Enterprise Forever

:UK => Hardware => Maintenance => Topic started by: edoz on 2015.December.18. 14:46:37

Title: Enterprise does not power on anymore
Post by: edoz on 2015.December.18. 14:46:37
Dear All. I have a problem. My Enterprise machine does not power up anymore :( I have only one machine .. and for me this is a bad thing as i cannot test SymbOS applications anymore on the real hardware. I have no idea what is going on.


Maybe someone can help me. I have no idea why. The machine was just on my desk all the time without any troubles.

The problem:

If i put the power plug inside the enterprise nothing happens. The RED LED is burning but i have no output picture on my monitor.
Normally you can hear the keyboard sound after a while if you press a key but this is not happening. I only have a black screen on the monitor and that's it. if i power on the system i hear a small 'click' from the speaker. (but that is normal i think)

Maybe.. but I'm not sure anymore i have inserted the monitor cable the wrong way (up side down) But I'm not sure if this can harm the machine. Anyway i think it as it could be that i did it but because i can't remember it anymore I notice it here, as maybe i did it ;)

Other thing is that i did a (volt) measurement on the adapter, which gives me a -12,2 output. On the adapter it is saying that it is 9.5 V so for me this is a bit strange. But I'm not sure what + and - is. (so it could be just +12,2) I have the feeling that the power plug inside part is the - and the outside mantel is the + ?. (But you cannot see it on the adapter)

Other thing is (I'm not an electronic expert) i have this BEEP sound on my multimeter to see if there is a connection between 2 points. If i power off the power adapter and i put  the + and - on the  + and - of the the powerplug it beeps ? (that is not good not?) So maybe i can replace the adapter with an other one but i need to be sure before doing that what is + and what is -

Do you have any suggestions?
 
Title: Re: Enterprise does not power on anymore
Post by: Zozosoft on 2015.December.18. 15:05:19
The inner are the negative on the power plug. Higher voltage without load are normal.

The monitor are old CRT or modern LCD? (Modern monitors don't display the broken picture, then you can't see the some lifesign.)

If I remember right you have a turbo machine. Change the CPU speed change anything?

Are you expert in electronics?
Title: Re: Enterprise does not power on anymore
Post by: Zozosoft on 2015.December.18. 15:07:46
And do you have any external expansion (EXDOS card, SD interface, etc). If yes then try to remove these.
Title: Re: Enterprise does not power on anymore
Post by: edoz on 2015.December.18. 15:14:09
HI Zozosoft!

No i use this old Philips CRT monitor (CM8833). But is shows nothing. Indeed i have the turbo inside. Switching between CPU speed those not do anything. No I'm not an hardware expert. But i can do some measurements with my multimeter.

Is there something else i can measure ? I have this digital multimeter fx-99mx.

So if i understand you right it seems that the power supply works fine then.

But normally you must have sound from the keyboard not? I have the SD card which i removed also. But that doesn't do anything unfortunately.
Title: Re: Enterprise does not power on anymore
Post by: edoz on 2015.December.18. 15:28:11
if i measure the voltage wile the machine is plugged and running it is indeed 9,34 V
Title: Re: Enterprise does not power on anymore
Post by: Zozosoft on 2015.December.18. 15:29:34
No i use this old Philips CRT monitor (CM8833). But is shows nothing.
Right input selected? :-)
And the monitor cable now in the right position?

At the most of time when Enterprise not starting, the Nick display some random screen garbage on the screen.
The totaly nothing sound very bad :cry:


Quote
Is there something else i can measure ?
Check the +5V at the joystick ports and at the cartridge socket. +12V at the monitor connector (mode switch signal).
Do it carefully, don't short circuit anything with the multimeter probes.
Title: Re: Enterprise does not power on anymore
Post by: edoz on 2015.December.18. 15:35:35
No. i selected the right input on the monitor. So i'm sure about that..

I'm not a hardware expert but i can  build in a 7 MHZ kit inside my MSX. I can solder a bit if there is a schematic for it ;)
And i can do some measurements. I will do it carefully.

Between Which PINS i must measure ? Could you give me some hint on that ?
Title: Re: Enterprise does not power on anymore
Post by: edoz on 2015.December.18. 15:38:35
BDW: You always have this sound from the keyboard not ?? (even if i have no display)
Title: Re: Enterprise does not power on anymore
Post by: edoz on 2015.December.18. 15:45:15
I have on the Controlports 1 and 2, (5V between pin 1 and 2) ( if you look from the back of the machine and it's about the pins on the top)

I have also on the Videoport 12V between pin 2 and 6 from top looked from the back.
Title: Re: Enterprise does not power on anymore
Post by: Zozosoft on 2015.December.18. 15:51:08
Enterprise pinouts. (http://enterprise.iko.hu/pinouts.htm)
Title: Re: Enterprise does not power on anymore
Post by: Zozosoft on 2015.December.18. 15:54:20
Normally you can hear the keyboard sound after a while if you press a key but this is not happening.
Yes, normally you can hear the key click.
Title: Re: Enterprise does not power on anymore
Post by: endi on 2015.December.18. 15:59:43
Yes, normally you can hear the key click.

if wp or basic or exdos etc started
Title: Re: Enterprise does not power on anymore
Post by: Zozosoft on 2015.December.18. 16:00:44
And i can do some measurements. I will do it carefully.
Try to measure the RESET pin on the system bus. Normaly it is on +5V, and pressing reset make a 0V pulse.
If it is on constatly 0V then very bad news, it is means the Dave not running :-(

More measurement need a scope.
Title: Re: Enterprise does not power on anymore
Post by: edoz on 2015.December.18. 16:01:08
I don't get it . I was just do measurements and spontaneously the Enterprise is STARTING!!
How good that be?!
Title: Re: Enterprise does not power on anymore
Post by: Zozosoft on 2015.December.18. 16:01:49
if wp or basic or exdos etc started
First key click at the ENTERPRISE screen! :-)
Title: Re: Enterprise does not power on anymore
Post by: endi 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 :)
Title: Re: Enterprise does not power on anymore
Post by: edoz 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..
Title: Re: Enterprise does not power on anymore
Post by: edoz 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 ?
Title: Re: Enterprise does not power on anymore
Post by: gflorez 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. 
Title: Re: Enterprise does not power on anymore
Post by: Zozosoft 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.
Title: Re: Enterprise does not power on anymore
Post by: edoz 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?
Title: Re: Enterprise does not power on anymore
Post by: Zozosoft 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.
Title: Re: Enterprise does not power on anymore
Post by: edoz 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?
Title: Re: Enterprise does not power on anymore
Post by: Zozosoft 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. (http://gafz.enterpriseforever.com/Galery/Alapgep/Picture/ISSUE6-6.jpg)

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?
Title: Re: Enterprise does not power on anymore
Post by: edoz on 2015.December.18. 17:05:20
Ok .. here the picture of the mini break. it is very very small

(http://i68.tinypic.com/2ps1w6a.png)


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

(http://i63.tinypic.com/2iu9ef6.png)


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)

(http://i68.tinypic.com/156vkgj.png)
Title: Re: Enterprise does not power on anymore
Post by: edoz on 2015.December.18. 17:13:54
Hmm no the sound is from the speaker. it is just background noise.
Title: Re: Enterprise does not power on anymore
Post by: IstvanV 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.
Title: Re: Enterprise does not power on anymore
Post by: Zozosoft 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.
Title: Re: Enterprise does not power on anymore
Post by: Zozosoft 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...
Title: Re: Enterprise does not power on anymore
Post by: Zozosoft 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.)
Title: Re: Enterprise does not power on anymore
Post by: edoz 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 ?

Title: Re: Enterprise does not power on anymore
Post by: edoz 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
Title: Re: Enterprise does not power on anymore
Post by: Zozosoft on 2015.December.19. 08:14:12
Yellow point the GND pins, red are the +5V pins:
[attach=1]
Title: Re: Enterprise does not power on anymore
Post by: Zozosoft 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.
Title: Re: Enterprise does not power on anymore
Post by: edoz 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.


(http://i63.tinypic.com/2j624k8.jpg)

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 ;)

(http://i68.tinypic.com/15wexs4.jpg)

(http://i64.tinypic.com/2wea2cy.jpg)

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)
Title: Re: Enterprise does not power on anymore
Post by: Zozosoft 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. (http://gafz.enterpriseforever.com/Galery/Alapgep/Picture/ISSUE5-4.jpg))

Title: Re: Enterprise does not power on anymore
Post by: edoz 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. (http://gafz.enterpriseforever.com/Galery/Alapgep/Picture/ISSUE5-4.jpg))

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?
Title: Re: Enterprise does not power on anymore
Post by: Zozosoft 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:
Title: Re: Enterprise does not power on anymore
Post by: edoz on 2015.December.19. 13:22:08
Yes the display output is now always like this. Is there something else I can check?
Title: Re: Enterprise does not power on anymore
Post by: Zozosoft 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.
Title: Re: Enterprise does not power on anymore
Post by: edoz on 2015.December.19. 19:12:02
Yes it works! .. seems that i now only have this strange video output somehow.
Title: Re: Enterprise does not power on anymore
Post by: IstvanV 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.
Title: Re: Enterprise does not power on anymore
Post by: Zozosoft 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.
Title: Re: Enterprise does not power on anymore
Post by: edoz 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..
Title: Re: Enterprise does not power on anymore
Post by: edoz 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?
Title: Re: Enterprise does not power on anymore
Post by: endi on 2015.December.19. 20:00:30
live news
saving the life of a dangered species :)
Title: Re: Enterprise does not power on anymore
Post by: IstvanV 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.

[attachthumb=1]

[attachthumb=2]
Title: Re: Enterprise does not power on anymore
Post by: Zozosoft 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
Title: Re: Enterprise does not power on anymore
Post by: edoz 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.


(http://i67.tinypic.com/10fylqq.jpg)
(http://i66.tinypic.com/294m1br.jpg)
Title: Re: Enterprise does not power on anymore
Post by: edoz 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.
Title: Re: Enterprise does not power on anymore
Post by: Ep128 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...?
Title: Re: Enterprise does not power on anymore
Post by: BruceTanner 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.
Title: Re: Enterprise does not power on anymore
Post by: Zozosoft 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)?
Title: Re: Enterprise does not power on anymore
Post by: IstvanV 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.
Title: Re: Enterprise does not power on anymore
Post by: zerodefect 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.