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First time modding an Astrocade (and its not mine!)


marauder666
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Friend has an Astrocade in really good condition, and its up to me to get it usable in the UK.  He's had it years and never used it, due to worry about cooling, etc.  He hasn't seen it working at all.

 

I've had this a few weeks now, and have now started with the mods.

First of all, used an unknown 240V-110V transformer, tested output voltage, 111V. OK.  Plugged Astrocade into a Samsung LCD which I know can show a really bad NTSC RF picture, it shouldn't show anything in the UK really as the tuner isnt designed for US signals.  It works!! with very odd colours.   Turned it off within 30 seconds, it's not mine, I'm not risking any heat damage.

 

Remove top shielding, and the lump of aluminium on the data chip, that cant work as a heatsink with the ribbon cable tent over it.

Added heatsinks to all the 40 pin chips.

 

Recap. Some of the black tantalums were over 25% out of the rated value, so all those have been changed to new Panasonic electrolytic, did the electros while at it.

 

Tested again, still working, and the picture is better than the first test.  Guess it had some marginal caps.

 

Time for a video mod, the S-video one would have been perfect, but now unavailable, so I found a simple composite mod, made it on stripboard, and it works first time.  It does need the modulator installing the generate the chroma signals from the 2 colour signals, which is a bit annoying.  I'll trying pulling the modulator, I'll get a mono picture, but if the interference is gone, will disconnect the audio from the modulator, and hopefully that will cure the issue.  Wiring for the mod is temporary.

 

Tested a cartridge and it works fine too.

 

Any other advice will be welcomed.

 

P1070029.JPG

P1070030.JPG

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P1070033.JPG

P1070034.JPG

P1070035.JPG

 

Edited by marauder666
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35 minutes ago, marauder666 said:

Friend has an Astrocade in really good condition, and its up to me to get it usable in the UK.  He's had it years and never used it, due to worry about cooling, etc.  He hasn't seen it working at all.

 

I've had this a few weeks now, and have now started with the mods. [...]

 

Any other advice will be welcomed.

 

Nice work keeping that Astrocade going in the U.K.!  It's great to see this NTSC system working in PAL-land.

 

Currently, on the Astrocade discussion group, video mods are being discussed.  It would be nice of you to drop in over there (You'll have to sign-up to post):

 

https://groups.io/g/ballyalley

 

I'm curious, which composite mod did you use?

 

Thanks for sharing your pictures; they're great!

 

Adam

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50 minutes ago, marauder666 said:

Friend has an Astrocade in really good condition, and its up to me to get it usable in the UK.  He's had it years and never used it, due to worry about cooling, etc.  He hasn't seen it working at all.

 

I've had this a few weeks now, and have now started with the mods.

First of all, used an unknown 240V-110V transformer, tested output voltage, 111V. OK.  Plugged Astrocade into a Samsung LCD which I know can show a really bad NTSC RF picture, it shouldn't show anything in the UK really as the tuner isnt designed for US signals.  It works!! with very odd colours.   Turned it off within 30 seconds, it's not mine, I'm not risking any heat damage.

 

Remove top shielding, and the lump of aluminium on the data chip, that cant work as a heatsink with the ribbon cable tent over it.

Added heatsinks to all the 40 pin chips.

 

Recap. Some of the black tantalums were over 25% out of the rated value, so all those have been changed to new Panasonic electrolytic, did the electros while at it.

 

Tested again, still working, and the picture is better than the first test.  Guess it had some marginal caps.

 

Time for a video mod, the S-video one would have been perfect, but now unavailable, so I found a simple composite mod, made it on stripboard, and it works first time.  It does need the modulator installing the generate the chroma signals from the 2 colour signals, which is a bit annoying.  I'll trying pulling the modulator, I'll get a mono picture, but if the interference is gone, will disconnect the audio from the modulator, and hopefully that will cure the issue.  Wiring for the mod is temporary.

 

Tested a cartridge and it works fine too.

 

Any other advice will be welcomed.

 

P1070029.JPG

P1070030.JPG

P1070032.JPG

P1070033.JPG

P1070034.JPG

P1070035.JPG

 

With the RF shield completely removed (top/bottom) and all traces of the ancient "thermal paste" removed, I've never seen the need for heatsinks on anything, quite honestly. 

 

The whole problem with the RF shielding was that it was an afterthought - the case, motherboard etc. had already been designed without it, as is.  So it was never meant to have one (RF) in its design.  Plus no one ever revised it (much) during the Astrocade's lifetime.

 

If you're looking for a Composite mod that doesn't require the modulator installed (at least I don't think it does) contact Ken Lill.

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Sorry to be the bearer of somewhat bad news, but you really only needed the heatsink on the chip under the keypad wiring. By putting the heatsinks on the rest of the 40 pin chips, it makes it impossible to tell what the chips are if they ever get removed. Because they have different power supply pins, putting the wrong one in the socket can be bad. I could blow up that chip, and maybe some others, including the other VERY RARE custom chips.

As far as coloring goes, the modulator or an s-video mod needs to be attached to provide it. otherwise it will remain black and white as no color information is included on the video line. You need to put the R-Y and B-Y signals in the output. Any questions just ask.

Ken Lill

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The only thing I can think of that msay cause the audio interfering with the video is if the ground connection to the modulator box is not making good connection. The other thing is the modulator itself. If you have an old (sometimes rusty) moulator, they do weird things including color weirdness. The newer modulators have correct and brighter colors.

 Could you send me a copy of your hand wired board. Also, could you send me a picture of the bottom. There may be something there that is caosing the weird colors.

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https://ballyalley.com/documentation/misc_hardware_docs/Composite_Video_for_Astrocade_Morton/Composite Video Mod for the Bally Arcade Astrocade (1980)(Phil Morton)(Electronic Visualization Center).pdf

 

I’ll post the stripboard layout tomorrow.

 

do you want a pic of the underside of the pcb,  theres lots of little screws attaching it to the bottom shield and as its not mine, dont fancy taking it apart too often.

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4 minutes ago, marauder666 said:

https://ballyalley.com/documentation/misc_hardware_docs/Composite_Video_for_Astrocade_Morton/Composite Video Mod for the Bally Arcade Astrocade (1980)(Phil Morton)(Electronic Visualization Center).pdf

 

I’ll post the stripboard layout tomorrow.

 

do you want a pic of the underside of the pcb,  theres lots of little screws attaching it to the bottom shield and as its not mine, dont fancy taking it apart too often.

Dude, you built a Composite mod based on a design from 1980?!  Fantastic!!!

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I've been one of the noisier people in the Astrocade group looking for anything to upgrade me beyond RF - I don't care if it is RCA, S-Video, or Component. I've gone through two different S-video mods - one overheated, the other produced bad colors. Slightly different design to each board. Anything that works (for NTSC for me!) would be very welcome!

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10 hours ago, marauder666 said:

I'll save him the hassle as I knocked together the layout for him ;)

 

1045371561_BallyCompsiteMod.thumb.jpg.1d6b240efd36e4a7eca018c22838e95b.jpg

There's another one I think he's going to try out that he found also.

Edited by juansolo
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Had another play around today.  Heatsinks removed from the 3 40 pin chips.

 

Ended up using a FMS6400 video amp to make my own composite mod, its very untidy with bits hacked on, Juansolo is doing a neat layout.  Picture is better than the one above.  Must be the filtering is does.

 

Still got the interference, its not strictly related to the audio, on Gunfight, without starting game, the interference comes and goes every 10 seconds (maybe) or so. Might be related to unboard clocks.  Tried the shielded cable to my mod, still the same.

 

Here's a picture before the interference, and during.  Background colour is much more yellow on the TV.  Other than this, its quite sharp, and not bad at all really.  Zoom them up after getting the full screen image, its hard to see when smaller.

 

 

 

 

P1070037.JPG

P1070038.JPG

Edited by marauder666
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It's back together.  Don't think its possible to get rid of the interference, if it was my console I'd be more happy to start a bit of hacking around on the PCB, but its not.  Used the video mod with the FMS6400, checked output on a scope, when plugged into screen and the levels are fine.  It's possible the interference is caused by the 240V-110V step down transformer, it doesnt convert frequency to its 110V at 50Hz.  Maybe the filtering on the input is geared up for 60Hz filtering.

 

Both controllers work well, paddles not too jittery.  Gunfight is so good with the paddle control.

Ran it for 15-20 minutes with no video issues.  All cartridges work.

 

Sometimes it has issues on powering up, but pressing reset sorts it.

 

 

 

 

 

P1070047.JPG

P1070048.JPG

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7 minutes ago, juansolo said:

For what it's worth this one is not only fully boxed, it has the original Bally shipping box too! Needless to say, we were a little reluctant to do any destructive modding to this one given it's value!

I wouldn't worry: the Bally Computer System models are the most common of this line, but a matching serial # shipping box is always nice.  You could always reach out to Allen Schweitzer and see if he has a working spare motherboard, import and mod that one ?.

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