ColecoVision with Black Screen and Tone

[MMarcoux66]

I just got another ColecoVision from eBay. It powered up and worked perfectly. I took it apart, cleaned it and then installed the Ruggers DB-9 antistatic boards. Everything seemed to work. Then when I put the case back together, all I am getting is a black screen with a tone. I took the Ruggers mod back off, cleaned the switch and still black screen with the tone.

 

Tried different power supplies, no go. The Atari expansion work.

 

Did I kill it :(?

[Ikrananka]

The Atari expansion only uses the CV for power, clock generation and the video output around the RF module.  So, it basically bypasses virtually everything that the ColecoVision side of thing uses.  Yes, you may have fried something but without a logic probe / oscilloscope it's difficult to troubleshoot.  The fact that you get a continuous tone makes me think it's not the VDP (TMS9928A), or its associated RAM, as a failure of those wouldn't do that to the sound.  Perhaps it's something to do with the Z80 CPU being held in a halted state or perhaps the CPU has been fried.  Have you tried pressing the reset button on the console?  Do you notice any changes when you press it?

 

Do you have a multimeter?

[MMarcoux66]

13 minutes ago, Ikrananka said:

The Atari expansion only uses the CV for power, clock generation and the video output around the RF module.  So, it basically bypasses virtually everything that the ColecoVision side of thing uses.  Yes, you may have fried something but without a logic probe / oscilloscope it's difficult to troubleshoot.  The fact that you get a continuous tone makes me think it's not the VDP (TMS9928A), or its associated RAM, as a failure of those wouldn't do that to the sound.  Perhaps it's something to do with the Z80 CPU being held in a halted state or perhaps the CPU has been fried.  Have you tried pressing the reset button on the console?  Do you notice any changes when you press it?

 

Do you have a multimeter?

No changes when I hit reset. Yes, I have a multimeter. 

[MMarcoux66]

Think I am going to send it to Ruggers. I want to have one with all his mods and some are above my solder abilities :).

[Ikrananka]

Probably a good idea as this will likely need some detailed investigation.  My guess is you've either inadvertently created a short somewhere when installing the joystick port ESD boards, or perhaps fried one of the chips due to static discharge.

 

Would be very interesting to hear what Ruggers finds as I haven't come across this particular combination of symptoms with a CV before, i.e. black screens are common faults, but that combined with the constant sound is unusual (at least in my experience).

 

 

[MMarcoux66]

2 hours ago, Ikrananka said:

Probably a good idea as this will likely need some detailed investigation.  My guess is you've either inadvertently created a short somewhere when installing the joystick port ESD boards, or perhaps fried one of the chips due to static discharge.

 

Would be very interesting to hear what Ruggers finds as I haven't come across this particular combination of symptoms with a CV before, i.e. black screens are common faults, but that combined with the constant sound is unusual (at least in my experience).

 

 

Sure. Will report back. I am sending it off today.

[ChildOfCv]

6 hours ago, Ikrananka said:

Would be very interesting to hear what Ruggers finds as I haven't come across this particular combination of symptoms with a CV before, i.e. black screens are common faults, but that combined with the constant sound is unusual (at least in my experience).

The sound chip always has random values in its registers on startup and will therefore have some noise.  The first thing the BIOS does is silence the chip.  So black screen/constant tone is a symptom of no CPU life, or dead BIOS.

 

But most likely it IS a shorted data or address line, as both of those can interfere with running even basic instructions.  Data is most likely since those lines go to both of the input chips, while only one of the address lines does.

Edited July 21, 2020 by ChildOfCv