[Coco] Fwd: Re: Disto Super II controller repair

[Bruce W. Calkins]

The 7406 tolerates higher voltages.  The other specifications are well 
within the needs for this circuit.  This results in a part that probably 
will never need replacing.

If I remember correctly, these chips pass the signals that move the 
drive head among other things.  If the head does not move, the disk does 
not get formated.

Bruce W.



On 05/30/2017 01:02 PM, Tim Fadden wrote:
> Bruce,
>
> Ok, I got it stable now, by replacing the ROM socket.
>
> I get no head movement when doing a format, so perhaps the 7416 like 
> you say.  Worth a shot.
>
> So, how would one go about checking them, besides just replacing them?
>
> And, I was wondering, whats the difference between the 7416, and 7406. 
> Both are available.
>
> Cheers.
>
> On 5/29/2017 8:04 PM, Bruce W. Calkins wrote:
>>
>>
>>
>> -------- Forwarded Message --------
>> Subject:     Re: [Coco] Disto Super II controller repair
>> Date:     Mon, 29 May 2017 22:01:24 -0400
>> From:     Bruce W. Calkins <brucewcalkins at charter.net>
>> To:     Camillus Blockx <camillus.b.58 at gmail.com>
>>
>>
>>
>> A common failure on the Tandy controllers was one or both 7416 chips on
>> the output side.  Removing the chips and socketing a pair of 7406 chips
>> was the cure.
>>
>> I see there are two 7416 chips on the output side of my Super Controller
>> II.  I would suggest starting with checking them.
>>
>> Bruce W.
>>
>