Just bought a Coco 2, no signs of life

[zacht03]

Hello all, I just purchased a coco 2 in box for a good price on fb marketplace. Sadly, when going to test I receive no video. I checked my video cables and everything works with a C64 on rf so I opened the coco. When plugged in and powered on, none of the chips get warm at all other than U1, and it gets pretty warm (almost too hot to hold my finger). Using the service manual I tested the right side of R2 and got .88v. Testing Q1 I get 12.99v. Am I correct to assume U1 is bad and needs to be replaced? 

[Briza1]

Gidday mate,

 

when you turn on the machine, type in sound on and you should hear a click if it does then the unit is functioning some what. Which leaves it being the video output side

[Briza1]

13 hours ago, zacht03 said:

Hello all, I just purchased a coco 2 in box for a good price on fb marketplace. Sadly, when going to test I receive no video. I checked my video cables and everything works with a C64 on rf so I opened the coco. When plugged in and powered on, none of the chips get warm at all other than U1, and it gets pretty warm (almost too hot to hold my finger). Using the service manual I tested the right side of R2 and got .88v. Testing Q1 I get 12.99v. Am I correct to assume U1 is bad and needs to be replaced? 

Btw mate, join the coco facebook group

 

https://www.facebook.com/groups/2359462640

 

and someone in the facebook group can give you the link for discord group

 

[Briza1]

https://discord.com/channels/@me/1279765687392538697/1279766663696220225

 

this is the discord group for coco's. say7 that Briza sent ya

[zacht03]

Thank you very much for your replies. I actually just got approved this morning for joining the fb group. I will join the discord in a few hours as I am busy at the moment but I will also test that tonight with the sound on command.

[jhd]

12 hours ago, Briza1 said:

when you turn on the machine, type in sound on and you should hear a click if it does then the unit is functioning some what. Which leaves it being the video output side

 

SOUND ON is not valid Coco BASIC syntax. I suspect that @Briza1 is thinking of MOTOR ON (and MOTOR OFF) which will trip the cassette relay and thus make an audible sound. I am not aware of any other way to get a response from a Coco without a working AV connection. There is no internal speaker; all sound is routed through the RF modulator to the TV speaker.

 

In case anyone cares, the correct format is SOUND [tone], [duration] where both values are integers between 1 and 255.  

[zacht03]

Well I tried the motor on command when powered on and I receive nothing. This would confirm what I was thinking as the SALT chip (U1) is only outputting .88v on the 5v rail.

[zacht03]

@Briza1That discord link is not working for me

[Briza1]

On 9/2/2024 at 10:30 AM, zacht03 said:

@Briza1That discord link is not working for me

ok not sure why the link did not work. Hopefully you have managed to find the group in discord

 

[Briza1]

On 9/2/2024 at 9:24 AM, jhd said:

 

SOUND ON is not valid Coco BASIC syntax. I suspect that @Briza1 is thinking of MOTOR ON (and MOTOR OFF) which will trip the cassette relay and thus make an audible sound. I am not aware of any other way to get a response from a Coco without a working AV connection. There is no internal speaker; all sound is routed through the RF modulator to the TV speaker.

 

In case anyone cares, the correct format is SOUND [tone], [duration] where both values are integers between 1 and 255.  

Yeah sorry motor on was what I was thinking of. thanks for clearing that up mate.