Asteroids G05-805 no image

opt2not

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After working a while on my asteroids restoration, I've finally got to a point where I've hit a dead end.

My Asteroids plays blind. I've got a verified working Asteroids PCB.
My G05-805 has no image displayed when the game is running. Spot-killer is LED lit, lamp heater is glowing strong, and I hear chatter from the monitor, and buzz/noise from the HV section. Fuses checked good. No burning, no smell. Just nothing on screen.

I flipped the switch for test mode, and checked my PCB voltages, I get a solid 5.1v from the 5v tap. My X, Y and Z voltages seem pretty low fluctuating between -1.2 and 1. But the funny thing is, this board is verified working! Hooked it up to my friend's machine and it played fine.

So this leads me to believe my Power supply may not be giving me the right amount juice. I checked my voltages on the A/R board, nothing there that looks out of wack. Getting 5.3v on the 5v line, and 14.3 on the 10v line (not under load).
The board seems to be running fine with these voltages, as I can hear the game play properly without any hiccups.

Doing some more digging, I noticed the B&W monitor faq recommends checking the P100 connector for readings.
30 VAC should be on pins 7 and 10, but I'm getting nothing! Zero. Same thing for the 6.3 VAC line!
Tracing the wires, I believe these come directly from the power block, and not through the A/R board. Am I correct in this?

If so, then my block could be the culprit.

I pulled my block out, checked the small Rectifier board that has two saucer-style diodes. Removed the diodes from the board and check it with my Diode test on my multimeter. Got between 400-500 one-way on both, no readings the other way. So I'm assuming the diodes are still good. (can someone verify this for me?)
Fuses checked good, I've got a new fuse-block installed on it, checked all my connections as well, all fine.

The only other hardware on there is the EMI filter, and the fat Isolation Transformer.

Could it be the Isolation Transformer? Is there any other test I can try to find why I'm not getting and VAC to the monitor lines?
 
Ok

Check out this diagram

Click for full size


It shows 65VAC and a centre tap

It means you should have approx 30VAC from GND to either pin 7 or 10 on P100

Look at this one



It shows where it goes

Do you have 30 vac to gnd (IE : Between pins 8 and 10, then 8 and 7)?
 
Thanks dezbaz.

Looks like I was reading the P100 pins incorrectly. I can verify I'm getting 30 vac to gnd on those pins.

On the Deflection board, I've done:

- a full cap kit. Checked and rechecked my work to make sure they were installed right.
- Continuity check on all Fuses - check out good as well.
- Re-soldered the header pins to make sure there were no cold or cracked solder points.
- Tested DB100 - checked out good.
- Spot-checked all components for burns, or faults - none that I can see
- Checked continuity between all traces, checked for breaks - again checked out good
- Replaced all chassis transistors on the metal frame, made sure they were mounted securely and not shorting


On the HV board:

- Installed cap kit
- Checked all diodes and the few small transistors on the board - good
- Checked the two transistors attached to the HV case (q900, q903) - good again
- Cleaned up the Anode cap, and diode connected to it - there is a slight darker colour around the diode, but I don't see any burning indication.

Could my problems be with the HV diode connected to the anode (D904)? How do I go about testing this? I pulled the diode out and connected my DMM to it using the standard diode test, but was getting no readings either way. I'm assuming this is a special diode that I'm not testing correctly.

Any additional suggestions would be appreciated. In the meantime I'm going to pour over the B&W FAQ again and see if I'm missing something.
 
Here's a few pictures of the boards. Perhaps someone might see something I've overlooked?


index.php


index.php


index.php
 
If your spot killer is on then you have a problem on the deflection board if the motherboard tested good.

I would ( if you have not done it yet )

1. replace fuses on the deflection board if they are old, even if they meter good, and while you have them out resolder the fuse holders.
2. Meter and resolder all the larger resistors.
3. Check the transistors ( or just replace them) that are mounted to the 4 heat sinks. They are mpsu07 and mpsu57's. Get the heavy duty ones from Bob Roberts.
4. Replace the x and y adjustment pots. I have seen a bad pot cause collapse and the spot killer to come on. Even try turning these pots back and forth a few times and then turn the game on and then try adjusting them slowly and watch the led and see if it goes off while you turn them.
5. Check for broken wires where they connect to the chassis mounted transistors.

I would save #3 for last.
 
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Lightly wiggle all of the connectors, and even each wire in each connector (with the power on, and game PCB connected, and someone watching the monitor) to see if the display appears.

I've had a problem with one of the CRT grid voltages not making good connection at the header coming out of the HV cage. The display would disappear totally, even though the chassis deflection, HV, etc. was all working fine.
 
If the spot killer is lit up then I would think it has nothing to do with the HV cage wires. All he has to do is watch for the spot killer to turn off. That should mean the picture is on.
 
I would caution you as it looks like it may be overfused. F600 and F700 are supposed to be 2 amp. You may be masking a problem that SHOULD cause a fuse to blow.
 
O wait, I remember again, it has D100 on the solder side....for some weird reason...

It's the last diode in B+ so it would definitely not work without it...
 
Do you have neck-glow ?

If you have no 6.3VAC you'll never get a picture as the heater won't work...

The 6.3 VAC may also be used for the coin door lighting....maybe one of the fuses blew ?
 
Whoa, lots of responses. Thanks, you guys rock.

If your spot killer is on then you have a problem on the deflection board if the motherboard tested good.

I would ( if you have not done it yet )

1. replace fuses on the deflection board if they are old, even if they meter good, and while you have them out resolder the fuse holders.
2. Meter and resolder all the larger resistors.
3. Check the transistors ( or just replace them) that are mounted to the 4 heat sinks. They are mpsu07 and mpsu57's. Get the heavy duty ones from Bob Roberts.
4. Replace the x and y adjustment pots. I have seen a bad pot cause collapse and the spot killer to come on. Even try turning these pots back and forth a few times and then turn the game on and then try adjusting them slowly and watch the led and see if it goes off while you turn them.
5. Check for broken wires where they connect to the chassis mounted transistors.

I would save #3 for last.

Excellent tips. I'll go down the list and see if I find anything. I know that #5 isn't the case since checking continuity was one of the first things I did. Though I think #2 and 4 are things I should have done too. I will get on those and report back.

alexred said:
I would caution you as it looks like it may be overfused. F600 and F700 are supposed to be 2 amp. You may be masking a problem that SHOULD cause a fuse to blow.

At the same time of ArcRevival's #1 tip, I'll make sure I have the correct ones. I didn't bother to even check the types I had, and just assumed they were correct since they weren't blown. But of course, first thing to do is not assume whomever worked on this before did the right things.

DarrenF said:
Lightly wiggle all of the connectors, and even each wire in each connector (with the power on, and game PCB connected, and someone watching the monitor) to see if the display appears.

I've had a problem with one of the CRT grid voltages not making good connection at the header coming out of the HV cage. The display would disappear totally, even though the chassis deflection, HV, etc. was all working fine.
Yeah, i tried this too. Couldn't get anything to show, nor have the spot-killer turn off.
I don't think it's a connection problem, especially after doing a mass continuity test.

Level42 said:
Do you have neck-glow ?

If you have no 6.3VAC you'll never get a picture as the heater won't work...

The 6.3 VAC may also be used for the coin door lighting....maybe one of the fuses blew ?

Yes, I have a good neck-glow, monitor chatter, and a slight buzz/noise coming from the HV section.

One other thing I noticed, if I let the game and monitor run for a 5+ minutes then shut it off, I can see a very faint small dot travel from the lower-right of the screen, to the center, then fade away. It's very faint though, and I haven't been able to make it happen consistently.

Level42 said:
It's the last diode in B+ so it would definitely not work without it...
I used my DMM's diode test on the DB100, didn't get any weird readings. It was all flowing in the right directions and not in reverse. Should I be testing it out-of-circuit?

omegaman said:
Are the transistors on your deflection in the wrong way around because they are equivalent but not identical to the TIS98's ?
Do you mean the transistors attached to the heat-sinks? Q706 and the like, or the ones attached to the HV cage?
 
No, I was talking about the small black transistors on the deflection board. They look to be the wrong way around.....I'm guessing you have used a similar transistors to replace the tis98's(original) and those transistors have emitter and collector the other way around.
compare Level42's board to yours. It would be worth checking.
 
No, I was talking about the small black transistors on the deflection board. They look to be the wrong way around.....I'm guessing you have used a similar transistors to replace the tis98's(original) and those transistors have emitter and collector the other way around.
compare Level42's board to yours. It would be worth checking.

Nicely picked up

def-G05-805.jpg


There are quite a few around backwards
 
Geez....how did I miss that ! Well at least it was a good idea to upload my pic as well ;)

Small not to Opt2not: Look at the transistors housing, and the symbol printed on the PCB. Both have a flat side. Normally, the flat side of the transistor should match that of the printed symbol...not sure if you knew that....

Could be different transistor types though and this was done on purpose....I mean....you can maybe mix-up one time, but so many ??

About the diode: I only mentioned it because it seemed to be missing from my board. If you tested it like that I'm pretty sure it's good.

By the way, your board looks like new, very clean. Did you wash it ?
 
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By the way, after I cap-kitted mine, I had no picture anymore unless I turned up the brightness completely, and then I got a picture with all the "retrace" lines and a very bright spot in the middle. I immediately turned it back so I could barely see the spot..and next turned it off.

Checked the B/W vector faq and what I really didn't expect: the LED had shorted (was normally working before the cap-kit) and also the transistor that is before the LED....no schematics here at work...
To check, I first removed the LED, and sure enough the monitor was working great again.

So I replaced the LED and back to square 1 (no picture), that's how I found out about the bad transistor.
I removed that and was working fine again, however, the spot-killer won't work without the transistor...still have to solder a new one in there (got 'm now) ....
 
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