Just got a coco2 and can't get a picture.

[+hloberg]

I just got a coco 2 really cheap from a thrift store and can't get a picture. It seem to be getting voltage on the board all the way up to the RF module but no picture. I get about 1.2v DC from the RF.

I get 9v AC from the transformer at two places it's connected to the board. All the solders look good, chips seated and nothing seems to be burned out.

I'm not familiar with the coco but I do know it's a 1st gen coco2 that had 64k installed.

Any ideas from you seasoned coco experts that might send me in the right direction?

FYI: I never had a coco when I was a kid (an Atari and TI-99 guy) but always was fascinated with them. I really would like to get this working if possible.

thanks

[BassGuitari]

Dumb question--and this is gonna sound condescending, but it's not meant to be, I swear!--but is the TV on the right channel?

(I ask because sometimes the simplest, most obvious solutions are the easiest to overlook. )

If that's not it, and everything looks good on the board, I suppose it's possible the RF modulator might be out of tune, though that seems unlikely. Do you at least get some static, or just nothing at all, like a blank black screen?

AFAIK the TRS-80 Color doesn't do anything special with RF output that any other system doesn't.

[JamesD]

LOL, I had the MC-10 I just purchased on the wrong channel when I tested it.
The switch is on the bottom and I accidentally flipped it when hooking up the power.
It took me a couple minutes to figure out what had happened.

[JamesD]

Are you using a matching transformer to input the video into the cable input on a TV?

[+hloberg]

got it on right channel (tested using by 2600) and tested the cable.Now, I'm using a RCA cable straight to the coax using a RCA to coax adapter like I use on the 2600. Since a cable wasn't included is there a transformer or something on the TV cable I might be missing? All I got was a console.

this is what the adapter looks like. will it work on a coco?

Edited March 22, 2016 by hloberg

[JamesD]

got it on right channel (tested using by 2600) and tested the cable.Now, I'm using a RCA cable straight to the coax using a RCA to coax adapter like I use on the 2600. Since a cable wasn't included is there a transformer or something on the TV cable I might be missing? All I got was a console.s-l1600.jpg

this is what the adapter looks like. will it work on a coco?

That looks just like what I'm using. If it works with other computers/videogames, it should work with the CoCo.

[+hloberg]

That looks just like what I'm using. If it works with other computers/videogames, it should work with the CoCo.

blech! I was afraid of that. what I can't understand is everything is getting voltage so the power supply is at least putting out something. I'm even getting 1.2 v from the RF.

I guess more testing is needed.

[JamesD]

Ok, when you turn it on does the casette relay click?
It should also click once the machine is on when you hit the reset button.

If not, you probably have a bad PIA or SAM.
If the PIAs are socketed, you can try swapping them to see if anything changes.
However, the 6847 should be outputting something even if there is a bad PIA or SAM, even if it's just garbage.

*edit*
Double check the video cable to make sure it's good.

Edited March 23, 2016 by JamesD