"555" replacement on the Amp HV PCB

As far as I know all 555 timers are all the same in an 8 pin DIP package. Hell, you can even get them at Radio shack for like a buck.
 
Yep - Radio Shack carries them. Before you go buy one though Measure the VR1 and VR2 shown in the Amplifone FAQ.
 
Actually I replaced them already. In fact the only items I did not replace at this point is the "555", the MCI and the flyback.
It's a friends HV PCB and he is using the Chinese replacement flyback. I use the Lexel and never had a problem.
All the caps are low ESR so that is not the problem, (I think??)
The problem is "pulsing" of the display. It comes and goes, actually oscillates. Steady to slightly wavy back to steady, especially around the edges of the screen. I am at a loss and am just shooting in the dark at this point. I'm hoping that replacing the 555 will do the trick.

So just to confirm, that replacement will work?

Is it true that all the "555"s are the same?


Thanks
Jeff
 
Low ESR is fine
Any 555 is fine - Radio Shack or NTE (or whom ever) they are the same.
As far as the Chinese flyback (Hoveyking) - I have used 4 and they have been perfectly fine. there is no proof your Lexan is any better than this one. Time may tell another story ;)

So you've checked the output voltages off the deflection board? If not disconnect your HV board and monitor the output voltage on your def board.
Or is this a known good deflection board?

You've eliminated the 0 ohm brown resistor right?

I assume you have a probe to set it to 19.5Kv right? What's it currently sitting at?
 
Yes, I am testing this in my working SW.

I replaced the jumper with wire as well.

I set the HV to 19.5KV

I ordered a couple of 555s' from Mouser and hopefully that will take care of the problem.

Thank you for the "555" confirmation.

Jeff
 
If all else fails, I have one of those "hoveykings" that I had gotten in a trade and will swap it as a last resort.
Thanks
Jeff
 
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