My CoCo2 not only had garbage rf output, it also had a yellow bar issue AND the wrong artifact colors in hi-res mode! I ended up having to replace the 555 timer to fix the yellow bar, repair a broken trace to solve the color artifacting, and then eschew the RF modulator entirely for a decent picture (I used the Ed Snider drop-in board). Thank you for providing video proof of the CoCo 2's God-awful RF modulator!
You're welcome. I have only recently become aware of the yellow bar problem. Now I remember seeing it on one of my Cocos. It's surprising how many issues yours had in the video. Nice work fixing it!
Toldya! I knew it was a tuning issue somewhere! In the future however, you should use a non-metallic screw driver as not to mess with the magnetic field of the tunable inductor and especially tunable capacitors. They sell those everywhere. You should not need to remove anything, not even the cover.. that cover has holes in it where you can slip in a tuning device.
You are right there. Are those screwdrivers usually made of ceramic? In a pinch if I really needed something quick, a thin slice of old credit card may also work. I didn't sense much friction in the tiny threads.
@@acs8-bitzone651 plastic or ceramic...usually plastic those......it's not the friction on those adjustable caps.... those are extremely sensitive and should be tuned with a scope and other calibration tools. The chokes( inductors) are sensitive too but not as much. When tuning a cap, you want to use a very high precision LCR meter and scope. This way you can get that value very close. You can probably find a good meter for not too much and since you are doing this kind of work, it's well worth the price of admission.
@@acs8-bitzone651 They are usually plastic, very skinny and about 9in long. They are only a few bucks for an entire set with multiple heads and sizes. These were very ubiquitous in the days of TVs and radio repair, when RF coils had to be dialed in for proper alignment. Look on Amazon for "Philmore Anti-Static Radio TV Alignment Trimmer Tool Set Kit, 10 Pc"
Hey just wanted to say thanks for this video. My CoCo2 recently bought from ebay had this same b&w issue. I have the flat rf modulator in my Korean-factory-made 20261058 motherboard. Coco2 64k. My tunable inductor had glue on the top of it, I guess to PREVENT modification, so I removed that, and then turned it clockwise a bit to bring the color back. Any chance you can share your schematics of that modulator?
@@acs8-bitzone651 Thanks again. I recently removed my RF modulator because it was not operating great, replaced it with an 8-pin male header, and now I can plug'n'play other RF modulators (which work better) and can easily attached scope/logic analyzers for future exploration. You rock!
David, the S-Video looks quite good, and the composite, well it's about the same as the original RF output as far as clarity. Composite is not as sensitive as the RF modulator when you touch the case or move wires around, at least. I would say that if someone has a well-tuned RF connection with good cable, the composite mod alone is not a big upgrade. However, composite + s-video is worth the effort. Anyway, I'll try to show this in the new video.
ACs 8-Bit Zone Thanks for the update. S-Video would be great to hook up either to a TV or to my Commodore 1701 monitor with a cable to adapt to the RCA Chroma/Luma plugs. Do you think your mod could be adapted to work on a CoCo3?
I'm one of those new subscribers (did it yesterday) and yes it had something to do with septandy. I live in The Netherlands and Tandy wasn't that populair like the Commodore, MSX, Spectrum or Atari machines. Back in the day I thought that the CoCo was a computer which was more related to Amateur Radio, because the only place where they sold them was a store with old army stuff and amateur/cb radio things. Oh my was I wrong, if I knew then what I know now I would have buyed one (they weren't expensive). Another question, since I'm not knowing that much of the Tandy, but was it like the Spectrum in England was? They were the affordable machines compared to Commodore. I know nowaday a lot of people had C64 computers, but when they hit the market in 1982 they were expensive for a lot of people (and I'm not living in a third world country).
Tandy's were not cheap in England. In 1983 the Tandy Colour Computer 2 64k version was £279 just for the computer. You had to pay extra for a cassette recorder to load any games which was another £40. The joysticks were an extra £10. Games on tape were typically about £7.99. Cartridges more expensive around £19.99.
In our household there was a perception that the TRS-80 Color Computer was geared toward education and home productivity and the C64 was a gaming machine that could also be a computer. I can't recall how the pricing compared because both computers had a moderately high price tag initially and then curved downward after a couple of years. I was shocked to learn recently that at one time the Coco-2 and C64 were sold as low as $100 and $150, respectively. And the difference in price was probably because Coco-2 started at 16K and C64 always had 64K.
@@acs8-bitzone651 the memory could be indeed the difference in price (how stupid of me). From all available homecomputers back in the day the C64 was *I believe* the most expensive at the introduction. In the Netherlands only the computer was 1000 guilders. (no datarecorder or floppy drive) in 1982. A bit later you could buy MSX computer for 359,- guilders as a comparison (Canon V-20). After that Commodore dropped their prices
My CoCo2 not only had garbage rf output, it also had a yellow bar issue AND the wrong artifact colors in hi-res mode! I ended up having to replace the 555 timer to fix the yellow bar, repair a broken trace to solve the color artifacting, and then eschew the RF modulator entirely for a decent picture (I used the Ed Snider drop-in board).
Thank you for providing video proof of the CoCo 2's God-awful RF modulator!
You're welcome. I have only recently become aware of the yellow bar problem. Now I remember seeing it on one of my Cocos. It's surprising how many issues yours had in the video. Nice work fixing it!
Toldya! I knew it was a tuning issue somewhere! In the future however, you should use a non-metallic screw driver as not to mess with the magnetic field of the tunable inductor and especially tunable capacitors. They sell those everywhere. You should not need to remove anything, not even the cover.. that cover has holes in it where you can slip in a tuning device.
You are right there. Are those screwdrivers usually made of ceramic? In a pinch if I really needed something quick, a thin slice of old credit card may also work. I didn't sense much friction in the tiny threads.
@@acs8-bitzone651 plastic or ceramic...usually plastic those......it's not the friction on those adjustable caps.... those are extremely sensitive and should be tuned with a scope and other calibration tools. The chokes( inductors) are sensitive too but not as much. When tuning a cap, you want to use a very high precision LCR meter and scope. This way you can get that value very close. You can probably find a good meter for not too much and since you are doing this kind of work, it's well worth the price of admission.
@@acs8-bitzone651 They are usually plastic, very skinny and about 9in long. They are only a few bucks for an entire set with multiple heads and sizes. These were very ubiquitous in the days of TVs and radio repair, when RF coils had to be dialed in for proper alignment. Look on Amazon for "Philmore Anti-Static Radio TV Alignment Trimmer Tool Set Kit, 10 Pc"
Hey just wanted to say thanks for this video. My CoCo2 recently bought from ebay had this same b&w issue. I have the flat rf modulator in my Korean-factory-made 20261058 motherboard. Coco2 64k. My tunable inductor had glue on the top of it, I guess to PREVENT modification, so I removed that, and then turned it clockwise a bit to bring the color back. Any chance you can share your schematics of that modulator?
Great! See here for the schematic: drive.google.com/folderview?id=1iawKo8rM3PNL5g4nWRu-KFlnn0n_WJ4P
@@acs8-bitzone651 Thanks again. I recently removed my RF modulator because it was not operating great, replaced it with an 8-pin male header, and now I can plug'n'play other RF modulators (which work better) and can easily attached scope/logic analyzers for future exploration. You rock!
Thanks for this video, my Coco2 has the same issue
Glad it helped!
Looking forward to the S-Video mod in the next episode.
David, the S-Video looks quite good, and the composite, well it's about the same as the original RF output as far as clarity. Composite is not as sensitive as the RF modulator when you touch the case or move wires around, at least. I would say that if someone has a well-tuned RF connection with good cable, the composite mod alone is not a big upgrade. However, composite + s-video is worth the effort. Anyway, I'll try to show this in the new video.
ACs 8-Bit Zone Thanks for the update. S-Video would be great to hook up either to a TV or to my Commodore 1701 monitor with a cable to adapt to the RCA Chroma/Luma plugs. Do you think your mod could be adapted to work on a CoCo3?
I'm one of those new subscribers (did it yesterday) and yes it had something to do with septandy. I live in The Netherlands and Tandy wasn't that populair like the Commodore, MSX, Spectrum or Atari machines. Back in the day I thought that the CoCo was a computer which was more related to Amateur Radio, because the only place where they sold them was a store with old army stuff and amateur/cb radio things. Oh my was I wrong, if I knew then what I know now I would have buyed one (they weren't expensive). Another question, since I'm not knowing that much of the Tandy, but was it like the Spectrum in England was? They were the affordable machines compared to Commodore. I know nowaday a lot of people had C64 computers, but when they hit the market in 1982 they were expensive for a lot of people (and I'm not living in a third world country).
Tandy's were not cheap in England. In 1983 the Tandy Colour Computer 2 64k version was £279 just for the computer. You had to pay extra for a cassette recorder to load any games which was another £40. The joysticks were an extra £10. Games on tape were typically about £7.99. Cartridges more expensive around £19.99.
In our household there was a perception that the TRS-80 Color Computer was geared toward education and home productivity and the C64 was a gaming machine that could also be a computer. I can't recall how the pricing compared because both computers had a moderately high price tag initially and then curved downward after a couple of years. I was shocked to learn recently that at one time the Coco-2 and C64 were sold as low as $100 and $150, respectively. And the difference in price was probably because Coco-2 started at 16K and C64 always had 64K.
@@acs8-bitzone651 the memory could be indeed the difference in price (how stupid of me). From all available homecomputers back in the day the C64 was *I believe* the most expensive at the introduction. In the Netherlands only the computer was 1000 guilders. (no datarecorder or floppy drive) in 1982. A bit later you could buy MSX computer for 359,- guilders as a comparison (Canon V-20). After that Commodore dropped their prices
I add to others for an S-Video mod for coco2
Please check my other video at th-cam.com/video/tayGsz7Xs3A/w-d-xo.html and let me know if that helps out. Thanks for the comment.