Closed 1541 newtronics drive head or ALPS drive mechanisim

rheffera

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Hi

I'm looking for a replacement head for a newtronics disk drive for the 1541. Alternatively, I would also be interested in an entire ALPS mechanism for a 1541.
 
That is true... That trick only makes a poorly working drive though, I think.

Most of my heads are not open, but very high (15k) resistance on one side of the coil or the other, so I disconnect that side of the coil from the board and replace with 12ohm resistor to the center tap.

It can then read, but not that well... I think you are only getting half the signal strength, so many errors and some fast loaders don't work well at all...
 
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That is true... That trick only makes a poorly working drive though, I think..

The "jumper" or the "12 Ohm" that replace the missing half head has to be used only on the missing half head, only for a not-working head.

Most of my heads are not open, but very high (15k) resistance on one side of the coil or the other, so I disconnect that side of the coil from the board and replace with 12ohm resistor to the center tap.

You read 15k because on the backside of the head is placed a diode (on the erasing coil) and a 15k resistor on reading coils terminals, so if a reading coil is open you will read the resistor: it's normal.
I suggest to don't disconnect the (15k) open side of the head, and to put on it a jumper, or a 12...15 Ohm resistor.

It can then read, but not that well... I think you are only getting half the signal strength, so many errors and some fast loaders don't work well at all...

An reading half coil produce half voltage that feed the analogic chain that end with a voltage level comparator that produce a logic level.
Normally this level drop (6dB) is not critical so I consider strange that some disk could be loaded or not for this reason, maybe that the physical disk has not an identical alignment to the reading mechanism, so the level is already dropped by this misalignment....
I'm curious to try it with my oscilloscope .... I have to download a .D64 image of a disk that has this behavior with evidence, could you suggest some titles?

Please, use this thread:
https://www.amibay.com/showthread.p...41(C)-with-magnetic-head-open-how-it-can-work
 
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