1050 "repeat" spin up

[Guest]

Weird one this, and - if it's been posted elsewhere, apologies - i can't find a similar thread.

This is a stock 1050 in immaculate condition.

 

Ok - important (i think):

This symptom manifests itself regardless of whether the 1050 is

1] connected to Atari XL

2] booted with or without option

3] powered-up unconnected to Atari XL

NB - when connected there is no "boot error"

 

now the dumb-ass description of the symptoms

 

power-up

drive spins for 2 seconds...stops for 2 seconds...drive spins for 2 seconds...stops for 2 seconds...drive spins for 2 seconds...stops for 2 seconds...drive spins for 2 seconds...stops for 2 seconds...drive spins for 2 seconds...stops for 2 seconds...drive spins for 2 seconds...stops for 2 seconds...drive spins for 2 seconds...stops for 2 seconds...drive spins for 2 seconds...stops for 2 seconds...ad nauseum (or until i power off)

 

any ideas at all would be appreciated

Edited October 19, 2016 by Guest

[+Stephen]

I believe that is a symptom of it failing the quick self-test it does on powerup. If any of the large ICs are socketed, you can try pulling & re-inserting.

[Guest]

cheers, will do

 

ok, update

all socketed ICs swapped for known good ICs.

result: no change

Edited October 19, 2016 by Guest

[1050]

At this point it would be nice to see a list of the chips you

didn't exchange with known good ones.

[+Stephen]

I checked the FSM and SAMS Computer Facts, and didn't see anything which directly mentioned this particular issue.

[Guest]

all of the main 5ICs across the middle of the board

 

R6532, CPU, PROM, FDC etc

[Rybags]

With the powerup test and sometimes in general use, what is considered a fatal failure by the firmware will jump to a never-ending sequence where the motor and busy light alternate on/off every 2 seconds.

That's all, they didn't bother to make it give any feedback as to the reason, there's about 10 different circumstances it'll decide to do it including a failed Ram test on powerup.

 

But at least the flashing means the 6507 and Rom are good to the point where that can happen.

[+kheller2]

Odd.. this is usually an issue with the 6532, although maybe the RAM is bad. But if you swapped ALL the chips under the shield its time to look for power problems.

[1050]

Perhaps your donor drive has a different OS Rom jumper scheme going? These would be the white

resistors at back end of the eprom/PROM. It can take either. It could be that you put a

PROM in where an eprom should have been and you are thinking you have tested it with a good

OS rom when you really haven't as yet.

 

Parts swapping to find the bad one does work both ways, what happens on your good drive

for example?

Edited October 20, 2016 by 1050

[+tf_hh]

power-up

drive spins for 2 seconds...stops for 2 seconds...drive spins for 2 seconds...stops for 2 seconds...drive spins for 2 seconds...stops for 2 seconds...drive spins for 2 seconds...stops for 2 seconds...drive spins for 2 seconds...stops for 2 seconds...drive spins for 2 seconds...stops for 2 seconds...drive spins for 2 seconds...stops for 2 seconds...drive spins for 2 seconds...stops for 2 seconds...ad nauseum (or until i power off)

 

Do you know if the drive was working before? Or it is a eBay purchase or something like that? If you´re not sure if this drive ever works fine, then check the settings of the JP1...JP4 bridges. You will find two settings, one for MASK-ROM and the other for an EPROM. Settings are described in the SAMs computerfacts or the Jerzy schematics. Check if the setting is right depending on the ROM- or EPROM-type the drive using.

 

This behavior means mostly that the RESET routine can´t use the 6502 stack ($0100-$01FF, in the 1050 circuitry only $0180-$01FF) properly. Mostly the 6810 SRAM is defect, do you really change all chips? Also a bad RIOT (6532) with one or more defect portbits can force this issue.

 

When you can exclude all that, next steps need an oszilloscope.

 

Good luck, Jurgen

Edited October 20, 2016 by tf_hh

[Guest]

As it's an ebay job - these are the "out of the packaging" symptoms.

 

I've swapped out TWO complete sets of ALL of the main bank of ICs - as described above.

I have also put the "non-working drive's" ICs individually and together into known working drive and all worked fine.

 

will now look at Jurgen's/1050s suggestions

 

footnote:

i know most will have taken this as read...but just in case:

there is NO drive head movement at all - not even a track 0 seek?

 

does that change anyone's views?

Edited October 20, 2016 by Guest

[Rybags]

There's earlier test steps before seek is attempted, that could indicate it's failed at that point but like I said earlier, it's a 1 error signal for all conditions which just makes diagnosing harder.

[1050]

With this rom working in your donor drive, you have confirmed that your jumpers are the

same, so no further worries there.

 

Not sure about views issue, we are just approaching the problem with what we think is

the most common things to go wrong combined with the fastest way to find out.

 

You seem to have a unique one alright. I've not seen a similar case at all.

 

The usual tack to take then would be as kheller2 suggests, check for proper voltages.

But you have working 12 volt for the disk motor and 5 volts for the OS stop motor and

restart motor sequence, so I assume you are good. Best to check though. What voltages

do you find on the legs of the two voltage regulators Q7, Q8 mounted to the rear of the

heat sink?

 

I suspect the stepper motor is not functioning. Can you move the head sled with power

off? Does it become noticeably more difficult to move with power on because it should

pretty much lock down right where it is. It could be plugged in backwards?

I have two red wires on the front end which are pins 5 and 6, both are power

in.

 

On the unplugged drive stepper motor, J15 cable, pin 1 to 5,6 should be 33.5 ohm,

same for pin 3 to 5,6. Pin 2 to 5,6 should be 33 ohm, and same for pin 4 to 5,6.

 

Coincidence has it that the junker I use for handy reference has a crack in L6 which

is in the power supply path for pins 5 & 6 of J15, just noticed this too. It has

many other issues.

[re-atari]

As it's an ebay job - these are the "out of the packaging" symptoms.

 

I've swapped out TWO complete sets of ALL of the main bank of ICs - as described above.

I have also put the "non-working drive's" ICs individually and together into known working drive and all worked fine.

 

will now look at Jurgen's/1050s suggestions

 

footnote:

i know most will have taken this as read...but just in case:

there is NO drive head movement at all - not even a track 0 seek?

Martin,

 

I've seen this behavior once, turned out to be a defective 6532 at that occasion. As you already ruled this one out as the culprit, I'm afraid no head movement does indeed sound like a malfunctioning stepper motor or its driver electronics on the PCB (between the 6532 and the large electrolytic caps).

 

I couldn't find it in your posts above, but did you already swap the drive mech with the one in the working 1050? That will at least give you an indication if the problem is in the drive mech or the driver electronics.

 

re-atari

Edited October 21, 2016 by re-atari

[DavidMil]

Did I understand correctly that you also have a good 1050? If so, have you swapped the transports of both drives to see if the problem moved?

This is a good, quick way to verify that the motors are working.

 

DavidMil

 

[Guest]

thanks for the last two posts - it's certainly starting to look like the motor

will be onto that tomorrow