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Atari 1050

JammyJules said:
I find this interesting and frustrating :

I removed a 47uf 16v cap, and I have 3 ways to test it.

1. Owon SPM6103 bench supply and multi meter reads : 58.13uf
2. TC1 Multi-function tester reads : 50.23uf, ESR 2.9 ohms
3. PEAK atlas ESR70 gold meter reads : 48.67uf, ESR 2.6 ohms

I wonder which is correct ?
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If your caps are Chinese generic, that could explain why you're now having deeper issues after recapping. I ordered one of those variety pack cases from Amazon and they were only good for the trash can. Like you, I had different readings on different meters, and in some cases never the same reading twice on the same meter. I have no idea what causes that. When I test a genuine Rubycon or Nichicon, it's the same solid reading across all testers.
 
Torch said:
If your caps are Chinese generic, that could explain why you're now having deeper issues after recapping. I ordered one of those variety pack cases from Amazon and they were only good for the trash can. Like you, I had different readings on different meters, and in some cases never the same reading twice on the same meter. I have no idea what causes that. When I test a genuine Rubycon or Nichicon, it's the same solid reading across all testers.
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These readings were from one of the original caps.

You are right though, I bought bulk kit which are probably Chinese to recap. I will gave a look for better makes, although I am not convinced it is a cap issue - as none of the ones I replaced read bad out of circuit.
 
Just as an aside, an AC "power supply" is probably just a chonky step-down transformer and some passive components for filtering/cleaning up any electrical noise.

I wouldn't be surprised at all if they had used a straightforward 12V AC step-down XFMR (10:1 winding ratio) and dropped 3V somehow or possibly an 18V AC step-down XFMR (7:1 winding ratio) with a center tap.

You could probably even build yourself a new one, but I guess there's no point if you have a readily available DC power supply. Most of hardware probably wants DC anyway.
 
Istarian said:
Just as an aside, an AC "power supply" is probably just a chonky step-down transformer and some passive components for filtering/cleaning up any electrical noise.

I wouldn't be surprised at all if they had used a straightforward 12V AC step-down XFMR (10:1 winding ratio) and dropped 3V somehow or possibly an 18V AC step-down XFMR (7:1 winding ratio) with a center tap.

You could probably even build yourself a new one, but I guess there's no point if you have a readily available DC power supply. Most of hardware probably wants DC anyway.
Click to expand...
The one supplied wasn't an original Atari branded supply, and to that the label with the output rating was removed.
 
JammyJules said:
Well intermittently I was seeing activity on the Rom CE pin with the original, now it it just stays high.
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Strange, test the replacement capacitors. Sorry if I can't respond as much right now, I'm working on the schematic for my homebrew.
 
xp0nentz said:
Strange, test the replacement capacitors. Sorry if I can't respond as much right now, I'm working on the schematic for my homebrew.
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Its midnight here in the UK, so I am not actually working on it right now. I did check each one before I fitted them.

I have this nagging feeling its something to do with the reset circuit. When I fixed a PET and a few C64's, the delay was obvious. The reset line on this appears to go near instantly high. I am going to bend the pin out tomorrow and manually feed it 5v after powering up - I think that should prove it or not?
 
JammyJules said:
Its midnight here in the UK, so I am not actually working on it right now. I did check each one before I fitted them.

I have this nagging feeling its something to do with the reset circuit. When I fixed a PET and a few C64's, the delay was obvious. The reset line on this appears to go near instantly high. I am going to bend the pin out tomorrow and manually feed it 5v after powering up - I think that should prove it or not?
Click to expand...
Make a reset button on a breadboard if you can.
 
ok - Now I don't think it is the reset circuit. I made up a lead with a 10k resistor. Connected the RES on the 6507 to 5v, and then grounded the pin for a second. Didn't change anything. Still no activity on address or datalines from the 6507.

Onwards and upwards as they say ..
 

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I have verified the rom to Atari 1050 vA.rom in my t48. I am now assuming the rom is ok.
 
Related tangent:
Note that it's possible to do some simple testing of an Atari 8-bit disk drive even without a bootable DOS disk.
I.E. it's possible to enter a short basic program that formats a disk and that reads/writes raw sectors of a formatted disk.

Also if you haven't got a bootable DOS disk, you might anyway want to build a simple interface between a modern computers serial port (or FTDI style USB TTL serial) and Atari SIO. I would build that interface with a switch that allows you to have it either emulate a SIO device (I.E. emulate a disk drive) using a modern computer, or act as a SIO controller (I.E. talk to a disk drive) using a modern computer.
This will both allow you to use your 800 even while your 1050 is broken, but also allow you to try to talk to the 1050 from a modern PC, I.E. you wouldn't need to type in commands over and over after each power cycle.
(this will of course not be of much use if the CPU in the 1050 doesn't even run code correctly, but still).
 
MiaM said:
Related tangent:
Note that it's possible to do some simple testing of an Atari 8-bit disk drive even without a bootable DOS disk.
I.E. it's possible to enter a short basic program that formats a disk and that reads/writes raw sectors of a formatted disk.

Also if you haven't got a bootable DOS disk, you might anyway want to build a simple interface between a modern computers serial port (or FTDI style USB TTL serial) and Atari SIO. I would build that interface with a switch that allows you to have it either emulate a SIO device (I.E. emulate a disk drive) using a modern computer, or act as a SIO controller (I.E. talk to a disk drive) using a modern computer.
This will both allow you to use your 800 even while your 1050 is broken, but also allow you to try to talk to the 1050 from a modern PC, I.E. you wouldn't need to type in commands over and over after each power cycle.
(this will of course not be of much use if the CPU in the 1050 doesn't even run code correctly, but still).
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Nice. I'm not worried about not being able to use the XL while the drive is broken- but that sounds like something I might build in the future. Sounds interesting to have a pc as a floppy emulator. These floppys tend to rot anyway.

I did get a box full of them with the drive.
 
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