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Author Topic: Enterprise does not power on anymore (Read 21174 times)

Offline endi

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Re: Enterprise does not power on anymore
« Reply #45 on: 2015.December.19. 20:00:30 »
live news
saving the life of a dangered species :)
Vigyázat! Szektás vagyok! :)

Offline IstvanV

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Re: Enterprise does not power on anymore
« Reply #46 on: 2015.December.19. 20:13:15 »
The picture does not show characters but if you look good it seem that they are there..

What I meant is that even if the lines were shifted horizontally, it would not be possible to fix the display, which suggests it is not just a monitor issue. This can be clearly seen on the EXOS memory test picture. So, there is a problem with the (digital) output of the NICK chip.

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« Last Edit: 2015.December.19. 20:16:32 by IstvanV »

Offline Zozosoft

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Re: Enterprise does not power on anymore
« Reply #47 on: 2015.December.19. 20:45:54 »
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?
Firstly the Nick clock (B29 pin on the expansion port), the ideal freq are 14237536.27 Hz. Some diferrence are possible, it is can be adjusted with screw near to the power led. Need a stable signal.
HSYNC and VSYNC are available on the monitor connector and also on expansion port. These are 15611.33 Hz and 50.0363 Hz

Offline edoz

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Re: Enterprise does not power on anymore
« Reply #48 on: 2015.December.19. 21:06:21 »
What I meant is that even if the lines were shifted horizontally, it would not be possible to fix the display, which suggests it is not just a monitor issue. This can be clearly seen on the EXOS memory test picture. So, there is a problem with the (digital) output of the NICK chip.

(Attachment Link)

(Attachment Link)

Ok. It seems indeed something horizontal .. the thing is how longer the machine is on how better the quality for the picture gets.



Have fun with the Z80!

Offline edoz

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Re: Enterprise does not power on anymore
« Reply #49 on: 2015.December.19. 21:35:38 »
Firstly the Nick clock (B29 pin on the expansion port), the ideal freq are 14237536.27 Hz. Some diferrence are possible, it is can be adjusted with screw near to the power led. Need a stable signal.
HSYNC and VSYNC are available on the monitor connector and also on expansion port. These are 15611.33 Hz and 50.0363 Hz

Ok thanks. I will try if i can borrow a scope. Still the question if i can fix it (even with scope)
Let's see. I already glad that it does something. That means (i hope) that it could be fixed in the end.
Have fun with the Z80!

Offline Ep128

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Re: Enterprise does not power on anymore
« Reply #50 on: 2015.December.19. 23:15:14 »
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 :)

Internal checksum error...?

Offline BruceTanner

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Re: Enterprise does not power on anymore
« Reply #51 on: 2015.December.20. 00:43:39 »
As the initial symptoms were completely dead, it is worth going over the EP circuit board while powered on & gently tapping components with the insulated handle of a screwdriver to see if anything changes the screen display (makes it flicker or go off etc).

If it reliably gets better as it warms up you need to get yourself some component freezer spray. Then spray each component in the video circuit one at a time until it makes a difference. Maybe it will be the Nick chip but also it may be a resistor, capacitor or transistor, they are 30 years old after all.

Offline Zozosoft

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Re: Enterprise does not power on anymore
« Reply #52 on: 2015.December.20. 12:06:57 »
Ok. It seems indeed something horizontal .. the thing is how longer the machine is on how better the quality for the picture gets.
Once I see something similar what is on your latest photo.
What will happen if you try fine adjust Nick clock with L2 (it is left at the power LED)?

Offline IstvanV

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Re: Enterprise does not power on anymore
« Reply #53 on: 2015.December.20. 12:37:40 »
If the clock generator for the NICK works correctly, then there are exactly 284 cycles of the 4433618.75 Hz PAL color subcarrier frequency per line. Or, in other words, the ratio between the NICK clock and the PAL frequency is 228 / 71.

Offline zerodefect

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Re: Enterprise does not power on anymore
« Reply #54 on: 2015.December.20. 14:34:23 »
As Bruce said worth to check the solder points of the normally warm components (ICs, voltage regulator, etc.). The continuous warming-cooling tends to break the solder points of the component pins during the years which is invisible but a simple resoldering enough to fix them. If this not helps the another suspicious parts are the electrolyte capacitors which are drying out slowly and cause several problems especially near to the voltage regulator. I have already replaced many of them in my EP to prevent these problems.