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

[Tim Fadden]

-------- Forwarded Message --------
Subject: 	Re: [Coco] Fwd: Re: Disto Super II controller repair
Date: 	Thu, 1 Jun 2017 20:13:38 -0400
From: 	Bruce W. Calkins <brucewcalkins at charter.net>
To: 	Tim Fadden <t.fadden at cox.net>



I have not had to go any deeper into disk controller repair. However 
given the symptoms and that disk head movement signals for both 
directions go through the 7416/7406s, double check your repair and try 
another pair of chips?  Tony did publish a set of schematics for most of 
his products, however there were a number of "inaccuracies."  I will 
look in my files and try to find it.

That's a possibility, like it's getting the signal to go one way, but 
not the other........  I have the schematics, although none of them are 
exactly the same as my board.  That part of it is the same though.  If I 
can figure it out! ha ha ha


Bruce W.



On 06/01/2017 07:52 PM, Tim Fadden wrote:
> Bruce,
>
> Thanks for the suggestion of the  7416 chips.  I went ahead and got a 
> few of them, and replaced them with sockets.
>
> Now after executing the dskini command, the head steps through all the 
> tracks.  That is an improvement!
>
> Unfortunately after that it ends up giving an IO error.  On a good 
> dskini, with another controller, you can hear the heads return back to 
> track 0, and then steps for a while and completes.  On the Disto, I 
> don't hear the  movement back to track 0. (if that is actually what it 
> is doing).
>
> Not sure if it is not writing, or not reading, or something else is 
> going on.
>
> I am going to try a different ROM, in case for some reason that got 
> munged up.
>
> Any more suggestions?
>
> Thanks,
> Tim
>
> On 5/30/2017 3:10 PM, Bruce W. Calkins wrote:
>> 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.
>>>>
>>>
>>
>>
>
> -- 
> Tim Fadden
> "Hey Schmidt, don't forget about the six P's.
> Proper Preparation Prevents Piss-Poor Performance!"