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Dropcheck

XF551 Mixed-Original Parts Bare PCBs

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FYI:

 

I have now finally gotten a 8.3333MHz XF551 OSC clone working rather consistently. What this means is that one of the hardest parts to locate is now finally relatively easy to get. This is a SMT parts board, so those who barely can solder TH would be advised to order a completely assembled board rather than a bare pcb, but it is your choice.

 

Essentially it is three parts assembled onto a plug in board to the main XF551 board. You would simply solder it into the original OSC footprint on the main board.

 

 

DSC_2982.jpg

 

DSC_2983.jpg

 

The bare board is running around $2.00 per and assembled will be around $7.00 plus shipping. tf_hh should be able to offer the bare boards as well to those in europe. I don't know if he wants to assemble them.

 

I currently have 8 bare pcbs available, with the usual option to order more if there is demand. Website should be updated in 24hrs or less.

This the kind of thing I enjoy seeing, nice job!

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The bare board is running around $2.00 per and assembled will be around $7.00 plus shipping. tf_hh should be able to offer the bare boards as well to those in europe. I don't know if he wants to assemble them.

 

Sure I will :)

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Looks like a slight part # change is coming. tf_hh has advised me that some copy protected disks may not load/run at 33MHZ divided by four. He's advised me a slightly higher OSC speed is necessary. After looking at the part pcb footprint, I don't see any change needed on the board. It will fit and be solderable. So I will make a change in the BOM listing and replace the part on assembled boards.

 

If you have downloaded the AltOSC BOM file from my website, discard it. The new one should be up in a few minutes.

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FYI:

 

tf_hh will be offering an assembled version of the alt OSC board starting next year. So those on that side of the pond can put the big bills for shipping away. ;-)

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Some of the things I have read about a 3.5 drive have led me to believe that the 3.5 can't be used as drive 1, is this a fact or just my misinterpretation.

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Some of the things I have read about a 3.5 drive have led me to believe that the 3.5 can't be used as drive 1, is this a fact or just my misinterpretation.

I have a CSS dual drive upgraded XF551, the 3.5" mechanism responds as ID+1. BITD I was able to format and install SpartaDOS to it as D2:, then boot from it after re-assigning D2: as the boot drive in the config of my MIO.

 

Bob Wooley has also been able to boot from an XF551 converted to a 3.5" mechanism.

http://atariage.com/forums/topic/108472-xf551-oses/page-2?do=findComment&comment=2061120

Edited by BillC

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Some of the things I have read about a 3.5 drive have led me to believe that the 3.5 can't be used as drive 1, is this a fact or just my misinterpretation.

It would be the result of the misapplication of a few facts.

 

1) XF-551 drives must be drive zero in zero based

counting systems or drive 1 in standard decimal count.

 

2) Modern 3.5 don't have drive select jumpers anymore

and they are set to be 2nd drive by default.

 

3) you can't get there from here as long as you

obey 1 and 2 above. And you just don't have to play

that game.

 

Although the jumper pins are gone, the pad that used to

sport them is still there and solder blob selects 2nd drive

in the PC way of twisted cable use. Move the solder and issue

is resolved.

 

I can only add - some issue.

 

How lame is it to let people walk away thinking you can't

do this when you certainly can quite easily.

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I have a Sony drive on my XF551 that I had to jumper DS0 and remove the jumper for DS1 on the PCB (jumper=solder blob). It boots fine with DS/DD formatted disks (for example MyPicoDos with a bunch of binary games). As far as copying a 90k SD disk to a 3.5" disk, no can do on my drive.

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I have a Sony drive on my XF551 that I had to jumper DS0 and remove the jumper for DS1 on the PCB (jumper=solder blob). It boots fine with DS/DD formatted disks (for example MyPicoDos with a bunch of binary games). As far as copying a 90k SD disk to a 3.5" disk, no can do on my drive.

Instead of changing the DS jumper on the mechanism I would recommend changing it on the XF551 PCB. Atari implemented DS0 by connecting it to the MOTOR signal, doing the same with DS1 would accomplish this and allow use of mechanisms without select jumpers.

 

There would be no issue with having both selects active with only 1 mechanism connected,

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Some of the things I have read about a 3.5 drive have led me to believe that the 3.5 can't be used as drive 1, is this a fact or just my misinterpretation.

I have an xf that I converted to 3.5 bitd and it most certainly boots as D1: without and tricks, and can be assigned as 2 3 or 4 as well, just like any other xf

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I have received notice that Atari apparently decided to use two different power plug footprints in various models of XF551 boards. :(

 

They are almost exactly opposite of each other. One will fit my board, one will not. If you haven't yet purchased my board, but are planning to check your original XF551 power plug footprint. It should match the picture in the first post of this thread. If you have already purchased my board, check your original XF551 power plug footprint against my board. If they are the same great, if not then there is a fix. It ain't pretty, but it will work. An AtariAge member who purchased my board recently made this unfortunate discovery and came up with a fix. I am passing along his info below.

 

Atari%20power%20plug.jpg

 

" I am attaching a picture of the modification I made to the power connector. You have to bend out the piece that would go through the solder hole, rotate the metal 180 degrees and then solder a piece of metal vertically to go through the hole."

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I have received notice that Atari apparently decided to use two different power plug footprints in various models of XF551 boards. :(

 

They are almost exactly opposite of each other. One will fit my board, one will not. If you haven't yet purchased my board, but are planning to check your original XF551 power plug footprint. It should match the picture in the first post of this thread. If you have already purchased my board, check your original XF551 power plug footprint against my board. If they are the same great, if not then there is a fix. It ain't pretty, but it will work. An AtariAge member who purchased my board recently made this unfortunate discovery and came up with a fix. I am passing along his info below.

 

Atari%20power%20plug.jpg

 

" I am attaching a picture of the modification I made to the power connector. You have to bend out the piece that would go through the solder hole, rotate the metal 180 degrees and then solder a piece of metal vertically to go through the hole."

 

 

I've found the problem. Apparently Atari decided to use up their stock of 1050 power jacks in the initial run of XF551. When they ran out they switched to a slightly different footprint for the power jack. It looks very similar , but with that one critical difference. I am working on modifying any new boards produced so that they can handle both versions of power plugs.

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An easy fix for those whose salvaged power plug part is the 1050 version and you have the current version of XF551 Mixed Parts board is this Part# PJ-102AH.

 

I am linking to Digikey.com, but there are other suppliers.

 

Sorry for the delay in posting, but I'm neck deep in working on the SF314 version of this board.

 

Also from the same AtariAge member who is assembling this board and using the previous power plug modification, he is reporting this:

 

"Inform your customers that they need to attach both voltage regulators, and the bridge rectifier to the heat sink, then attach the heat sink to the PCB, THEN solder in the regulators and rectifier. Otherwise there will likely be alignment problems and it is really difficult to get the screw into the hole for the rectifier because the power jack is in the way."

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I found some AC common mode chokes from MOUSER that have exactly the same footprint size and they look almost exactly like the one on the PCB. I don't have any electronic knowledge so I can't judge. Are there any resistance or voltage specifications associated with the choke that I could use to determine compatibility.

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I found some AC common mode chokes from MOUSER that have exactly the same footprint size and they look almost exactly like the one on the PCB. I don't have any electronic knowledge so I can't judge. Are there any resistance or voltage specifications associated with the choke that I could use to determine compatibility.

 

Yes and you can't go on just looks alone, you have to have the same dimensions as well and the same 'internal' wiring. Mouser used to carry an AC Line Filter that I used in my earlier XF551 boards with the original power supply circuit, but the manufacture stopped making them and Mouser eventually ran out of their inventory. It does fit the mixed parts board version as well.

 

This is the Murata Part #PLA10AN1522R0R2B I was using

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Mouser has some that have the same exact dimensions but different resistance etc are there any published parameters that would help find an acceptable replacement. I would like to be able to build a board with no recycled parts.

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The Mixed Part board was designed to reuse some parts from the original board. Because some of those parts are no longer being made, you will have to recycle from an original board. Newer parts most likely will not have the same board footprint or specifications. I made that plain in the very first post of this thread.

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I have been able to find all of the parts except the AC choke and the heat sink. The heat sink would be easy to fabricate. The reason for my reluctance to recycle parts is that I have a 551 with a bad pcb. I don't know if it is a problem with the board itself or one or more of the components and it is almost impossible to troubleshoot the PCB.

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The most common XF problem is broken or fracture trace at power jack and sio port, sometime near hot components like voltage regulator. The other is sometimes the track sensor.

 

The fix is usually easy...

 

It really should not be all that difficult to find a suitable choke or have something made... same as fabricating a suit able heat sink..It's just a heck of a lot of work for some folks who do not have the time, tools, or money.

Edited by _The Doctor__

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I have been able to find all of the parts except the AC choke and the heat sink. The heat sink would be easy to fabricate. The reason for my reluctance to recycle parts is that I have a 551 with a bad pcb. I don't know if it is a problem with the board itself or one or more of the components and it is almost impossible to troubleshoot the PCB.

 

If you have a bad XF551 pcb then you have the AC choke and the heat sink. The AC choke doesn't normal go bad.

Edited by Dropcheck

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I appreciate what you have done with the board development. I don't understand why you want to shoot down my effort to populate it with all new parts. If I could do that I could convert a 3.5 into an Atari 3.5 without the need of an existing XF551.

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I appreciate what you have done with the board development. I don't understand why you want to shoot down my effort to populate it with all new parts. If I could do that I could convert a 3.5 into an Atari 3.5 without the need of an existing XF551.

 

Some of the parts used in the board have been obsolete for years and 'new' parts are hard to find if at all. That's why I stressed salvaging from an existing XF551.

 

I gave you the link to information on the AC Choke that I used in earlier designs and that would fit this Mixed Parts board in post #91. You can try an Ebay or Google search for the part #. I haven't found a source yet. Maybe you'll have better luck. Perhaps someone here will give/sell you their extra one.

 

If you do not have an original XF551 to salvage the heat sink from then you will have to supply a substitute somehow. Probably individual heat sinks for the bridge rectifier and the two voltage regulators. You might have spacing issues though. I have no idea of a specific part # that will fit. You can try Best Electronics to see if Bradley might have an XF551 heat sink.

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