Odyssey Game Repair - Page 1
Forum section: electronics / repair

author: Did somebody say broken?
author_rank: Newbie
timestamp: May 26, 2016, 10:01:08 pm
content: Our Odyssey game console from 1974, sat for 20 years or something in storage. Now it won't work and I don't have any repair history on it. I started with replacing the transistor for the voltage regulator, because there was no power coming out of it. That's fixed, but now I have a new problem. The tv can't get a signal from it. The summer card, the one that generates the video signal, gives me about 14 Khz. The rf oscillator with the summer card removed, is giving me a signal of 62MHz or so on channel 3, and 67MHz on channel 4, all correct. Most of that is lost in the traces to the rf filter, and get better again after the first capacitor in it. Then it goes through the coil and comes out of the cable jack looking like this with the summer card back in.Is the signal too weak? The schematic is attached.

author: rrinker
author_rank: Super Contributor
timestamp: May 27, 2016, 01:01:13 am
content: Have you checked the obvious in something that old, IE failed electrolytic capacitors?

author: Did somebody say broken?
author_rank: Newbie
timestamp: May 27, 2016, 05:09:06 am
content: I checked all of the caps in the RF circuit.

author: Shock
author_rank: Super Contributor
timestamp: May 27, 2016, 03:28:52 pm
content: I'm not sure what the signal level is, but old consoles and new TV's are a problem when auto tuning. Make sure when tuning set it manually to Ch.36 if possible and look for an analog only mode. Another trick is to put a known good console with an RF signal on the TV first and then tune that.

author: Did somebody say broken?
author_rank: Newbie
timestamp: May 27, 2016, 03:36:15 pm
content: I did put the TV on analog only mode and manually set it to channel 3. Not 36. Was that a typo? I don't have a known good console. I don't really want to buy one either as I don't need two. Thanks for the comments guys.

author: Shock
author_rank: Super Contributor
timestamp: May 27, 2016, 04:55:38 pm
content: Channels 3 and 4 or channels 36, 37 or 38 used to be the ones to tune devices in on, it's been a while.

author: rrinker
author_rank: Super Contributor
timestamp: May 27, 2016, 05:09:19 pm
content: May have been different in Australia? RF modulators in the US pretty much universally offer an option for channels 2 or 3, or else 3 or 4, because of the way the markets were divided up and frequencies assigned, no matter where you lived one of those would not have a nearby station broadcasting on. I actually lived about midway between two markets (Philadelphia and New York City) so depending on which way I pointed the antenna, I could get 3 from philly or 2 and 4 from NYC. Which I did quite often - only the NYC PBS station showed Dr. Who and Monty Python. Never interfered with my early game consoles, an early one similar to Odyssey which had the tennis and hockey variants, and later the classic Atari 2600.I do think the issue is more of one of compatibility with modern TV sets - do you have an older set around try this with, one that still has an analog tuner? People often give away old CRT TVs because they are effectively worthless but the relatively sloppy analog synthesis and possibly higher raw sensitivity of an old analog set may be what you need to get a clean image from this old game system. Shame, it was just a few weeks ago I sent the last such animal I had to the recycler. It was only a 5" B&W and the TV display was slightly fuzzy due to a mod I made back in the days when I knew some signals needed to be shielded but not exactly how to go about doing it in a foolproof manner - my first computer had an RF modulator that I couldn't get to work no matter what, so I opened this TV up and discovered the video and tuner sections were on two separate boards connected via a piece of coax, complete with RCA connectors on each end. Plugged the computer into the RF input side and the display worked great, so I got some coax and a SPDT toggle and cobbled on an RCA jack where the switch could select the source to be the tuner board or the jack I screwed to the back of the case. Worked great but probably broadcast a bunch of noise and it was somewhat susceptible to external noise. Completely analog set, would have been perfect for testing an old game console like this.

author: Anks
author_rank: Frequent Contributor
timestamp: May 27, 2016, 07:16:13 pm
content: Have you looked over the video section and ruled out the possibility of taking the video before the modulator. Maybe a composite or something that can easily be converted to composite.Just a suggestion

author: Did somebody say broken?
author_rank: Newbie
timestamp: May 28, 2016, 03:47:55 am
content: Cool Rrinker! No, I don't have an old TV around. I get no image at all. Just ant wars (the constantly changing black and white spots). Good thought Anks. That might work! I'll let you know how it goes.