G05-802 HV problem

[drsoggy]

I'm still waiting on my HV diode, so I'm having a lot of time to think. I was told that the prob on my asteroids deluxe is either the HV diode or the transformer. The diode being the most logical place to start, so I'm waiting on that. The monitor yoke doesn't light up, and there is no chatter. I've read some reports where the yoke doesn't light, but they do get the vector chatter, and the problem was in the diode. I'm just curious if this indicates an additional problem w/ my monitor, or if its possible the diode could be the cause for both issues.

Thanks,
Scott

[D_Zoot]

In most monitors the heater voltage is derived from a secondary of the high voltage system.    In the case of a G05, the heater voltage is *not* derived from the HT circuit, but rather supplied by the power brick in the bottom of the cab.

So,  having a dead HT circuit, or bad HT diode, should not be causing a lack of neck glow (or heater operation).   Additionally, if the HT was the only issue, you should be getting deflection chatter (although it can be hard to hear).

I take it the spot killer is not lit on the deflection board?    If you unplug the game board and turn the machine back on, is the spot killer lit?  It should light with the game board unplugged since there is no signal coming into the monitor, if not the monitor isn't working at all.

Sounds like you may have some power related issues.   Good place to start would be to grab a schematic for your cab and verify the monitor is getting proper voltages.


D

[qrz]

suggest changing the 'lytics on the HV board while u have it open...
elevated ESR and value reductions are likely , and
resolder any questionable connections on both pcb's.

qrz

[drsoggy]

In most monitors the heater voltage is derived from a secondary of the high voltage system.    In the case of a G05, the heater voltage is *not* derived from the HT circuit, but rather supplied by the power brick in the bottom of the cab.

So,  having a dead HT circuit, or bad HT diode, should not be causing a lack of neck glow (or heater operation).   Additionally, if the HT was the only issue, you should be getting deflection chatter (although it can be hard to hear).

I take it the spot killer is not lit on the deflection board?    If you unplug the game board and turn the machine back on, is the spot killer lit?  It should light with the game board unplugged since there is no signal coming into the monitor, if not the monitor isn't working at all.

Sounds like you may have some power related issues.   Good place to start would be to grab a schematic for your cab and verify the monitor is getting proper voltages.


D

You said the deflection chatter can be hard to hear? What exactly does it sound like? Maybe I'm not hearing it. Thanks for the tip on unplugging the board. I will try that tonight. Lastly you say check the voltages going to the monitor. Can I unplug the molex going in to the monitor and test the correct pin to make sure I'm getting the correct voltage? Is that the proper way? Sorry if I sound like such a noob at this, but I'm learning.

Thanks,
Scott

[drsoggy]

Update:

When I unplug the board the spot killer does turn on. I also noticed some blue flashes inside the yoke, but I don't get a constant glow. There is also an electrical hum from the monitor which I'm sure is normal. Can anyone tell me what those blue flashes might be?! Is it arcing?

[qrz]

blue flashes inside the tube is likely arcing . gassy tube or vacuum lost ..
external arcing would likely produce a snap and/or the odor of ozone.
a loud 60-120hz hum would be cause for concern ( high load possible)
a faint hum not as concerning .....

qrz

[drsoggy]

I'm wanting to test the voltage going into the heater. Can someone help me out as to how to do this? If I'm correct I should take a reading at pin 9 and 10 of P500 on the deflection board, and pin #9 is the ground.  Am I right? Will I mess anything up if I do this?

Scott