Roached a Maxim ??

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astrocaver
 
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Roached a Maxim ??

Post by astrocaver »

I measured 56 VDC, so continued with the next steps, but the IV-18 digits failed to light.
The clock didn't beep, and was crowbarring the supply.
So I unplugged the tube and the Maxim chip and Q3, but the problem remained.
I confirmed a dead CPU so ordered a few from Avnet... with a freshly-burned 168, it beeps on boot and I get 56V again.

But with the Maxim chip installed, I only get 14VDC at the HV instead of 56.
I assume this means I have a roached Maxim chip.

Is there anything else possibly wrong, or should I order some Maxims ?

thanks

adafruit
 
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Re: Roached a Maxim ??

Post by adafruit »

well...it possible but remember that the maxim chip also loads down the supply so 15V isnt too unusual. it may be the tube instead. if you have a scope or multimeter check the output pins
also, not sure how you could possibly have a dead CPU. did you zap it with 50V?

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astrocaver
 
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Re: Roached a Maxim ??

Post by astrocaver »

OK - much better now.
With the tube plugged in, I get 56V at the zener.
With tube unplugged I get 14V after it settles.
The tube still doesn't glow, but this is progress.
I'll put Q3 back and go from there.
- - - -
As to zapping the 168, I remember it was taking a long time for the 56V to decay, so I may have continued with the build while HV was too high.... should have drained the HV cap with a 1K resistor.
I also recall the Maxim not seating flat at first... if that matters.
Since the initial problem, I've reheated lots of pins, so I may have fixed a bad connection or a bridge without identifying it.

thanks

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astrocaver
 
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Re: Roached a Maxim ??

Post by astrocaver »

Woo Hoo !
It works

This design is clever on many levels
Thanks for a great kit !

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