tjsnhgaming Posted August 18, 2021 Share Posted August 18, 2021 Hello, I recently picked up a 7800 to do a composite A/V mod on, and found the following burnt out component, and another that looks like it was never attached (with the red arrow pointing at it .. did Atari ship a unit that failed QA?!) : This obviously needs to be replaced, and that other component connected, but can anyone identify what that is? In some pics online it looks like its supposed to be a resistor, in others it looks like its supposed to be a diode (maybe?). Any insight would be greatly appreciated. The rest of the board looks like its in good shape, no loose or burnt out components. I've already got replacements for the 3 barrel caps and the voltage regulator ready to install (along with the A/V kit) but I'm hesitant to do any work before I can figure out WTF to do about this burnt out little part. Quote Link to comment Share on other sites More sharing options...
marauder666 Posted August 18, 2021 Share Posted August 18, 2021 (edited) Capacitors, probably 0.1uf, three different styles, but all the same thing. Worrying that one burnt up. Edited August 18, 2021 by marauder666 1 Quote Link to comment Share on other sites More sharing options...
+-^CrossBow^- Posted August 18, 2021 Share Posted August 18, 2021 That is a small bypass capacitor. Not sure how it got cooked like that as I've only seen that happen when you apply the wrong polarity of voltage to the system yet you still have the normal 7800 power port on the board? I can't recall the value right off hand. The other component that doesn't look like it is attached, appears to be where someone was trying to fix the issue by soldering in a replacement and attaching to the bottom leg of the other capacitor that burnt up instead of just replacing out the failed capacitor in the first place. BTW the two photos you attached are both capacitors. The one that looks like it is in a glass shell is actually an early SMD capacitor incased in a glass enclosure but still a capacitor all the same. 1 Quote Link to comment Share on other sites More sharing options...
+-^CrossBow^- Posted August 18, 2021 Share Posted August 18, 2021 5 minutes ago, marauder666 said: Capacitors, three different styles, but all the same thing. Worrying that one burnt up. My guess is that some one tried to power the system through this capacitor instead of attaching leads where they should have been off ground and the ferrite bead before the main filter cap. That is really the only way I can see how this happened. But the amount of voltage required is what is most troubling as I think most of these are or at least the ceramic ones like the green shown, would be about 50v rated? Quote Link to comment Share on other sites More sharing options...
tjsnhgaming Posted August 18, 2021 Author Share Posted August 18, 2021 Good info - thank you guys! The one thats lifted is labeled C56 under it (on the board) but I can't find that referenced on the diagram on console5 (I may just be blind). My best guess is, the one that isn't attached serves some function on the board that reduces the load or something on the pop'ed one. The system came with the original Atari wall wart and powers up (I only had it on for 5 seconds or so to verify the power LED came on, before I opened the shell). Quote Link to comment Share on other sites More sharing options...
marauder666 Posted August 18, 2021 Share Posted August 18, 2021 50V minimum! Quote Link to comment Share on other sites More sharing options...
+-^CrossBow^- Posted August 18, 2021 Share Posted August 18, 2021 42 minutes ago, tjsnhgaming said: Hello, I recently picked up a 7800 to do a composite A/V mod on, and found the following burnt out component, and another that looks like it was never attached (with the red arrow pointing at it .. did Atari ship a unit that failed QA?!) : This obviously needs to be replaced, and that other component connected, but can anyone identify what that is? In some pics online it looks like its supposed to be a resistor, in others it looks like its supposed to be a diode (maybe?). In looking at that second pic again, it looks like that second cap that isn't attached, might be bulged a bit as well and they were attempting to clip it out of circuit perhaps to measure the value from it. I believe it is the same cap that was where the other burnt one is located. Quote Link to comment Share on other sites More sharing options...
tjsnhgaming Posted August 18, 2021 Author Share Posted August 18, 2021 (edited) I removed the toasty component, and the board is charred underneath, so I wasnt able to get a part number. The disconnected part, which in all the pictures looks like its the same thing, is C56 but I can't find any confirmation what value that part is. The half-attached cap in C56 also doesn't have any markings on it, I even got in with the eye loop, so no luck there. Google is failing me hard today trying to find 7800 parts lists. ? Edited August 18, 2021 by tjsnhgaming Quote Link to comment Share on other sites More sharing options...
+-^CrossBow^- Posted August 18, 2021 Share Posted August 18, 2021 You have you answer as I answered you on FB...but these are MLCC caps located at C57 and C56. (Although C56 is mislabled in the newer schemes as C58). Both are 100nf (.1µf) 50v caps. Console5 has them on hand as they are used in lots of applications and the 7800 main board haw quite a lot of them throughout it. 1 Quote Link to comment Share on other sites More sharing options...
tjsnhgaming Posted August 18, 2021 Author Share Posted August 18, 2021 5 minutes ago, -^CrossBow^- said: You have you answer as I answered you on FB...but these are MLCC caps located at C57 and C56. (Although C56 is mislabled in the newer schemes as C58). Both are 100nf (.1µf) 50v caps. Console5 has them on hand as they are used in lots of applications and the 7800 main board haw quite a lot of them throughout it. Thank you, was JUST about to post an update here with this info incase anyone else stumbled along with the same issue. These are the ones I ordered as a replacement: https://console5.com/store/1uf-10-50v-multilayer-ceramic-capacitor-mlcc-axial-leads.html After the AV mod is done I'll post back about that so people can mock my sloppy modwork ? Quote Link to comment Share on other sites More sharing options...
+-^CrossBow^- Posted August 18, 2021 Share Posted August 18, 2021 BTW... I would think about replacing out that cap at C56 as well. It should have markings on it and it looks...off to me like it is bulged a bit abnormally. Quote Link to comment Share on other sites More sharing options...
Like us on Facebook
Follow us on Twitter
AtariAge on Instagram
Watch us on YouTube
Chat on Discord
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.