disk II broken due to mis connection on controller

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disk II broken due to mis connection on controller

I was wrong when I connected my disk II to the controller board

row 2-4-6...20 was connected on row 1-3-5...19

any idea of way may have burn ?

the 74LS125 is dead, exploded, I changed it

then engine is turning, and I hear a bump, so I guess the stepper is working

connection realized with my error
gnd 1 2 stepper 0 ok
gnd 3 4 stepper 1 ok
gnd 5 6 stepper 2 ok
gnd 7 8 stepper 3 ok
-12 9 10 wrreq burnt ?
+5 11 12 +5 ok
+12 13 14 drven burnt ?
+12 15 16 rddata burnt ?
+12 17 18 wrdata burnt ?
+12 19 20 wrprot burnt ?

any idea of the conponent that burnt in this case ?

thanks

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Re: disk II broken due to mis connection on controller

Hello dvador,
i gave warning in my pages to pay attention to the pin 1 at the two ends of the drivecable
at controller and at drive side......
in case of turning around the cable the most common damages happen at the analog board of the disk II.
If you are lucky, only the LS215 and the ULN2003 have been damaged ( like in most cases ) .
In bad case also the MC3470 and the CA3146 are damaged.
In normal conditions the active chips on the Motor Control Board are not damaged because the IC´s
at the Analogboard get killed much faster...
If your drive has the colored cable it´s recommended to mark the side with connection to pin 1 to avoid
mistakes in the future....
sincerely speedyG

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Re: disk II broken due to mis connection on controller

Hi speedyG

I'm less young than I was when I was using an Apple II (I should have removed my glasses)

the engine turn so I hope it is not damaged...
it bump so I hope the stepper is ok too
I replaced the 74LS125 and ULN2003... same result (the disk turn, I hear the bump)
I ordered MC3470AP and CA3146...

thanks

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Re: disk II broken due to mis connection on controller

All 4 chips changed same result

floppy disk spinning,
I hear the bump so the stepper seems to work

and nothing else

any idea ?

thanks

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Re: disk II broken due to mis connection on controller

Hello dvador,
n that case it seems that also something has been killed on the interface itself too...
Can you post a good picture with high resolution from the diskinterfacecard ( at least 4 MegPixel,
good focus and good light )and probably also from the analog board of the drive ?
Do you have a chance to test the "repaired" drive at another diskcontroller
( taking of course precautions not to twist cable again ) ?
How much time has the drive been connected wrong way around to the powered on controller ?
Just to give an idea:
wrong connected cable kills at the analogboard:
within 3 to 4 seconds the LS125 and the ULN2003
within 10 to 15 secondes the CA3146
and within 20 to 25 seconds till it kills the MC3470.....
depending to the controller used parts of the controller may get killed within 30 seconds...
if its the "standard Apple II Diskcontroller there are 2 versions:
the one with 2 small transistors or
the one with 2 larger mediumsize transistors ( permitting higher power consumption )
the first can get damaged within 25 seconds and the second kind might get damaged at the transistors
few less than a minute....
that is without the time requested to kill a logicchip at the "standard" Disk II controller....
other variations of disk controllers may vary in "survival"-time depending to the kind
of logic on board and the question if chips have been used with "open collector"-outputs of the logicchips.
Therefor the inquiry to recognize what kind of controller has been used ( and maybe see a damage )
and the request for picture of the Analog Board of the drive....
sometimes also there damages are visible...

speedyG

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Re: disk II broken due to mis connection on controller

it was connected probably for less than 2 secondes the time to switch on / switch off
I switched off when I heard the explosion of the 74LS125 (a part was missing)

In fact I repaired the analogic board long ago... only the 74LS125 was broken
but I have another problem

the motor has a hard spot if I turn the rotor of then motor manually, (from under)
then floppy starts to work normally

I had this problem before the wrong connection...

apparently once unblocked it works for several day, but if I stop using it for a few days
the motor becomes stuck again

is there a procedure to solve this problem ? or do I need to fine another motor ?

thanks

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Re: disk II broken due to mis connection on controller

Hello dvador,
just for confimation... there are 2 motors.... :
the spinning motor ( with the belt ) and the positioning motor ( with the white positioning disk )......
which are you talking about ?
It seems you are talking about the positioning motor, but i prefer to get confirmation...
speedyG

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Re: disk II broken due to mis connection on controller

I'm talking about the spinning motor get stuck from time to time
works after having turned the rotor manually

the stepper motor is working perfectly

thanks

speedyG's picture
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Re: disk II broken due to mis connection on controller

Hello dvador,

there are several different reasons optional for this behaviour:

maybe the drivemotorbelt has been replaced with a wrong belt which is slightly to tight....

you can check this, by checking if the motor starts up normal after blocking just by removing the transmissionbelt.

Second there might be a lockup in the electronics:

check at the motorcontrolloerboard at the rear of the drive for the
motorcontrol IC and there at pin 7 - there should be 10,4 Volt.
At the emiter of the Motor control transistor Q4 there should be 6 Volt present.

Inside of the motor ther are several blocks of wirewindings.
( covering the stantors )
they should all have the same resistance. The resistance of the coilwindings at the stantor can be measured
between the red and blue wire
or
the green and yellow wires.
(and can be measured in the different positions of the motor.)
It is possible - that while the cable was twisted around and wrong voltage of 12 Volt went along the winding without correct grounding and therefor standing motor - that one of these internal stantor coils has been damaged by overheating and melting of the wirecovering and thereby producing a internal schortcut in the stantor winding resulting to large difference in resistance of the coils.... in such case the motor will allways remain in same position in standing status, while in other position the motor will start spinning. This will also mean that the motor is not working on all stantors
( compareable to a car motor that is not working on 8 cylinders but only with 7 cylinders while one cylinder in not operatable and car always blocking if the damaged cylinder is determined to start up )... In such a case the only solution will be to replace the drivespinningmotor.

sincerely speedyG

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Re: disk II broken due to mis connection on controller

thanks for your advices, I'll check the drive next week end

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