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XF551 Power Issue


MacRorie
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Hello folks,

 

I have a question for y'all:

 

I acquired an XF551 that--for various and sundry reasons--does not power on. The power switch was jammed up and I got that to actually operate (I think) now, but when I try to turn it on, I only get a *brief* power flash and then nothing. This power flash happens when I turn it OFF. Any suggestions? How to troubleshoot, etc?

 

Should I replace the switch? If so, any suggestions? What is the switch type called? I am headed to Fry's today for other reasons, but if I knew what the switch was called, I could buy a replacement and see if soldering a new one helps. OR, is there any way I could temp rig it to "always on" and see if it is the switch or something else more dire?

 

Thanks

-Mac

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AtariGeezer makes a very good point, if this is your first XF-551 you may not know it was on all this time as they do just flash red LED and then sit there. So the word briefly needs finer tuning applied, briefer than a good working XF-551 or is it under a tenth of a second flash? Half second flash for normal XF-551 but that's just a guess.

 

You'll have to replace the switch if you can't free it up. But they can be disassembled and forced to free up, I would do this before anything else. Pry the rocker off of it at it's side clips to push down on the stubby actuator to shoot WD-40 inside. Then work the devil out it with pliers on that stub until free smooth action is what you get. If you can't get here, you'll need a new switch.

 

Double Pole, Double Throw (DPDT) is the function type, but that company made dozens each with several different options so your chance of finding one with the same look and feel of the original is about the same as playing LOTTO. Yours also has PCB, thru hole, 90 degree mounting. Rocker with no center position. Best electronics will have the exact switch for replacement, but no one else. Any DPDT switch could be made to work if it's of a similar size, guys across the pond replaced theirs with a long toggle handled one that really is better than fishing around back there blindly trying to feel for `the rocker in my opinion.

 

Jammed switch in the first place is the only indication you needed to point fingers at what's wrong with power, fix it or replace it. I've had pretty good luck with shooting WD-40 past the stubby actuator ball joint/seal, but you have to push it down to get the clearance past it to allow that to happen. They can be so jammed that the ball won't budge.

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It's not my first XF, but it has bee a few years.

 

Let's put it this way:

 

I got the switch loose, so I can turn it off and on, I presume (this assumes that the switch still functions).

I try to boot from it, and get no reaction, it just errors out. I try to read a disk from it, not luck. Theses a known good disk. I do not even get a flicker on the access light when I try to do any of this.

 

The motherboard of the unit DOES have what looks like patching on the SIO ports. IIRC those were notorious for failing and it looks like the prior owner may have wired them up.

 

There could have been a crack in the motherboard during shipping (the cause of the stuck switch as well I am thinking).

 

If there is anyway I could test the SIO ports, that might help me rule out some problems (because if the SIO ports have failed, this would explain the lack of access lights on trying to boot it/access it).

 

Thanks for the help and I am open to anything.

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Check the address switches - are they right? If you can't boot off the drive as D1:, boot MyDOS on another D1: drive and see if your XF551 will respond to any other address (D2:- D4:).

 

If you still get no response, try each of the two SIO ports individually. Often, one of the ports works and the other does not.

 

Try a device behind the XF551 in the SIO chain. If the PCB is mangled in the SIO wiring, the SIO signals will not be propagated to the next device.

 

Bob

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On SIO ports, pin 1 to pin 1 should always show continuity, 2 to 2, 3 to 3, ect. Measure for voltage elsewhere, and if you have some, then power is getting thru the switch. Since SIO has been repaired, you should consider it was done incorrectly and verify everything at this point. Cracks in motherboard were never the problem with these, it was shoddy rivets that allowed the SIO jacks to move and break loose the solder connections, to lesser degrees the same happens to the power jack and power switch because they move first and then break loose solder connections, JB weld epoxy for those two, pop rivets or machine bolts and nuts for SIO jack. You must first fix the movement part of the problem. Then sanely you can re-solder, soldering before fixing the movement problem is not sane behavior.

 

Switches stick when they are not used for decades at a time.

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Thanks for the help. I tried everything and the SIO pass through worked fine, but still not recognition. So, I got a wild hair and put the switch in the middle (sort of between off and on). Lo and behold! It works! So, I will have to replace the switch, but at least it works now!

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Use contact cleaner in that switch, and protect/keep it from getting on other stuff, then do the same using wd40.....

the switches sound like they corroded and bonded from non use.... electrical contact cleaner and wd40 with lots of switch flipping almost always clears it up for me. Off chance it doesn't I open the switch up on Atari stuff and rebuild them... nothing looks quite correct other than the originals for some reason...

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  • 3 weeks later...

Hello, all, instead of starting a new thread, I thought I would hijack one of my own on the XF551. How do you tell the difference between an "original" power/control board and a "modern" one?

 

Thanks

 

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I said a stock board, that means original.

Understood. However, I was under the impression that there were two different boards that shipped with the XF551. If that is the case, then both could have been "stock," correct? So, I guess my question now is, if that is a picture of the original board, how is it different from the stock "modern" board?

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So, I guess my question now is, if that is a picture of the original board, how is it different from the stock "modern" board?

On the underside there were two versions of power input solder pads and routing of same, IIRC. It's not a major change visible in a shot of the top side. Both versions were stock, calling them modern just confuses the issue with Dropcheck's recent release. I would say most don't know that there are two versions of power jack circuits in the first place, so how can such a distinction be widely addressed? They both worked until the jack started moving around and then they both failed on occasion. One can't be called better than the other and I have no idea which came first or even if it's possible to discern such from a possibly missing bottom tag since I don't know the serial number break point there. Early and late might be a better way to word the question, but I still have no answer to which was which.

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The only XF551 mainboard which could be described as "modern" (these drives being twenty-five years old) are DropCheck's reimaged XF boards, distinguishable not least by the fact they're double-sided PCBs.

 

 

I get that, but DropCheck uses that language in the ordering process and in the install process. So, I am trying to figure out which one to order. I ordered the replacement for the "modern" version, but I am only guessing. I was trying to verify which one was correct.

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