Whirlwind display issue

shardian

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Okay, this one is really perplexing me.

Display is out. I've seen it work a few times, but then fade back out. Checked the HV section - -100 large resistor was no good (open), +100 resistor was out of spec high. With displays unplugged, voltages are okay. With display plugged in, -100 goes way down. I rebuilt the HV section, and went over the displays with a fine tooth comb.

You see, someone (poorly) replaced the display glass once upon a time. I went through and checked for shorts, then continuity checked connection. I did find one cut trace that I jumpered.

Still, no dice. The last time I turned it on, I saw sparking on the 3 leg chip on the heat sink in the -100 circuit.

Now for the weird part:
1. The fuse never blows
2. Testing the HV circuit immediately after power down the 2W resistor tests open or higher resistance. If I wait a while, it tests okay. I assume it has something to do with the spark I saw on the heat sunk chip.


So...what is going on here? A shorted display should pop the fuse, right? I put brand new 1/8 fuses in, so I know they aren't over rated.

I think I'm gonna have to buy a new display. If anyone has a working sys11b display, I sure could use one! I'd rather not pay $200 for a pinLED display.
 
1. replace sparky!

2 replace large resisters

at this point it will either work or blow the fuse , if it blows the fuse then you can troubleshoot without confusion
 
Honestly, in all the System 11 machines I have had, when displays stop working, I replaced them with PinScore LEDS. Some think they are too bright, but a little tint over the display windows clears that up.

I have never had good luck 'fixing' display issues, but you are likely MUCH more technically savy than I am :)

Hope you can get it working. That is a great machine and they lose alot when the displays are out :(

Chris
 
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HV is shorted to about -18 volts now even with the displays unplugged. So long $6 rebuild kit!

That display board is crap - gotta be the problem. I hate it when people do major board repairs that have NO BUSINESS wielding a soldering iron. It just ruins my day!

I'm gonna order the Pinscore displays.
 
There are 2 large caps that are not part of the rebuild kit. Fixed my display problems, might help you?

Your issue was similar to mine?
If the display glass weren't so horribly mangled, I might think about those caps. However, before I hooked up the displays I had perfect voltages. Then after hooking up the damage has been done. If it were caps, the issue would have presented itself w/o the displays present.
 
My display works great except the the top right angle segment on all "positions" is missing... not sure how to fix that.
 
HV is shorted to about -18 volts now even with the displays unplugged. So long $6 rebuild kit!

That display board is crap - gotta be the problem. I hate it when people do major board repairs that have NO BUSINESS wielding a soldering iron. It just ruins my day!

I'm gonna order the Pinscore displays.

i was only trying to help...
 
But dude, that's $200 of profit you'll lose when you sell it! PinLED's might be worth it for someone who doesn't want to mess with repairs, but you pride yourself on repairing games. Don't cave in on the PinLED's just yet!

Wade

I think the damage was done on a certain chunk of solder pads on one of the display glasses. I had to gouge out between the pads to make sure they weren't shorted. There's nothing I can do with damaged plasma glass - even if I could buy new ones, they are $100+ apiece!!!


Rottendog displays are only $150. They're good enough for me. I don't feel like paying $50 extra for a 20 cent potentiometer to adjust brightness thanks...
 
i was only trying to help...

Sorry for being a little harsh dude. It's just that blindly throwing parts at a problem is not a great way to troubleshoot.

On the flip side, spending 10 hours tracing down something only to find the display is shorted also isn't a good use of my time.
Anyone feels differently can feel free to shoot me minimal 'core charge' funds to tackle the display themself.
 
Sorry for being a little harsh dude. It's just that blindly throwing parts at a problem is not a great way to troubleshoot.

On the flip side, spending 10 hours tracing down something only to find the display is shorted also isn't a good use of my time.
Anyone feels differently can feel free to shoot me minimal 'core charge' funds to tackle the display themself.

parts that are sparking....TRANSISTORS, are not blind.....meaning they arent good

you said so yourself when you proclaimed 6bucks wasted, now did your problem start there...no, but it need to be replaced, you missed my point earlier, send that bisnatch to me ill fix it, having a spare is worth some time
 
parts that are sparking....TRANSISTORS, are not blind.....meaning they arent good

you said so yourself when you proclaimed 6bucks wasted, now did your problem start there...no, but it need to be replaced, you missed my point earlier, send that bisnatch to me ill fix it, having a spare is worth some time

The problem is not on the power board...replacing the transistor will just result in it getting fried again. The problem is on the display board which is in turn stressing the -100v supply. So yes, replacing that transistor when I know it will just burn up again solves nothing.

If you want the existing display, paypal me $20. PM me and I'll hook you up with my info. If you're able to fix it, you just got a great deal. It's likely you will since I have seen it work a few times. If you can't fix it, then have fun rebuilding your HV -100 circuit a few times.
 
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