De-Soldering - Soldering disaster STE

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Winner61
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De-Soldering - Soldering disaster STE

Postby Winner61 » Thu May 10, 2018 9:37 am

Hello all. Let me introduce myself first as this is my first posting. I am a Dutch Atarian from almost the beginning, my first was an 600XL around 1980 and played with it for a while. For I did not have a recorder for it all my staking basic-programming work was gone after I switched off. I traded it in for an MSX wich was also nice to have (still have that one too). 86 was the year I got my 1040ST which was a huge step-up. Used It for music & graphics, animations and offcourse some gaming:-). Still have that one and just did an rom upgrade from 1.02 to 1.04. After a little hickup all went well. Begin nineties I purchased a TT, in that time I made lots off adds for my business then. Still have the old TT with nice extra's like a graphic card and nice memory upgrade. Used Calamus & Outline art quite a lot. The ST degraded a little to the fun side of things like Chuckie Egg and Leisure Suit Larry amongst others.
Just a few weeks back I purchased an STE with a French 1.62 ROM and 4MB memory. Purchased a 2.06 ROM and opened the casing. Great disappointment to see the ROM's were soldered on the board. I am quite a handy man and have done a lot of fiddly work over the years. Did not really do much of mainboard soldering like this but I'm not one of the fainthearted (spelled good?) so I dug into it. Watched a lot of YouTube soldering video's and got also info from the Atari-Forum. But now for the real story: I made a big mess of it and damaged quite a lot as you can see in the pictures below.
I de-soldered the ROMS and put in DIP sockets. Propably here it allready went wrong, I still did not have my delodering iron with sucker so I used braid after I cut all the pins. I thought I did it quite clean. Put in the ROMS and started it up. Got a white screen... went over the solderings one more time and tried again. It looked hopefull for I just saw the atari logo for a few seconds and after that the screen went a little crazy. Restarted it a few times and then everything went black. After I got my de-soldering iron I carefully removed the sockets. The pictures below show where I am now. Started it up in hope I would at least have a white screen but NO, nothing, just BLACK. I must have fried another chip. Before I do an attempt to repair the damage I have to know what else can be broken. I really hope some of you have ideas and can help me with this project. I know, I should have trained myself in desoldering first on some old pc mainboards. I'm here now and it would be such a shame it would end here. Sorry for the long story and hope it was not to boring.
Would be fantastic if somebody can give me some insights. For example how to attack the repair on the mainboard. Is there a raisin to cover the scratches I made, can you get new bushes. But also, what can be the issue I not even have a white screen with averything clean as it is.
Thank you all.

Winfryd. :shrug:

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https://1drv.ms/u/s!Avq5N3rIv5eKyjYstxHSInmjb3HL
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Re: De-Soldering - Soldering disaster STE

Postby 1024MAK » Thu May 10, 2018 11:07 am

Hi Winfryd

You've got some lifted and damaged tracks and pads.

I can see some in the photo of the underside of the board:
IMG_7028.JPG


The damage I can see is indicated by the red coloured arrows.

With any luck, you have not destroyed the plated through hole connections. So what I suggest is the following:
Download and print out a schematic (circuit) wiring diagram of your machine. All the following tests are to be done with the machine disconnected from the mains power and from any other devices.
Using a multimeter on the continuity range, (or on the 200 ohm range if yours does not have a continuity range), test between each of the ROM chip pads (pins) and other chips that you have not worked on (for example, the CPU). Do this for the ROM chip pads (pins) on both sides of the board, and for both ROM chips. If the test is okay (meter bleeps or shows less than 5 ohms) Mark the relevant circuit on the printed out schematic with say, a tick in green or blue pen. If you don't get good continuity, mark it with a red cross. If the schematic shows the circuit going to many other chips or components, it's worthwhile testing at least as many other points as you can. As the tracks on a circuit board do not follow the layout of the schematic.

Where the track / pad is good on the top, but damaged on the underside of the board, use some very fine tinned copper wire (like very thin fuse wire, or wire strands out of a flexabe cord (cable). Carefully wrap it around the relevant pin of a new DIL socket (one and a half to two two turns) and apply just a little bit of solder. Leave plenty of spare wire, cut and do the next pin. Repeat as required. Then thread each of the wires through the relevant PCB holes followed by inserting the socket. Note plan ahead and do the sockets in a suitable order, so that you can still get to the relevant top (component) side pins of the sockets with your soldering iron.

Now solder the top side pads on the socket where you have your fine wires. Then solder all the underside holes where the pads are good. When the pad is lifted, if possible, see if solder will still take to the plated through hole. If the track to the pad is broken or the pad has lifted leaving no conductor to a track, if the gap is small, you can carefully scrape off the solder resist (green in colour on this board)m tin the exposed copper track. Tin the wire once cut to the correct length. Then quickly and carefully solder the wire to the track. Use a flat bladed screwdriver to hold the wire (unless you like pain).

Good luck ;-)

Mark
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Winner61
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Re: De-Soldering - Soldering disaster STE

Postby Winner61 » Fri May 11, 2018 9:16 am

Thanks Mark for tips on the repair. Some things like a very fine wire through the hole was also something I was thinking of. I examined the damage closely with a magnifier and think it's doable. Measurements with the multimeter show good results. Top of the board all seems well.
Before I take this task upon me I first like to have a white screen with no roms installed. I tested taking out the roms of my ST and without them I get this white screen so at least there is output to the screen. What may have broken in my STE, which chip is most responsable for video output or can the cpu be damaged. Last one is quite a cheap fix. Maybe I can even spruce the STE up to 16Mhz with the appropriate version. I hope to hear some similar experiences on reasons for black screens after hardware changes like the roms.
Thanks!

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Re: De-Soldering - Soldering disaster STE

Postby Winner61 » Wed May 30, 2018 8:17 pm

Succes in repairing. Fully working STe again. :D
I was a bit sceptical at first, afraid I damaged more things then the ROM area only. It was as if I was a baby-surgeon. Working with just 2 strands of wire to repair the circuitry. After careful soldering I took a long time measuring with the multimeter. No shorts and all the critical leads were tested and doubletested.
First 'contact' resulted in a big nothing, but that was without ROMS, memory and FD. OK, that was not very hopeful. So I put in the ROMS, memory and connected the FD and keyboard. AGAIN NOTHING, just black... only the bottom left green keyboardlight. Hope sank in my shoes (slippers by the way, it's hot). :idea: Then I remembered I did not put back the jumpers W102-3-4. Oké One more chance.... VOILA, the screen booted with the Atari logo and the FD made the proper noises. So great succes.
Next project will be a quatrro ROM for the STe, bought myself an eprommer and see how far I come. At least I have proper ROM sockets now. But first I'm going to play with it for a while.
Cheers!

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Re: De-Soldering - Soldering disaster STE

Postby wietze » Wed May 30, 2018 9:19 pm

Good to see both another STE saved from disaster and another Dutch atari guy \o/

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Re: De-Soldering - Soldering disaster STE

Postby dhedberg » Wed May 30, 2018 11:09 pm

Glad you got it spinning again! :-)
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Re: De-Soldering - Soldering disaster STE

Postby LaceySnr » Thu May 31, 2018 5:27 am

Congrats on bringing back to life! Such a nasty feeling when you think you've broken something like that.

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Re: De-Soldering - Soldering disaster STE

Postby Winner61 » Tue Jul 10, 2018 10:01 am

Followup on my STe. Installing a Quad ROM with this www.tehkella.net/retro/?p=257 guide. Bought myself a cheap eeprom programmer TL866A and eeproms from AliExpress which worked like a treat. Result in one GO. The only thing was that the wiring in the guide was a bit cryptic but looking closely at the images I got the meaning. In my picture you can sure make it out. Easy job if you are a bit handy.
Happy atari computing!
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Re: De-Soldering - Soldering disaster STE

Postby joska » Wed Jul 11, 2018 2:00 pm

Nice :) With a TL866A you're now only one GAL away from adding writeable TOS and an IDE interface to your STE.
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