PAL Intellivision repair questions

[superrune]

Hi!

 

I am trying to repair my childhood Intellivision console, a PAL 3668 revision. It has been in storage for over 30 years, and I have not yet plugged it in and tested it. I want to inspect the board first, and see if there are any potential errors before running power through it. I have very little knowledge of electronics and soldering, so obviously I have some questions..

 

First, I found this component that seems to be leaking:

I did a search, and this seems to be a 4.000 Crystal Oscillator. Does that mean a 4Mhz crystal like this would be a valid replacement?

https://www.digikey.com/en/products/detail/ecs-inc/ECS-40-20-4X/827537

 

Here are photos of the board from the top and bottom:

The underside has these brown splotches that look like leaks as well. Should I be concerned about these too?

Should I also open the RF housing and inspect it?

 

Any help would be most welcome!!

 

Edited July 18, 2023 by superrune

[walldog1]

The brown splotches are the rosin seeping out of the solder over time, I believe. Just carefully scrape off the hard, dried rosin and finish cleaning with some ISO and a Q-tip or something else. These solder joints and every other visible soldered joint should be inspected and soldered if they look bad or have little solder left. Your board actually looks pretty good compared to the many Logic Boards I have taken apart.

 

The crystal could also just be coated with this rosin and not be leaking. Carefully clean and inspect to determine if the crystal is leaking and bad. These crystals seem to be very durable and rarely need replacing. But I have never taken a PAL Logic Board apart either.

 

It would also be highly recommended that you replace transistors Q1 and Q2, all electrolytic capacitors, and check the voltages from your power supply board. There are links on this forum to obtaining repair manuals, etc.

[superrune]

Thanks for answering!

 

I've managed to find a couple sites with repair manuals, but none with a PAL repair manual. Will the transistors and capacitors names match on an NTSC and a PAL machine? IF I had to replace the crystal, would that digikey part be a valid replacement?

[walldog1]

You should be able to read the capacitance values and transistor part number off of the parts. The board is similar but a slightly different layout than NTSC. In fact, it is a much neater layout than NTSC. The frequency portion for sure would use different parts than a NTSC board. Plus, your PAL board has 2 crystals, NTSC only has the one in the opposite corner of your suspect crystal.

 

Hopefully someone else will respond to this post.

 

Also, if you click the "follow this post", you will get an email notification whenever someone responds to this post.

[HunterZero]

As stated above, the soldering on these Intellivision boards can be rather messy - the brown stuff looks to be leftover rosin flux. It should clean up with isopropyl.
 

There are a few different PAL board revisions that can be found in model 3668 Intellivisions - you have one of the simpler single board revisions (there are versions with a daughter board for the PAL colour circuitry). While much of the logic is the same as the more common NTSC boards, there are differences around the colour circuitry and RF output. And of course the STIC chip is a different version (CCIR vs NTSC).

 

All electrolytic capacitor values should be clearly printed on the cans.

 

PAL boards do indeed have 2 crystals - the 4.000MHz (XTAL2) one is the system clock, the other crystal XTAL1 is for the PAL colour signal. These very rarely go bad, you should not need to replace them even as preventative maintenance.

 

I would verify that the power output from the power supply board are in spec, then try powering on the system. You should get around 12V across the 2 pin connector near the large capacitor at the back of the power supply, then from the rear pin of the 2 pin connector to the 5 pin connector, you should get 5V, 12V, an unregulated 16V voltage (will be around 23V at no load), 0V, and -2.1V. Be very careful with the 5 pin ribbon connector cable, and check it has continuity.

 

I have found the SHOEI branded electrolytics on the mainboards of these systems are quite reliable, but it never hurts to replace ancient electrolytic caps. It's a good idea to replace the large filter caps and the 7805 and 7812 voltage regulators on the power supply board too. The voltage regulators run quite hot and can fail.

 

Other than that, the main points of failure on these systems are ICs... The RA-3-9600, the STIC, the AY-3-8914 sound and the CP1610 can all fail, in order of how commonly they fail from most to least. Also look for burning around the Q1 and Q2 transistors. It's more likely to be these transistors than the crystal if your CPU is not running.

 

- HZ

Edited July 24, 2023 by HunterZero

[superrune]

@HunterZero Thanks for this highly informative answer. This is great help!

 

I will be ordering an axial cap set from console5. They also have the regulators and transistors, so I'll make sure to get those as well. Probably good to have everything ready in case.

 

Impatience/boredom caught me the other day, and desoldered the 4Mhz oscillator and threw it away... Very stupid thing to do! Learnt my lesson (I hope!)

 

The biggest issue right now is that the 5 pin ribbon cable from the power board split open, and the innards just pulverized! I've ordered some molex parts that I hope will take care of that. I found this thread, and will try to do the same:

 

I see this will probably take some time to repair. But I'll update here if I get this thing running or not.

 

Thanks for all the help!

Edited July 24, 2023 by superrune

[HunterZero]

I am not sure if they still have spares or are willing to part with them, but users Humblejack and -^Crossbow^- had spares of the ribbon cable at one point, if you wanted to keep it original.

 

https://forums.atariage.com/topic/258132-power-ribbon-cable-replacement/?do=findComment&comment=3950008

https://forums.atariage.com/topic/347605-intellivision-power-ribbon-replacement/?do=findComment&comment=5204614

 

- HZ

Edited July 26, 2023 by HunterZero

[superrune]

That would be amazing! I'll PM them and ask!

[sebouley]

I am in the same boat 

 

I’ve determined that I have no oscillation at all on the crystal on the video part 

also there is no schematic anywhere for the pal version ; so it’s difficult to be sure what additional components are used in this oscillator 

 

does anyone have a schematic for pal v3 ? 
 

my current feeling is that the stic is dead and doesn’t maintain oscillation on its crystal .