-^CrossBow^-

As @Mitch stated all the Asteroids BIOS really allows for is the ability to load up all 7800 games PAL or NTSC. The normal BIOS will only play NTSC 7800 games due the encryption check. That encryption was not present on the European BIOS in PAL lands. I've never seen much point to the BIOS chip replacement and have only installed it on one client's 7800 as they purchased the kit and requested I install it. But I personally like the rainbow startup screen and 2600 games regardless of being PAL or NTSC will still load up on a stock 7800 the same way. The reason some of the Activison games don't always work was due to incompatibilities in the 7800 revisions themselves and isn't because of the BIOS.

This is a valid point, but I believe the reasons for the resistors in the first place is that the audio without the resistors would be too hot otherwise and the resistors are there to lower the amplitude of the signal. But you are correct in your thinking. If you really wanted to test it, you could do what others usually do with doing this mod. They take the pokey from the top where C10 is (Removing C10 in the process). As that is literally just the first via from the external audio line off the cartridge slot.

So if I'm reading this right, you have a 6k8 from both R5 and R6? Because if you were take the signal after R5 closest to the rear of the console, then you wouldn't get any pokey at that point. Both of the audio inputs route from the bottom of the resistors up to the poly caps and then into the RF modulator section. Eitherway, with only 6k8 off the TIA that is half of what the original circuit was using to keep the volume on it down next to the pokey. Granted it isn't nearly as bad as just taking the audio from before they hit the resistors as that is nothing but pure TIA driving the signal at that point but still. I actually use mil spec 1% resistors in the 7800 services I do. You have to read them though because they don't have color bands and are just brown colored resistor pills with their values printed on the sides.

I don't know...I've been stuck at 60hz only since forever and it doesn't bother me any. Then again, I don't play competitive online games either and only play the single player campaigns on FPS type games. As long as I'm getting my 60fps I'm good. But then again, I come from the generation where getting anything over 20Fps on Quake II was considered excellent when it was first released.

The reason is that if you don't have the resistors in place, you will get unbalanced audio volume between the TIA and POKEY audio. Taking it from the bottom of the resistors especially R5 means that you are taking the audio before the resistors and will result in the TIA audio overpowering the POKEY. When I do these kinds of installs, I clip the legs of R5 and R6 facing the rear of the console and then tie the legs together with a 10µf cap off the tied leads out to the audio jacks. If you leave the RF modulator in place and want it to work fully, then I actually solder in a second 6k8 and 18k resistors from the bottom legs of R5 and R6 and then tie the leads of the new resistors together followed by the filtering cap. Also to answer your last question. If you only have a 6k8 off of R6 and nothing from the POKEY, you will still have the TIA being louder in volume as compared to the Pokey. In a game like Ballblazer you won't notice this because that game only uses Pokey. But in Commando or another game that uses both, you will notice that the volume of the TIA sounds are much louder than the pokey. If that doesn't bother you then I guess your fine. But for most, it drowns out the pokey to the point where it is hard to hear the background melodies etc. that the pokey is providing.

Well, I've not used the official cables, but I did buy a set of the generic TOMEE branded cables a few years back. The results were aweful checkerboarding in the red hues. I've seen it before on cheap cables and since these cables had both composite and s-video outputs I had a sneaking feeling on something. Taking the cable connector apart where it plugs into the DC my fears were confirmed. The TOMEE cable was splitting the composite signal to the chroma on the s-video output! While that does technically work, it results in a non pure chroma signal and isn't the proper way to do it. Well the wires in the cable only allowed for either composite or s-video to exist so I cut the composite off and rewired the composite lead on the plug to the actual chroma output pin from the DC. That resulted in a really good s-video picture that I used as my main until finally installing the DCDigtal into it and going fully HDMI. So my point is to be aware of the cheaper cables because they are likely doing something similar and if you want to be sure to get the proper results, I would stick with the Sega branded ones or be prepared to have to modify the cable you get if you go 3rd party. Granted the TOMEE branded one is the only other one I've used and I also have one of thier VGA cables and that actually worked really well, but yeah just something to be aware of.

Just be curious if you had another PAL TIA on hand to swap it out with, if you still had the same issue? We know that different TIAs are out there and that later ones especially have issues. But you have what looks to be an early '81 produced TIA so I wouldn't think it would be a troublesome TIA.

Is this composite and audio only or? I'm asking because while it isn't quite 8, I do have an old JVC AV selector that has 7-inputs and handles composite and s-video along with audio on each input? 7th input is on the front however. Might be overkill for what you are looking for but I used it for years for my analog composite/s-video systems until I got my Extron. It is the JVC JX-S700. Here are the specs on it from the JVC support page. Mine is missing both of the front covers and I do not have the remote. That is how I got it years like 10 years ago off ebay. It might be too big for your needs as it is basically the size of an AV audio receiver as it was designed to fit in with the rest of your audio/video stuff at the time. http://support.jvc.com/consumer/product.jsp?modelId=MODL003020&page=1

It is part of the extra timing circuit that was added in the later revisions of the 7800 and then removed again, in even later revisions. The cap looks like a resistor but is actually a banded ceramic cap and usually green in color. If present you will find it in the dead center between two small 74x logic ICs in the right hand center side of the board. It seems to only affect the timing of the video since the actual game logic isn't affected by removing this. It is the cause of scrambled screens on most of the bus stuffing demos for the 2600, the cause for some of the activision games to not work etc. But again you can literally boot up a game that doesn't work with it enabled, clip the leg in real time and as soon as you do that the game screen comes up without a reset of the system. Put it back in circuit while up and running, and the game screen will go haywire again. But to get back ontopic in regards to TIA... @Andrew Davie, what brand of TIA are you working with here? I just posted something interested in my blog in regards to TIA issues between two different manufactures of TIA in a 7800 I discovered.

Had a pre-modded 7800 sent to me with a UAV that had good s-video but was producing some ugly jail bars in composite. But it was ONLY doing this on 2600 games. I at first suspected something in the wiring of the UAV or the UAV itself and first redid all of that and replaced the UAV. No change. It was then I started to look at things more closely and noticed that this '84 main board all socketed chip board appeared to have a TIA I'd not seen before. The company branding on it is IMP and it had a mid year 1988 date stamp on it indicating it was not likely original to the 7800 to begin with. Since I was able to disconnect the TIA color signal and get crystal clear black n white with the jail bars, I knew it had to be in the color signal. And since the UAV is tapping that signal straight from pin#9 off the TIA there was really only one culprit. I had another semi working 7800 with a more normal looking AMI branded TIA on it. Pulled that and put it into the socket on this troublesome 7800. Sure enough the jail bars are gone! I'm guessing this is a late revision TIA and it likely a CMOS part as it doesn't seem to heat up like most TIA chips do and it just feels a bit different. In any event...stay the hell away from these TIAs in and think about replacing them if you find them in your 2600s or 7800s. Especially if you plan to use composite upgrades or a UAV as it does produce jail bars. I also noticed that color trimmer has to be adjusted but a full 180 between the two chips. So there are some obvious internal differences in how they are designed and made. I've attached some pics to show what I was getting and between the two TIA chips. Here is the section about halfway on the edge of the ColorMatch screen on the Colorbar generator program. You can see the jail bars on the slightly different hue of green on the lower half. Upper half is fine. Here is the green purity screen with the bad TIA. Again, you can see the jail bars and while this is on green, they are present on all colors pretty much. Here is the colorbar screen from the bad TIA IMP branded chip. Again you will see that most of the colors exhibit noticed jail bars on them. It is quite distracting and unusual to see from a UAV board. Here is the actual IMP branded TIA chip that was causing the headaches above: Now here is the colormatch screen edge with the good AMI branded TIA chip. Here is the green purity screen with the good working TIA. Quite a difference here. Here is the colorbar screen on the AMI TIA. While there is still come color bleeding and other artifacts normal with composite on an LCD, you will see that the colors don't have the jail bars as they did with the other TIA chip. And of course, this is what the common AMI branded TIA looks like in most 7800s I've encountered: So if you have nasty jail bars from your composite video out signal, you might look at the TIA as the possible cause. Ivory Tower Collections

You are correct in that it does require it. In this case I'm using the Left+Right trigger as the Up+Down was causing the system to see a paddle controller in use. There are diodes installed off each input so they can't conflict with each other on the controller side or from the main logic side as only the NOR gate logic I used is able to see it and trigger the Pause function.

Well, what really bakes the noodle on this. Is that you can start up the parrot demo or any of the bus stuffing demos, you usually get scrambled lines on the screen. While that is happening, you can then switch C64 out of circuit, and it will instantly show you the demo without having to reset the console or any thing. That tells me that the issue is specifically a video output issue and not something on the main logic level of the code? If it were, it would require having to reboot the system after taking C64 out of circuit to get it come up right. You can literally enable/disable C64 while the demo runs to see the effect on and off.

I have mentioned this before, but I use the old Parrot demo to test bus stuffing on 7800s. Clipping C64 gets that demo and the others working each time. So not sure if that helps?

I got my order in. This will be the first Lynx game I've bought in a few years now I think?

It isn't terribly difficult to do this mod, but even with my equipment I've still had a pad or two just melt away with the rest of the solder when trying to remove the old ram even with my iron only set to about 300C, so you need a temp controlled soldering iron. That is why I recommended the clip the legs method and then remove the legs from the vias off the PCB after. As for other things to get, you might look at getting the ESD protection boards for the joystick ports. And if you don't want to mess with the 10sec delay startup on many games, get the bios update chip too.

Same here. The Parallax demo works but the other pokey demos just result in the clicking I spoke about before. Except for the Cybernoid450 file. That one just crashes the 7800 when I try to run it. Not sure it is signed with the encryption as I don't believe that one generates the 7800 rainbow logo.

Well on the previous ones I tried, I would just a clicking noise that was in beat with the music. But it was a single click and not multiples indicating that it was just one voice that I might be hearing something from. All the later made pokey demos like the dual pokey etc. seem to work. And some of the other ones did work but it is hit and miss.

I had a late model Samsung Tru-flat HD CRT. It was like a 32inch or something and was heavy as all get out! It had a really good picture but it did suffer from two issues I had with it. The first and most obvious was the convergence issues it had. There was a noticeable bow in the image along the bottom of the screen that I was never able to get sorted. Normal games you didn't notice it much, but when watching the news or anything with a scroller along the bottom, it would stand out. It wasn't able to handle light gun games. It had an issue where after a few min of being on, a noticed green and purple spots would form on the screen in the upper left and right corners. I was told this was due to the power supplies in those TVs not being quite adequate. The ONLY way to avoid these color spots was to literally turn the TV around as it was affected by the magnetic fields all around it. It did this at two different houses I lived in while I owned it and was a pain in the ass not being able to use the TV exactly where I wanted to in the house. Also the TV did have a built in degauss coil as you would hear it "grunt" when you first powered on the TV but as it only did it on initial power on, it didn't keep the spots from forming. Calls to Samsung support weren't helpful as they were the ones that told me to turn the screen to different directions to be rid of the spots. In general, the tru-flat screens just weren't that well regarded from what I would learn later on. It did have all analog inputs of coax, composite, s-video, component and not 1 but 2 HDMI inputs on it as well.

Do you just a clicking sound when trying to run them? That is what I got with the other versions released. But I'm not home yet to test these for myself until later.

Well as an example on the equipment I have. All of my RF consoles are a magnitude darker overall on my Sony LED/LCD in the game room. Some colors completely just aren't there when using RF. It was the main reason I first looked into AV upgrades for my classic consoles. I do have access to a few CRTs and even use a small 9" on my workbench, but for the bulk of my gaming, I wanted a larger display that I could use for both classic and modern systems. The ITC game room is pretty small compared to most so I always knew that trying to have both a decent size CRT and a modern flatpanel for high def stuff wasn't going to be possible. But as has been mentioned, with a UAV in place, I don't have these issues any longer through my setup and can keep the TV at a setting that works for all consoles at this point.

I also have all of those pics on hand as well of course. Most of my clients do not opt for the option due to the increased cost so it doesn't effect that many and even if it does, you can still use the original 7800 PSU to power the 7800 and a different PSU to power the DF cart and that will work fine. So It does require using two PSUs to do everything, but then everyone had a PSU for the 7800 already, and they already have to purchase a different one for use with the DF if they haven't one on hand so it isn't that big a deal. Newer versions of the DC-DC regulator I've been installing for over a year now do NOT have issue with the DF cart and work properly. The DF cart has a lot crammed into that case so it isn't any wonder that is requires power directly to it to begin with.

If you have cleaned the switch and tried different PSUs with the same issue, then it likely is the vram at this point. The service manual has a few different screen caps of various graphical issues that point to which ram module I believe. The more long term solution is to replace all of the vram with the +5 ram upgrade kit. But the traces on the CV, especially in that area are more prone to lifting than other parts. So if you do upgrade the vram, I would advise use of the clipping of the legs method and then using your soldering iron and tweezers etc. to lift the remainder of the legs out of the vias and go from there.

Because the hardware inside is only rated to take 9v max input from what Rafal advised me. That is why it needs to be a switching psu to ensure it is only kicking out 9v as anything over is likely to cause heatbuild up in the DF cart. This was also the reason why older 7800s I put DC-DC regulators into don't work with the power passthru from the DF cart. As the PSU on the DF is only 9v, it is only passing 9v to the 7800. But the DC-DC regulators I was using back then actually didn't kick in to +5 output mode properly unless the input voltage was more like 12v. Normal 7800 PSUs and other transformer PSUs put out over 12v without a load.

Was going to say I've seen this on modern displays but only through the RF side of things. Also the display itself matters as those with higher refresh panels will not have as much blur on motion as others. I could be wrong, but I know that Bob has an older AV mod in his personal 7800 for testing things so it is possible he isn't using RF output anymore to know about this being an issue or not.

These are two right off hand I know aren't working. This was after they had the NTSC encryption added to them so they would at least try and load up. They do but again I just clicks in time with the tune that should be playing. And this was happening on the 3 consoles I tested at the time.