help needed Need help diagnosing problem with Intellivision 2609

[schozam]

Hi all. I've had this original Intellivision 2609 for years that has been broken since I got it. I have picked it up, troubleshooted it, put it back on a shelf, and repeated this cycle countless times and still don't know what's wrong let alone how to fix it. Just wanted to see if anyone knew something I didn't to point me in the right direction.

 

Symptoms: does not display anything other than static with some random colors here and there, unable to make out any picture, though static clearly changes compared to when system is off

 

Troubleshooting methods used so far:

- did the obvious to clean contacts and carts, adjusted contacts, make sure it's set for the right channel on the TV, pressed reset after starting console, nothing

- used two different RF cables with simple coax adapter, no NES RF adapter here since that seems to be a common thing people try to use

- resocketed chips on motherboard, nothing

- tested continuity on power supply, main ribbon cable from power supply to motherboard, and from where ribbon cable meets with board to the rest of the board circuit, all are good

- scanned for channels with console plugged in and powered on, colors did change somewhat as channels scanned, maybe some very weak signal is being received? may be placebo on my part since nothing is recognizable

- cleaned power switch with WD40, nothing

- checked inside of RF modulator and attempted to readjust contact point with cable incase plugging in RF cable over and over misplaced it somehow, nothing 

 

I haven't tested voltages on the power supply yet as I need to learn how to test voltages in the first place, but I was hoping that there was something I missed before I had to do that. Based on what I see on the TV when it's on, I feel like it's some kind of RF modulator failure. Any guesses? I can provide pictures if needed. Thanks!

[mr_me]

Tune the channel manually as autoscan might miss it.  Try setting the Intellivision to both channels 3 and 4.  Are you testing on a modern TV, try a second TV if you can.

 

Multimeters that measure voltage aren't expensive, no need to get a high accuracy expensive one.  The voltage test points are in the service manual.

https://wiki.console5.com/wiki/Intellivision#Voltage_Test_Points

[schozam]

3 hours ago, mr_me said:

Tune the channel manually as autoscan might miss it.  Try setting the Intellivision to both channels 3 and 4.  Are you testing on a modern TV, try a second TV if you can.

 

Multimeters that measure voltage aren't expensive, no need to get a high accuracy expensive one.  The voltage test points are in the service manual.

https://wiki.console5.com/wiki/Intellivision#Voltage_Test_Points

I should have made this clearer but I did tune it manually before trying autoscan and I have a cheap multimeter. I have two CRT TVs that I've been testing on. I don't understand how to read the voltage test point sheet yet but I will figure it out now to hopefully narrow it down better.

[schozam]

14 hours ago, schozam said:

I should have made this clearer but I did tune it manually before trying autoscan and I have a cheap multimeter. I have two CRT TVs that I've been testing on. I don't understand how to read the voltage test point sheet yet but I will figure it out now to hopefully narrow it down better.

I've now done the voltage tests according to the reference sheet. TP 1, 4, 5, and 6 are all good, while 2 is at 16v and 3 is at near 0v. I guess the best thing to ask now is if it's easier to replace these components (I can solder) or if I should replace the whole power supply board. 

[walldog1]

On 7/20/2023 at 5:29 AM, schozam said:

I've now done the voltage tests according to the reference sheet. TP 1, 4, 5, and 6 are all good, while 2 is at 16v and 3 is at near 0v. I guess the best thing to ask now is if it's easier to replace these components (I can solder) or if I should replace the whole power supply board. 

Look at the rear side of DC Supply board for any poor/bad solder joints. Did you test with the ribbon wire and Molex connector removed? They need to be removed for the DC voltage test points. Otherwise, your voltage findings would require replacement of 5VDC & 12VDC Voltage regulators. There is one 2nd test at TP6 where you measure with both ribbon wire and Molex connector connected to the Logic Board. I believe that "loaded TP6" value should range between 12.45 & 12.85VDC.

 

Beyond this, a bad IC chip, bad transistors Q1 & Q2, or an adjustment to the RF mod as someone in the past might have played around with these. Or a bad RF Mod. It could be so many things, but those seem the most common.  Also make sure your frequency is set at the proper reading.

[schozam]

On 7/21/2023 at 4:16 PM, walldog1 said:

Look at the rear side of DC Supply board for any poor/bad solder joints. Did you test with the ribbon wire and Molex connector removed? They need to be removed for the DC voltage test points. Otherwise, your voltage findings would require replacement of 5VDC & 12VDC Voltage regulators. There is one 2nd test at TP6 where you measure with both ribbon wire and Molex connector connected to the Logic Board. I believe that "loaded TP6" value should range between 12.45 & 12.85VDC.

 

Beyond this, a bad IC chip, bad transistors Q1 & Q2, or an adjustment to the RF mod as someone in the past might have played around with these. Or a bad RF Mod. It could be so many things, but those seem the most common.  Also make sure your frequency is set at the proper reading.

Welp, the power supply board voltages are fine after testing with out those two connectors plugged in. Based on the fact that I see colors when the thing is hooked up really makes me think that the RF modulator is bad, so I will focus on finding a solution for that. Thanks a lot for your help.