Fairchild Channel F?

Just wanted to see if anyone had any advice or experience with the Fairchild channel F? The BEST i've been able to find is a few schematics and one video of the interior. I've been abel to test that power is making it to the motherboard but not getting a signal out. This is the first game system I ever had as a kid and for history it was the first game console to ever: use separate game cartridges vs. built into the unit and had a hold (pause) function. For historical and sentimental reasons i'd really love to get this running again.

 

No direct experience with this system, and you are right troubleshooting information is certainly sparse. However it doesn't mean we couldn't apply generic troubleshooting techniques. Any sound output? Have a scope to check for video signal? Low voltage on the +5V rail?

Programming/mod info:
http://channelf.se/veswiki/index.php?title=Main_Page

Schematics:
http://channelf.se/veswiki/index.php?title=File:FVE100_schematic_sheet_1of3.gif

While these links are not directly related, they have some troubleshooting info:
http://atariage.com/forums/topic/216141-need-help-with-a-fairchild-channel-f-issue/

http://atariage.com/forums/topic/154108-channel-f-composite-mod/

 

I'm getting nothing output wise. I just started to open this up little by little. I was hoping to find the transformer bad or a bad wire but no such luck. I just read where folks who find these old machines sometimes just booth them right up cold and it blows something on the circuit board. Apparently they should be left room temp for about 48hrs before firing up one of these that's been sitting for years. Appreciate the help! Even if I can't get it running, the games are worth more than I paid total for all, and it will look nice in the display till I get a working one.

 

I'm not 100% familiar if there is an rf switch. But bypassing that would be a good idea, if you have access to an older CRT testing it on that might be wise as well. Could be as simple as a bad RF cable, my Odyssey 2 had a similar issue with a break near the end.

Also it looks to have built-in games as well? Assuming the same result with and without cart.

 

Yes, i've tried with and without games. I'm looking for a CRT, currently i'm trying an RF to Coaxial adapter. The thing about the Fairchild is everything is hardwired. The controllers, the RF cable, the power supply. Once I open it up some more, perhaps one of the wires is loose. Once I get it working (hopefully) I can test the controllers and if you've never seen a Fairchild controller.....it's unlike anything ever...lol.

I really appreciate all the ideas and i'm going to check each one. Great group here!

 

That looks like the first generation Channel F with the discrete logic video section - so it should be giving you something on screen even if the CPU is dead. I would start by checking the power rails and if they are OK then check the clock oscillator (3.58MHz xtal) - they are a common failure item in old equipment.

 

There might be something apparent on the motherboard and you could see that it's damaged. Could be a blown fuse, a capacitor, damaged power circuitry or other things.

You need to get this thing alive ! It deserves to live !

 

I haven't heard of anyone else here that has one but..If anyone needs Cartridge labels for 1, 2 or 4, I found extras when cleaning out the box mine came in. Let me know and i'll just mail them for free if in the states. (if anyone has an extra label for cart 9, i'd greatly appreciate it btw).

 

I have one in working order, I will see if I can help with anything

 

Thanks so much, i'm modding a few XBox's for friends and family but when i'm done, I plan on getting back to the Fairchild. I'd really love to get it going but I'm just a novice at these type things.

 

looking on ebay there are a few new replacement mosfets, so maybe thats a common fault?

 

Thanks, I noticed a bunch of different part numbers on those mosfets. Not sure which are correct or are they all parts of the board? I wish there was a way I could make sure there's for sure nothing coming out of the rf cable. I've looked for some type of affordable detector like the tool I use to detect if there's power to different sections but no luck. I'm using the below picture to connect to a CRT since the original switch is missing. I have 3 XBox's im modding and loading up for family/freinds, then I plan on getting back to this conundrum. I really appreciate the suggestions fella's, i'm a total novice at this. Since this was my first (well second if you count mattel football) video game system, I really want to get this going.

 

Took a long break due to Modding A LOT of XBox's and a few PS1's for freinds. Been through the system now and unfortunaetly there's no "smoking gun" that was easily discovered.

One question: Does the small red bulb here light up if power has made it to that point of the board? Just using a basic AC detector now which shows power coming from the power box and to the board but its so damn sensitive it goes off when I get close to anything powered.

Any idea's of what to try? Ive checked a few places like Console5 for parts but they were all for the Fairchild Channel F II and I have the original.

I'm just a basic repair guy with no formal training looking for a litle guidance. Willing to shoot in the dark a few inexpensive idea's. I'd hate to give up and just go buy another tested one. really like to save this one if possible.

FYI: I did try another RF cable & something small is rattleing around in the wall plug.

 

An AC detector probably won't detect anything past VR1 and VR2 on the schematic, as everything after that is running on DC (VR1 and VR2 are rectifiers).

If you have a multimeter, try to see if the 5V rail is still at 5V or if it dropped. If you don't have a multimeter, get one, as it's really one of the main tools you need to troubleshoot and repair stuff.
The Extech EX330 is good and quite cheap (50$ on Amazon).
Please don't buy a 5$ multimeter. A decent multimeter will last you for the rest of your life and it's a really useful tool to have in your toolbox (Get it calibrated every few years and you're good to go).

Looking at the schematics, most of the parts are standard off-the-shelf components (or were at one point).
You'll have more chances of finding them at places like DigiKey and Farnell. For stuff that is not produced anymore, eBay will be your best bet (But check Digikey and Farnell first, to see if they're still available).

The circuit is not that complicated, it's really a matter of replacing the capacitors, checking the power rail(s), checking the few diodes there is.

On the schematic, the part you should be interested in is the very bottom, marked "Power supply". You didn't mention there were any sound, so my guess is that the problem is the power supply (I suppose you have tried to start the game blindly, of course), otherwise even with no video, there seems to be an embedded speaker inside the unit (The circuit coming out from pins 1 and 38 on the chip marked "PSU") and you should hear sound.
Using a multimeter, you can check DC voltage after L8 and L9. L8 should be +5V and L9 should be +12V. There is also a -5V you can check at C7, used for the RAM.

Replace the electrolytic capacitors, whether the power supply outputs the correct voltages or not (If it doesn't, it might fix the problem and if it does, you'll prevent another potential problem down the line. Replacing caps is the first thing to do on any old electronics).
I suggest Rubycon, Nippon Chemicon or Nichicon branded capacitors, these are the best and most reliable brands. Buy them on DigiKey or Farnell, as there are a LOT of fakes elsewhere.

If the rails don't output the proper voltage, check the diodes (D1 to D8 on the schematic) using a multimeter. If they're still okay, you can try replacing the 7805 and 78C12. Those are standard voltage regulators, still in production. You can get them on DigiKey and Farnell.

If the rails are good, you can check amperage on L8 and L9. Put your multimeter on amps. L8 should be around 1.5A and L9 should be around 250mA, if the schematic is correct. If they're in the correct range, the problem might be in the RF circuit. Otherwise, one of the chips might be fried.

Disclaimer: I have never worked on a Fairchild Channel F. I just looked at the schematic and tried to troubleshoot from there.

Disclaimer 2: Poking around in the power supply can be dangerous. Be very careful and don't put your fingers anywhere. Don't put your probe anywhere without knowing what it is/should be first.

 

Thanks so much, I already have a Etecity MSR-P600 Multimeter on the way but if that sucks i''ll go with your reccomendation. I little while back I found the schematics at Atari age so at least I have somehting to work with.

Thanks again, i'm a total noob at this type repair but as stated before. This was my first game system ever and holds a lot of sentimental value since My sister (who has since passed) and I used to play it for hours and hours. I really appreciate the help and the time taken to respond.

 

No problem

The first few times can be weird and difficult, but this circuit is not complicated and should be fixable There are very few better systems to start troubleshooting with, I think
The good thing is that almost everything seems to be made out of simple components or off-the-shelf parts, and the circuit is incredibly easy to understand.

The Etecity MSR-P600 should be okay in the short term If this is the only repair you'll do, it's more than enough. My recommendation is more if you plan on doing this semi-regularly (And if you intend to refurbish things often, you may even go for a Fluke, Keysight or similar professional brand, but those are really expensive and not worth it if you don't use the multimeter almost every day and for more advanced things)
The Extech I recommended is the one I use currently and I chose it because it has a very quick continuity tester, has good enough precision for what I do and was not too expensive (I found it through EEVBlog, a pretty cool electronics channel and forum)

The schematics I used are those linked by FuzzyFish above. They're very clear and easy to read (Provided you know how to read a schematic, of course. There are cheatsheets of the symbols online if you don't)
The PCB inside the console should have a silkscreen (the white text on PCBs) with the component's names. You'll most likely be able to find L8 and L9 near where the power cord is soldered. There should also be a transformer nearby (Big block) and most likely one or more big capacitors.

 

Again..thanks so much! I've been watching a few you tube video's and made some cheat sheets n how to read and apply electrical schematics. ..it's just translating whats on paper to what I see that's going to be fun..lol. No worries, it's a pretty basic board and really important to me. Hopefully I can have this up and running soon. I REALLY appreciate the help that's been given.

 

Tested the Transformer and it's outputting what it should on both red/yel and blu/wht. Started going through the board and so far no problems, got cut short with some family stuff..hope to get back on it soon..

 

Looks like someone's been in here before me. If i'm reading things correctly i'm missing two integrated circuits (in picture). Trying to track down a picture of someone good board right now for comparison. I found some semi-pictures that do indeed show there shuld be something in those spots but they are not very clear as to what.

 

I will take mine apart and see what you are missing