cleoo

Thanks Robson for the suggestions. I replaced the main capacitor with a 2200uF and did change the C41 capacitor with a 100uF at the suggestion of Luke at Console5. But then I started to get distorted screens and got this 20 bomb screen once it settled down. I replaced the main cap back to a NEW 470uF cap I had for the Lynx and removed the C41 cap back to the original one. The screen was again distorted. Then I started to seat the large chips to see if they made a difference and I noticed the bottom chip (blitter?) was changing the screen display when I applied pressure at certain points. But then it finally cleared up and showed these screens. I reinstalled the 2200uF cap and also removed and reseated those two chips and now it boots onto the GEM desktop! So, the only issue I have is obviously the floppy drive needs to be fixed. It beeps and spins but nothing shows up on the desktop. I had to unplug it so it could get onto the GEM desktop. Each of the keys makes and audible sound on each press that I can hear through the monitor. The other issue I’ve experienced is the left mouse click doesn’t always work. I can now look into other options and getting it to work fully. Thank you.

Robson, how would I even disable the top row of “new” ram? I don’t have a schematic to figure that out right now.

Thank you. It had powered up to the green desktop after making most of the recap but something caused it to go back to the black screen. I’ll try those suggestions of yours as well. I’m nominally proficient at soldering so I was having difficulty removing the rock hard solder, even after applying fresh solder to the small vias. I soldered the large cap this way. The C124 cap looks jerry-rigged in the picture Console5 Luke sent. Can someone take a picture of their unmodified C124 cap for proper placement? It looks like the negative of the axial cap is on the small via near the and the positive is connected near the C124 via. Is that the positive?

Thank you both for the suggestions. I will give those a try. I was emailing Luke at Console5 and he believes this board was one of the early Rev D boards in the transition from Rev C because of the 470uF cap. He sent me a pic of how that 2200uF was installed.

So I turned it without putting the remaining two capacitors and got to this... Then when I went to attach the mouse. It went back to the black screen with white border.

I acquired this 520STFM a while back and started getting parts to get it to work since it would just show a black screen with white border. The PO said he upgraded the board to 1 MB as you can see the row above the original ram has been populated. So, I thought it was the PSU since it was old and those were problematic. I followed Jan Beta’s video and installed a Meanwell RD60 PSU. When I booted it, the only change I noticed and it was very brief, it was a very distorted white and green display-glimpse of a desktop? Anyway, i quickly flicked it on and off and it went back to the black screen, white border. So, I went ahead and started to replace the caps. Console5s caps were a little different than what was on the board On my board C35 is occupied with a radial capacitor 470 uF 16v. Console5 supplied an axial capacitor 2200 uF 16v. Is that still acceptable? Not sure if it will even fit. I also can’t find C124 on the board to put this 100uF 16v axial capacitor. Highest one on the PCB is C119. If you can direct me to it because I can’t find it. Also, looking through this board I see these resistors. Doesn’t look right. These look burnt and there’s a clear coating over part of the board. Any ideas with what’s going on with these mods? Thank you.

Hi I also got bearings from console5. Even though I ordered the bearing press. I ended up using this vise and a ball peen hammer to get it out and put the new bearing in. Does anyone have a technique to remove the plastic optocoupler without breaking it? So I can replace that bearing???

Here’s the motherboard. Can you see what the problem is?

I will have to look closely and see if there are any broken solder joints. I’ll report when I get a chance. Hopefully, Mike and I can each get answers to fix our 520STfm. Thank you for all the help.

I press on the reset and the monitor goes entirely white and then comes back with the black box.

Interesting that you said that. The previous owner said that he did a memory upgrade. (Did I just buy this from you? lol)

The keys don’t click. Nor do I hear any sound through the monitor. (Does it have speakers?) 1st time ST owner.

No activity from the FD. Light does not come on.

Hi. I just picked up a 520STfm also and it’s hooked up to a SC1224 monitor. Turned on the monitor first. Then turned on the 520STfm. I get this: I haven’t done any of the steps the OP did.

PM

What’s your best price?

You’re right about the bigger picture. I just focused on the smoking area and where it started to melt. Despite the shorting and smoking, the 5200 is pretty robust and still works!

My mistake. I forgot to remove this guy. I immediately realized it once I connected the RF cable to the switchbox. Sparks! Power mod works great now. Thank you.

The pair of caps for the sound are still packaged together. I didn’t install those.

Hi. I installed this power mod from Console5 with the quick disconnect and when I powered it up. It started to smoke near the capacitor at the base. The solder also started to bubble. Any idea why?

I happened on this thread to determine which FB2 was real or fake on some ebay listings. These pictures are from some sellers who were good enough to take a picture of the bottom label. Real Fake -Spacing is off. Sometimes there isn’t. Sometimes it’s too much. -Kerning is off -Fat Fuji symbol. Especially the middle leg. -ATARI is bolder with the leg of the R extending past the top of the R -TM is larger and sits below the top of ATARI -China is spaced out

+1 (Pokey, YM, Cable) in RED Thank you.

Prior to removing the mod, I tested the voltage leading to it on the board and it was putting out 4.94 volts (Same as at the Voltage Regulator, bottom pin). It seemed to be getting power. I'm going to try the mod on a woody 4 switcher and see if that one works. I read somewhere in this forum that Vader's have problems with video mods. I wasn't able to find what the reason was...yet. If the mod doesn't work in the regular way then I'll try that option.

Goes to show how much I know. ?‍♂️ The last post (#7) was showing how the CAPACITOR was before I put in the Console 5 white capacitor.

Here’s the original diode at C242