TheSolderMonger

I'd like to be put on the list too if there is still room. Many thanks

Could you check the 1000 uf capacitor and see if it's outputting 23 volts? It could be that the cap is bad. Also, I checked 2 caps on the logic board close to the regulators and they are getting 12 and 5 volts, but I check the other end and my probe gets nothing. Could that be a sign of a faulty capacitor?

On my machine, the eject button pops off (like a lego brick) , not held in by screws/glue and the RF shielding pops off easily, just leaf spring metal pressure. I still recommend caution on your machine since mine was slightly disassembled when I bought it.

Drat, well that rules out the PSU. I'm looking at doing a recap of the main logic board or a MUCH closer look at the soldering to rule out cold/broken joints and another 12 regulator replacement. Could it be possible for you to measure the 12 volt regulator INPUT voltage? If so I could reverse the path of the traces to a possible malfunctioning component.

Were you able to get the voltages?

I did measure 10 volts from all 3 pins from the PSU brick to the daughter board. Can you measure your PSU output voltage from the brick?

When I setup my channel F on my CRT instead of the flatscreen, I saw that the signal persists, but this is what the problem causes the picture to do. Could this have something to do with the RF circuitry? Or would this have to do with power and/or thermals?

Yet another update, there was some residual electrolytic fluid on the daughter board, and there was a capacitor on the main logic board that had 1 leg unsoldered, and with that the problem still persists, though I may disassemble the switches themselves as a couple of them don't make clicking noises, perhaps stuck buttons cause glitching with conflicting instructions?

Update: Applying thermal compound and a small heatsink did nothing to improve the picture. I still smell electrolytic fluid coming from the daughter board, even after cleaning a good portion of the leakage. Now I need to soak the daughter board in alcohol and see if it changes color, if it does, then there was electrolytic fluid possible conducting power where it should not be going.

I measured the Input/output voltages and with that, the UA7812C regulator is regulating 23.3 volts down to 12.19 while the UA7805C is regulating 11.63 volts down to 5.03 volts. What I may do is to use a small heatsink over the regulator, and if the heat dissipation keeps the system on and working then the problem lies in the regulator or at least narrows down the power path to the regulator.

Sure thing, attached below is the daughter board and the regulator arrangement. The regulator on the left is a UA7812 and the one on the right is a UA7805.

Update: The issue at hand seems to be caused by a thermal problem, however the 1976 service manual screenshot 104 seems to match with my earlier uploaded picture of the white line, which points to a faulty PSU. I'm inclined to believe that the PSU is normal, and that the regulators may be in the wrong spot, as the UA7812 regulator is hot to the touch after the TV loses signal. Prior to the signal cutoff, with the regulator cold, the system works just fine until the regulator heats up, and likely causes a drop in the 12 Volt line? (Again, I'm not sure if the regulators are even in the right spot.) I would greatly appreciate if masschamber could upload a pic of the regulator setup, because if the person who last serviced the machine put the capacitors backward, then I am likely to assume the regulators were also put in incorrectly.

Replaced the voltage regulators and the problem still persists. Can you provide a picture of the regulators at the back to make sure that these regs weren't put in the wrong way.

Can you upload a picture of where the regulators are? I replaced that capacitor later after the picture was taken, it was no good.

I thank you so much, however this problem (see attachment) still seems to persist after re-aligning the capacitors and powering the system on for a few seconds with or without a cart installed. When I power the system on the game shows up with a bit of garbage but then the picture goes to this line and then the TV loses signal.

Update: I fixed some broken solder joints on the switchboard area, but the capacitor blew AGAIN! Funnily enough, the sound works, I hear the pong sounds coming from the system, but when the cap blows it goes away? So either the capacitor is in the wrong orientation or my Channel F's PSU brick is shot. I really need you fellow channel F owners' help. I don't know what the voltages are for the Red White and other Red lines, though when I measured them Earlier they all measured about 10 volts.

Here is my picture of the new caps soldered in. The Radial Cap is the 1000 uf cap that replaced the blown 1000 uf Axial cap.

Update: Soldering a new 1000 uf and 2200 uf capacitor doesn't seem to be solving the problem. The 1000 uf cap in particular heats up extremely fast and I have to constantly shut the system off before the cap blows. With that, I have a new theory: The original owner had replaced the cap in the wrong orientation, causing it to blow and then giving up before selling it. With that, I ask that someone with the Channel F System 2 attach a picture of the switchbank area, where the 2 capacitors are, with the directional bands on the caps visible. I myself will attach a picture of my board and see if it matches with other machines.

I have reason to believe that the larger 2200 uf capacitor is bad, I measured both it and the blown cap, with the 2200 uf measuring at 9V while the 1000 uf (blown) is measuring 19V. Perhaps a bad 2200 uf cap caused the smaller one to overcharge and therefore blow. I'll have to wait until the replacement 1000 uf caps come in before I try again.

Hello again AtariAge! I've got another project needing your assistance! I recently acquired a Fairchild Channel F from a game fest in Austin and when I tested it, the game came up with some glitching but quickly vanished, with the TV losing signal. I saw a capacitor was leaking and replaced it with with a capacitor of the same capacitance, voltage and direction, and when I powered on the system, the TV made buzzing noises and the 25V 1000uf Capacitor I replaced is suddenly hot to the touch and then blew! Now I don't know if the voltages are off from the actual brick adapter or the internal switch bank caps are bad. Has anyone with a channel F had this issue?

Using my dead CV, I used a heatgun instead of a solder iron to remove the chip and piggyback, and sound came back! So I swapped the chip and now sound works properly. Now I have a fully working CV and a parts donor. Thanks for the help!

Earlier on I damaged a colecovision with a green screen issue, this time I have another system with sound issues, and adjusting the RF pots while DK was playing showed no results. The sound issues consist of beeps during the start of donkey kong and no other sounds, this problem persists on the boot screen and on other games as well. However, I noticed that if I were to short pins 6 and 7 on the SN76489 sound chip, the sound comes back! Though there is some interference with the graphics, the sound comes back on with a bit of static and removing the short causes the graphics to clear up, but sound is lost as a result. Could a solder reflow on pin 7 of the chip or a check for a fault solve the sound problem?

Thanks for the advice, I'll take this as a lesson learned and try a lighter tip on the soldering iron and thinner solder.

FINAL UPDATE: Due to severe solder pad damage stemming from bad corrosion and efforts to backtrace the green screen problem going wrong, I will have to declare the CV's time of death at 1:08 PM CST. The main board and the case will be used for parts when I get another unit.

Update: After some corrections on my soldering, I was able to get a color screen (somewhat) however the pad for the video output came off, and soldering a jumper wire and some more soldering caused the green screen to come back. So I think I found the trouble area for the green screen.