TRS-80 CoCo model 1 issue

[Ishiru]

Hello, i recently bought a TRS-80 CoCo model 1 (the gray one) with some cartridges for a very good price, but I've no image on screen and when I do an analogic channel searching my TV can't find anything so I guess it doesn't get any signal from the TRS-80.

The TRS-80's power supply does a sound when it's connected to the power (even when the power button it not on "ON"). When it's on "ON" the sound is still there but become different, I don't know if it's something normal or not. I checked the motherboard and power supply and everything seems to be OK at first sight, any melted capacitors or anything.

Also something that seems weird is the hook up cable. I don't know if it's normal but the part that hook up in the TRS-80 output don't fit very well and move easily.

Here is the part i'm talking about :

https://drive.google.com/file/d/0B3qrqUNdYbREbUJCSnhyNE8xMUk/view?usp=sharing

I also don't get why the core here is in plastic ...

And here is the part i hook up to the antenna input of my TV :

 

https://drive.google.com/file/d/0B3qrqUNdYbRER09yUERmV1JHeEU/view?usp=sharing

This cable doesn't seems to be the same as the Atari, Sega, etc ... one. The one i use for my Atari doesn't fit in the TRS-80 output.
Also, i saw on the internet something about a "channel select 4-3" switch on the back of the TRS-80 Color, but i don't have that on my unit. I just have a stickers with "Channel 36" wrote on it and a kind of potentiometer under it.

 

Does someone have a clue about how to fix it

Thanks .

[MarkO]

Your First Picture, that cable will only provide the Outside Shield... With no Center Conductor, it won't work at all...

 

 

You need a Cable with plugs more like the Second Picture...

 

MarkO

[Ishiru]

Yes i was thinking the same but it's the cable i received with the TRS-80, how is it possible a coaxial cable like that does exist without copper core ? Is it the wrong cable the guy sold me with ?

 

Also, a standard coaxial like the one i use for the Atari 130 XE, Sega, and cie doesn't work cause their core is too big to fit in the TRS-80 output, are there different diameter or something ? Which one should I buy ?

Edited September 25, 2017 by Ishiru

[Ishiru]

Hello, I tried with another coaxial cable that didn't fit perfectly in the TRS-80 Color output too (it moved easily), connected to on old rf antenna switch and this time my TV detected 2 channels but I had "snow" on both of them. + My tv started to blink like crazy when i was on these channels, i don't know why ... I had a signal even if the computer was on "OFF".

 

Also, i connected a coaxial cable with F connector to the TRS-80, it seems that the original one had an RCA connector, could it be the reason why it didn't work or is it the same ? I got a little electric shoke when I touched the shied of this F connector while unpluging it.

 

Can someone tell me which kind of Coaxial I have to use with this computer ?

 

Is it a way to test the video output of the TRS-80 Color with a multimeter or something without breaking anything ?

Edited September 27, 2017 by Ishiru