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Author Topic: Enterprise does not power on anymore (Read 6453 times)

Offline edoz

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Re: Enterprise does not power on anymore
« Reply #30 on: 2015.December.19. 00:17:30 »
When the non working situation: measure +5v on one RAM chip onboard (pin 8-16), one RAM chip at the expansion board, on U25 (this is at left bottom corner, pin 10-20), and on ROM chip (pin 14,28).

-On the one of the RAM chips (U10 and U14) i have 5v but some times also 0.10V on pin 8 and 16 (most rights pins?)
(And i notice that the screen is not always black but sometime flicker color lines
-On U25 most right pins (10,20) i have 5v
-On the ROM chip (I think you mean above the Z80 i have on 14 and 28 (also most  right pins?) 0 Volt or sometimes 3V

(all in a non working situation...)

seems that the power is not stable ?

Have fun with the Z80!

Offline edoz

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Re: Enterprise does not power on anymore
« Reply #31 on: 2015.December.19. 00:46:17 »
Ok.. i had also a moment that the enterprise was working and i was able measure also:

In this situation:

3 Volt on the rom
on the ram u25 most stable 5V
on the ramchips u10/14 4v

Especially in the not working situation the voltage on the ROM chip is very unstable. And also for the memory u10/14
The u25 gives always good 5v
Have fun with the Z80!

Offline Zozosoft

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Re: Enterprise does not power on anymore
« Reply #32 on: 2015.December.19. 08:14:12 »
Yellow point the GND pins, red are the +5V pins:
14381-0

Offline Zozosoft

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Re: Enterprise does not power on anymore
« Reply #33 on: 2015.December.19. 11:00:55 »
Quote
seems that the power is not stable ?
Are you measured on the marked pins?

If yes, and no 5V, then I think problem with the 7805 power regulators. Check the pins not are broken, check the solder points. If no any then try to replace these.

Offline edoz

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Re: Enterprise does not power on anymore
« Reply #34 on: 2015.December.19. 11:24:09 »
Are you measured on the marked pins?

If yes, and no 5V, then I think problem with the 7805 power regulators. Check the pins not are broken, check the solder points. If no any then try to replace these.


Zozosoft thank you for all the support!

Many thanks for the Picture with the yellow and red spots!! I measured on the WRONG pins. Now i did it again on the once of your picture!

And they ALL have a STABLE 5 V So that seems to be fine.


I'M sorry to say but all the time my enterprise behavior is different! First i had only a BLACK screen but now i have every time a not stable screen and the keyboard is working again. So it seems that the Enterprise is booting but not giving a stable picture now. I have no idea why the behavior is so different every time i power up. Maybe there is something else. I re- Soldered the 7805 again to be sure of the solder pins.




This is the Video Output! The last 10 hours i see this all the time when i am starting the enterprise. (before that i had only a blackscreen and no video output)

Now i have this screen and keyboard sound. So it seem the enterprise is still alive! but needs some attention ;)





I'm getting crazy. I'm sure it is not the video cable as sometimes it is working good.. (but say out of 2/100 times)
Have fun with the Z80!

Offline Zozosoft

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Re: Enterprise does not power on anymore
« Reply #35 on: 2015.December.19. 11:43:49 »
Now it is looks problem with the video +12V. Check it on U35, yellow GND, red +5V, blue +12V.

If the +12V only at about 9V, then TR2 are dead. It is can dead when previous problem with +5V. Also can be dead if C9 capacitor dried out. (But Your board have the better type capacitors, the C9 problem usualy with board which use Philips capacitors.)


Offline edoz

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Re: Enterprise does not power on anymore
« Reply #36 on: 2015.December.19. 12:03:14 »
Now it is looks problem with the video +12V. Check it on U35, yellow GND, red +5V, blue +12V.

If the +12V only at about 9V, then TR2 are dead. It is can dead when previous problem with +5V. Also can be dead if C9 capacitor dried out. (But Your board have the better type capacitors, the C9 problem usualy with board which use Philips capacitors.)

hmm i checked the blue, yellow and red points. They give solid 12 and 5 V.

About the C9? How can i measure this one if it works correctly?
Have fun with the Z80!

Offline Zozosoft

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Re: Enterprise does not power on anymore
« Reply #37 on: 2015.December.19. 12:05:30 »
hmm i checked the blue, yellow and red points. They give solid 12 and 5 V.
And you still got that crazy screen? :shock:

Offline edoz

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Re: Enterprise does not power on anymore
« Reply #38 on: 2015.December.19. 13:22:08 »
Yes the display output is now always like this. Is there something else I can check?
Have fun with the Z80!

Offline Zozosoft

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Re: Enterprise does not power on anymore
« Reply #39 on: 2015.December.19. 15:23:59 »
And the system looks runing (with broken screen)?
For example enter this BASIC program:
10 PING
20 GOTO 10
This is make some sound while running.

Offline edoz

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Re: Enterprise does not power on anymore
« Reply #40 on: 2015.December.19. 19:12:02 »
Yes it works! .. seems that i now only have this strange video output somehow.
Have fun with the Z80!

Offline IstvanV

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Re: Enterprise does not power on anymore
« Reply #41 on: 2015.December.19. 19:25:03 »
Could it be a problem with the NICK chip or its power supply ? It does not only look like there are issues with the horizontal sync, but it displays corrupt pixel data (character set), while the colors are correct.

Offline Zozosoft

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Re: Enterprise does not power on anymore
« Reply #42 on: 2015.December.19. 19:42:45 »
Could it be a problem with the NICK chip or its power supply ?
About the power supply: this is why i suggested check the +5V at different points, for check both +5VA and +5VB are working.

I think at this point need scope for check Nick signals.

Offline edoz

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Re: Enterprise does not power on anymore
« Reply #43 on: 2015.December.19. 19:58:55 »
Could it be a problem with the NICK chip or its power supply ? It does not only look like there are issues with the horizontal sync, but it displays corrupt pixel data (character set), while the colors are correct.

The picture does not show characters but if you look good it seem that they are there..
Have fun with the Z80!

Offline edoz

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Re: Enterprise does not power on anymore
« Reply #44 on: 2015.December.19. 20:00:12 »
About the power supply: this is why i suggested check the +5V at different points, for check both +5VA and +5VB are working.

I think at this point need scope for check Nick signals.

Which one is the NICK chip again? I don't own a scope :( but maybe i can barrow one. If i have one what do i need to do?
Have fun with the Z80!