with a DMM (though it looks like you have it). No scope needed here.
 
Thanks guys. I did check the springs to ensure good contact and clean the boot when I replaced the diode & checked it is the correct orientation. The spot killer comes on briefly when I reset the board. I've ordered a probe so I will measure the HV when it eventually arrives.
 
My probe arrived the other day. I inserted it under the anode as securely as possible, taped it in position, connected power and I get a reading of 0.0 Volts. So it looks like no HV!
 
Well, that's something. (Assuming your probe is good, and you're measuring it properly.) You might want to sanity check your tool, by measuring another monitor, just to be sure.

But you can also tell if there's HV, by holding your hand in front of the tube. Just in front of it, without touching it. Usually you can feel the static, like on an old TV.

And usually when you have HV issues, it's common to get *some* HV, like maybe 1kV. If you really have zero, you have more than just a diode issue. The cage may not be working at all, which could be a sign of other things wrong in the cage. You'll just need to troubleshoot it (or send it in).
 
Still no HV apparent on the tube. I'm at the point I would love to feel the HV lol kidding

I've checked the voltages on the P900 connection to the EHT (which I think supposed to be DC?) and I have:
31VDC on pin 8 (Red wire)
~0.1V on pin 5
~0.1V on pin 3
~0.1V on pin 1

Wondering if something is shorting & dragging down the voltage... I replaced the caps, checked diodes and reflowed the connector
 
What is the input voltage when the cage is not connected? It should be closer to 40V.

All other pins are outputs, or ground.

Sometimes the cage-mounted transistors can be bad on these. And sometimes the flybacks can be bad. You just have to test everything.

Did someone actually put the HV diode in backwards?
 
andrewb said:
What is the input voltage when the cage is not connected? It should be closer to 40V.

All other pins are outputs, or ground.

Sometimes the cage-mounted transistors can be bad on these. And sometimes the flybacks can be bad. You just have to test everything.

Did someone actually put the HV diode in backwards?
Click to expand...
I will test the voltage when the cage is not connected. I diode tested the transistors but I realised I have not tested or replaced the non electrolytic capacitors so I might remove & test them. Is there a way to check the cage transformer? The HV diode was in the right way
 
I've never seen any of the non-electrolytic caps fail in these. That's not to say it couldn't happen, but I'd say it's unlikely.

To test the transformer, I just measure the resistances of all coils (and connections between coils), side by side with a known-good cage.
 
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