My new EII - some problems - need you help!

[Freddy]

Hi,

I bought an EII from switzerland, but I knew it was broken, but I thought I will try my best, especially as I got it for 500€ with 100 floppies and even with the original factroy box.
The seller assured me that only the front panel doesn't work, but after having received it today, there are a few small other things that don't work.

Nevertheless I'm quite happy, because I noticed that it has been upgraded and has a second floppy drive. It also has the memory board plus extension and the display works.

1) Actually the EII doesn't want to boot, because the floppy drives simply don't start to work. The display just says "Insert Disk". But the LEDs on the floppy drives light alternately.
2) The second thing is that the control panel doesn't work according to the seller, but the display itself does. I could imagine it's just a damaged cable...(?)

Do you know what could be the problem here?

Thanks for your help!
Freddy

[Elmbeatz]

If I was you, I'd reseat every chip and connector that you find inside, then switch it on again and check.

[sllaci]

Hello

What kind of floppy drives in it?
Possible misalignment of the replaced drive (jumpers)
Try only one "original" drive (ID0!! and termination)
It is possible that both floppy poor him!

If this does not help, then I think there are serious control problem.
The LCD, buttons and LEDs floppy and elsewhere are controlled. (CTC, PIO, SIO)

The LEDs light up?

Laszlo

[kdk]

And of course check your power supply. My EII was not making sound and the disk drive was not working, even thought the red LED would turn on.

It had a bad power supply -the voltages were too high. (Even with this, the the digital side of it was still working.)

I replaced the PSU with a modern unit and it works fine.

Kirk

[Freddy]

Hi,

after having reseated every single chip and every cable, nothing has changed.

I think I forgot to tell you that it fully worked before I got it shipped from switzerland apart from the control issue, but the seller said that loading disks worked flawlessly.

Basically I think the major issue is that the floppy drive motors don't start to do anything, but the LEDs light up alternately.

Any suggestions?

Thank you soo much!

[Freddy]

Hi!

I read a couple of threads in the meanwhile and I found out that a miscalibrated psu may cause problems. Accroding to the thread above (by hideawaystudios) I checked the voltages (DC).

Pin 1 (red): 16,2V
2 (yellow): 19,6V
3 (yellow): 19,5V
4 (green):14,6V
5 (green): 14,6V
6 (blue): 16,6V
7: unused
8 (black): ground(??)

These values look very strange to me as they differ so much from the ones written in the thread above. If they are wrong which calibrating screws to I have to turn and how do I have to proceed in general?

UPDATE: This guy seems/seemed to have exatly the same problem... http://launch.groups.yahoo.com/group/emulatorII-list/message/2959

Thank you very much for your help!!

[sllaci]

Hello

These values ​​are very bad.
The +5 V instead of so much destruction can be made ​​in many IC.
I claim a maximum of +5 V to +6 V.
The rest have not tried much bigger.
Most SN74xxx IC +7V or +8V over the burn.
Try to repair the power supply.

Laszlo

[FmK@77]

Hi Freddy,

I don't know anything about calibration screws. The capacitators on the psu are used to store energy and most likely one or more are faulty (leaky) and therefore pass higher voltages on the psu. You can feel on the capacitators if there really hot (faulty). When they are cold, most likely not operational anymore and needs replacement. You have to recap those on the psu in order to find out if the voltage has caused more damage to the chips on the mainboard etc.

Kind regards,
Frank

[sllaci]

Hello

Need me again measure the voltage!!!!
I do not think a good place to GND!
Look at this: http://eiiiforum.com/index.php?topic=370.0

GND: green cable: J101 pin 4-5

If +5 V instead of +19V, it would all board go in the bin.
All ICs have been destroyed.

Laszlo

[Freddy]

Hi,

thanks for your reply. I already suspected that this cannot be true, particularly because it would have fried every chip

Pin 1 (red): 1,6V
2 (yellow): 4,8V
3 (yellow): 4,8V
4 (green): 0V
5 (green): 0V
6 (blue): 0V
7: (unused): 15,05V
8 (black): -14,64V

Are these tolerances normal and fine or do I have to change something. If so, how?

Thank you!!!

Best regards,
Freddy

[sllaci]

Hello

It would be good to bring up +4.8! (+5.1)

PIN1 is not good! The good: 13.4V
This can be a major problem!
I do not think it can be set up:(
Increasingly possible categories that need to be improved

Careful!!!

+5V adjusted: R116 trimmer

+13.4V adjusted: R134 trimmer

You did not have the floppy drive type numbers!
They can be bad jumpers!

Laszlo

[Freddy]

Hi
thanks for your support!

After having read some troubleshooting pdfs (diagnostics, service manual) and guided by your advices I found out that the PIN 1 voltage is dramatically wrong and I could track the problem down even in the floppy drives. I guess it is a faulty capacitor or what do you think. If there was a short or an open circuit somewhere the machine would't work at all

[sllaci]

Hello

It is possible that only one capacitor.
Look at the diagram.
This schematic is very simple.
Measure the voltage at the input of the LM350:
Pinout:
http://www.ti.com/lit/ds/symlink/lm350-n.pdf
Must be greater than 13.4. (I think: 18-25V)

If not much, then proceed backwards.
Somewhere you will!
Replace all parts that have followed.
If the output of the transformer is good, you can pick out the first diode. (CR11?)
If so there is no voltage, the transformer is bad.

Laszlo

[Freddy]

Hi!

Good news!! (?)

I resoldered a couple of bad and old looking solder joints on the PSU. Then the voltage was suddenly 13,2V (pin 1 - black) again. I adjusted it via the the potentiometer and now it's 13,41V again.

Do you think it's a problem that the Pin 8 (black) displays only -14,64V instead of -15V; I simply cannot adjust it via the 4 potentiometers?

The floppy drives are now loading and working, but nevertheless the sampler still doesn't fully work. Now the display stucks at "This will take a while" and the floppy drives stop to operate after approximately. 20 sec. This does not change.


Thank you for your help!!!!

[kdk]

Maybe your boot disk is bad? Do you have another disk you can boot from?