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Author Topic: Enterprise does not power on anymore (Read 7438 times)

Offline endi

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Re: Enterprise does not power on anymore
« Reply #15 on: 2015.December.18. 16:03:33 »
First key click at the ENTERPRISE screen! :-)

hm volt nekem olyan asszem hogy ilyen szép szivárványcsíkos hibaüzenettel indult, ep logo se volt
de nem tudom mi volt ez, meg hogy nem-e csak álmondtam :)
Vigyázat! Szektás vagyok! :)

Offline edoz

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Re: Enterprise does not power on anymore
« Reply #16 on: 2015.December.18. 16:04:08 »
Huh! and now it is not starting anymore .. for one moment i saw the BOOT logo.. It seems that it sometimes working and sometimes not..
Have fun with the Z80!

Offline edoz

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Re: Enterprise does not power on anymore
« Reply #17 on: 2015.December.18. 16:13:28 »
The RESET gives 5 volt on the BUS..

So very strange it seems that the enterprise is sometimes starting and sometimes not. Maybe it is a power problem ?
Have fun with the Z80!

Offline gflorez

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Re: Enterprise does not power on anymore
« Reply #18 on: 2015.December.18. 16:20:03 »
Check the video cable at the edge connector, you can have some pin un-welded by the movement. 

Online Zozosoft

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Re: Enterprise does not power on anymore
« Reply #19 on: 2015.December.18. 16:21:05 »
The RESET gives 5 volt on the BUS..
Probably the multimeter too slow to detect the 0V pulse.

Quote
So very strange it seems that the enterprise is sometimes starting and sometimes not. Maybe it is a power problem ?
I don't think.

My first idea: open the machine and check the turbo switch circuit soldier points.

Offline edoz

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Re: Enterprise does not power on anymore
« Reply #20 on: 2015.December.18. 16:21:11 »
now invest deeper... (for some reason it is not booting anymore)

But i hear two sounds when i plug the powerplug in the enteprise..
One TIK sound from the speaker but also a small tick from some where from the motherboard.
(i have no idea where) is that also normal?
Have fun with the Z80!

Online Zozosoft

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Re: Enterprise does not power on anymore
« Reply #21 on: 2015.December.18. 16:22:36 »
One TIK sound from the speaker but also a small tick from some where from the motherboard.
(i have no idea where) is that also normal?
I think it is the tape relays. It is normal.

Offline edoz

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Re: Enterprise does not power on anymore
« Reply #22 on: 2015.December.18. 16:29:25 »
Ok yes. It sounds like a relay.. but i was not able to find it on the motherboard.

The wires of the turbo switch looks normal and good attached on the motherboard.
10 min. back when the computer was working i was also able to switch between turbo and normal mode so the switch looks fine.. Behind the power plug on the motherboard there is a small spool. It seems a bit damaged. (there is a small break in the iron) Could that be a problem?
Have fun with the Z80!

Online Zozosoft

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Re: Enterprise does not power on anymore
« Reply #23 on: 2015.December.18. 16:34:39 »
Ok yes. It sounds like a relay.. but i was not able to find it on the motherboard.
The two blue at the tape connectors.

Quote
The wires of the turbo switch looks normal and good attached on the motherboard.
Behind the power plug on the motherboard there is a small spool. It seems a bit damaged. (there is a small break in the iron) Could that be a problem?
Can you upload photos?

Offline edoz

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Re: Enterprise does not power on anymore
« Reply #24 on: 2015.December.18. 17:05:20 »
Ok .. here the picture of the mini break. it is very very small




Here you can see my monitor and a moment of working:




And something strange!! I notice when the COMPUTER is working that there is some sound from Those 2 guys.. a small grrrrrr .. (can't tell) but it is like a brom tone..

If the COMPUTER is not working this sound is not there .. (i'm not sure it's from them but it looks like that)

Have fun with the Z80!

Offline edoz

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Re: Enterprise does not power on anymore
« Reply #25 on: 2015.December.18. 17:13:54 »
Hmm no the sound is from the speaker. it is just background noise.
Have fun with the Z80!

Offline IstvanV

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Re: Enterprise does not power on anymore
« Reply #26 on: 2015.December.18. 20:21:45 »
on the motherboard there is a small spool. It seems a bit damaged. (there is a small break in the iron) Could that be a problem?

I think it is part of the circuit that generates the +12 V supply voltage, but with minor damage to the ferrite core it would probably still work.

Online Zozosoft

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Re: Enterprise does not power on anymore
« Reply #27 on: 2015.December.18. 21:54:44 »
Ok .. here the picture of the mini break. it is very very small
It is created from two half.
See these:
http://gafz.enterpriseforever.com/Galery/Alapgep/Picture/ISSUE5-4.jpg
http://gafz.enterpriseforever.com/Galery/Alapgep/Picture/ISSUE6-6.jpg

If it is really broken, then no 12V for PAL video ICs, then you got fast running colored screen garbage. But key sound still present in this situation.

Online Zozosoft

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Re: Enterprise does not power on anymore
« Reply #28 on: 2015.December.18. 21:58:29 »
Hmm no the sound is from the speaker. it is just background noise.
LM386 (U38) have the +9V at the pin 6? This is the amplifier for the internal speaker.
But I see dead LM386 only when reversed polority psu used...

Online Zozosoft

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Re: Enterprise does not power on anymore
« Reply #29 on: 2015.December.18. 22:07:32 »
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).

I guess contact problem somewhere at the power input, probably on the +9V lines. Problem with PSU input socket. Problem with 7805 ICs solderings, or cracked pins of these. (These are problems what I already found in some machines.)
« Last Edit: 2015.December.18. 22:12:57 by Zozosoft »