new PSU - 1581 hangs still

[MIRKOSOFT]

Hi!

I have big problem. I was working on my C128 and 64HDD with connected 1581 drive.
All was ok. But after one turn off/on computer and drive:
1581 starts ok, but at BOOT sequence hangs, access to 64HDD was not available.

So, I press STOP+RESTORE and try to write DIRECTORY - 1581 hangs, LED is lighting and computer hangs too.
I tried also access 64HDD, all devices hangs.
I tried to connect XE cable direct to computer, access to 64HDD works properly.
I tried to connect 1581 to my C128DCR - computer hangs at boot and couldn't work. When I disconnected 1581, C128DCR works properly...

So, now it seems like problem with
serial bus
or
1581 only

But if 1581 only why can't access 64HDD?
So, I ordered at Tinchens-online shop 1541-II PSU (which is compatible with 1581 PSU).

Today arrived my order, I tried to plug-in and after test above written failure...

1581 HANGS STILL - NOTHING WAS SOLVED, HOW TO AGAIN?

Have I to replace 1581JiffyDOS to original KERNAL?

Thanks for every reply!

Miro

[MIRKOSOFT]

So, I tried to replace JiffyDOS with original KERNAL 3 times - no solved.

Drive always make the same thing - at power on works like normally, when I turn on computer hangs...

Access to 64HDD is ok, but only if is XE-cable connected to computer directly.

I tried if is any wire not pulled out, nothing found...

So what now?

Thanks for every help.

Miro

[LokalHorst]

to track down the error you might follow a strategy which excludes one possibility after the other.
Begin with disconnecting all devices, except the '81. As I understood your description the drive performs it's internal self-test without failure, to exclude a defective cable (the cheap ones may not even connect all lines - I've got some which didn't connect SRQ) replace with a spare one, or one you know of working flawlessly. Next power-on the C128 & drive, then goto the ML-Monitor and request an error status with @[dev#] this does not access the disk, but transfers data over the IEC-bus.
If you retrieve an error status "74, CBM DOS..." the ser. communtication parts of the drive (8520/6526 & 74LS06/07) are ok (hopefully).
If the former was ok, try a cmd which accesses the disk (i.e. dir - @[dev#],$ ) - if it hangs then, it's most probably caused by a problem with the power supply. During the motor-start phase the drive mechanic draws a higher current than normally, this can cause a voltage drop and a subsequent crash or lockup of the CPU. I solved this sort of irregularity with a new wiring of the drives power cord straight to the power plugin-socket plus an additional capacitor (4700uF) between +5 and ground.

If the former doesn't work (C128 hangs), then most probably one ore more of the IC's connecting to the IEC bus are defective, you can test in power-off state with a multimeter if one of the lines is short to ground, then look up the schematic (attached) which parts connect to which line.

[MIRKOSOFT]

So, I tried to start computer with holding down STOP key.
It starts to ML monitor. I entered @8
First: hangs, drive does nothing
2nd: I/O ERROR #2, computer hangs not, drive does nothing
3rd: hangs, drive does nothing


What it seems?


Thanks for every reply.


Miro

[LokalHorst]

If the cables are ok and the c128 communicates with other IEC devices, then you have to check for defective parts inside the drive. If your're lucky only a 74ls06/74ls07/74ls14 needs to be replaced (most common).
See the schematic I posted above which shows the IC's connected to the IEC socket on the right side.

Maybe you're able to track down which line is not ok -
enter the ML-mon. again as you did before but this time enter no drive cmd.
type in:
>fdd00
the first value shown should be 'C7' if not, then '47' means the data line is at fault, or if the value is '87' the clock line is not ok.
If the value was 'C7' modify the first byte to 'CF' clear the rest of the line with ESC Q - the new read value should be '4F' this test was fo the ATN line.

[MIRKOSOFT]

Need it soldering?


If are socketed it's not problem, I'll try to find new.
But soldering is for me big problem...


Miro

[MIRKOSOFT]

Now I see on scheme, they're not chips (good), need soldering (bad).


Please if you can, write to me types of spare which I need to buy.


Many many thanks.


Miro

[MIRKOSOFT]

C7 value is set to 97 (values after are FF 3F 00)
after modifying to CF is new value 0F


What seems this value?
Thanks.
Miro

[LokalHorst]

Then you have indentified the clock line as not ok - so see which parts are connected to that line. those 74ls06 74ls14 are cheap but you'll need someone to de-solder them for you if you don't have the skills.

[MIRKOSOFT]

74LS14 there are lot...
74LS06 none, only 7406, can you highlight for me that line on scheme? I'm in this anti-talent, so, where and which are wrong...
if you have for me patience, I'm sorry...
Many many many thanks.


Miro

[MIRKOSOFT]

in attachment is part of scheme - are there these? (red highlighted)

[MIRKOSOFT]

or the green and U9?

[LokalHorst]

7406 and 74ls06 are the same, the latter is 'low power shottky' (usually build in)
U9 and U12 has each 6 of those inverters shown in the schematic U12 is for the output and should be replaced first (74ls06)

[MIRKOSOFT]

"U9 and U12 has each 6 of those inverters"
don't understand: U9 has 6 inverters and U12 also?
so, I think I don't understand the scheme... there are shown only two spares... don't understand number 6?!?!

[LokalHorst]

look at the pin numbers, you'll find 6 x U9 and 6 x U12 (each IC has 14 pins 2 are not shown VCC - 14, GND - 7)

[MIRKOSOFT]

I did a picture of mainboard, are red-highlighted that?

[LokalHorst]

Yes, those are the parts. Replace U12 first and see if the drive is responsive again, if not replace U9 also. Maybe, as you already opened the drive, check if the CIA 8520 is seated correctly in it's socket.

[MIRKOSOFT]

My friend!


Every sockets were checked - all is on it's place (to be sure I pushed all).
Ok, only one thing is for me now not visible: YOUR NAME...


You helped to me more and more and I want to my project aceCommander128 (you know that you helps me again and again) give not only LokalHorst, but rather real name as coder... if you want...
btw. detokenizing BASIC I did easier, but your help was the right way...
If you'll need any SW or other, I'll do all to help you.
So, now, I want only know who LokalHorst is... :-)
Many many thanks.


Miro

[MIRKOSOFT]

Hi!


So, I was in shop, buy there 7406 (not 74LS06) and 74LS14N (not 74LS14) - is problem with these other marked spares? other types they haven't and seller say that's the same, is it truth?

[LokalHorst]

Yes, 7406 and 74LS06 have the same functionality, you can use it.
The same goes for the suffix N of the 74LS14 (specifying a temp. range or package - not important here).
If you replace those parts yourself take notice of their orientation, pin no. 1 is usually marked on the board, the IC's have a notch or other marker at the top of the package, where pin 1 is.

[MIRKOSOFT]

so e.g.:
|--U--|  <--- pin1 on top side?
|       |
|       |
|___|


Thank you.

[LokalHorst]

No, just the other way around (counter clockwise)

1|--U--|14
2|       |.
.|       |9
7|___|8