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Grandstand SD070 on the Bench

 
crustytv
(@crustytv)
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I've recently bought a a couple of 70's pong machines, this one I got last Friday for £2.50 at a local boot fair. Got around to it today, I found a .022 cap that had split in half so replaced it. When powered up it works but I cannot tune it any better than you see in the picture. Anyone have any ideas what the cause of the poor picture might be. I'm guessing something in the on board modulator, nothing jumped out at me I suppose it could be a leaky cap, but they are mostly ceramic discs I don't have a schematic one would be of great help.

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Topic starter Posted : 21/08/2014 7:09 pm
Anonymous
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Have you tried a different RF lead ?
Rob T

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Posted : 21/08/2014 7:48 pm
crustytv
(@crustytv)
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Hi Rob,

No as its fixed/soldered directly to the daughter board, on the main board.

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Topic starter Posted : 21/08/2014 8:13 pm
sideband
(@sideband)
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There is low gain somewhere. Check the RF output lead. They often had a hard time with kids pulling on them and breaking connections at either end. Make sure the TV you are using doesn't have a duff (low gain) tuner!

Otherwise if everything seems to check out OK, it looks like a modulator problem. Does it have a direct video output?

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Posted : 21/08/2014 8:35 pm
Anonymous
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the problem is people used to wrap the cables around the console causing breaks in either the RF or power lead .
Ps would you like an Atari woody to add to your collection?
Rob t

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Posted : 21/08/2014 8:47 pm
crustytv
(@crustytv)
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Hi Rob,

thanks for the offer, I'm not really collecting these just saw a couple at a bargain price and decided on the spur to be a kid again.

The Binatone, is a dog. It wouldn't power up, upon investigation I found a transistor in the power line cracked in half. Found a generic replacement, it now powers up but seems to be stuck in a state with continuous blipping from the speaker. The Grandstand I've had more success with and its working fine. Turned out my 76 colour portable does not like the console. put it on another TV and its working fine.

I called my lad down (11) from playing on his Playstaion/Xbox, he's never seen pong games, I thought he would scoff at its naff-ness, he was hooked, we sat in the workshop playing for ages.

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Topic starter Posted : 21/08/2014 11:05 pm
Terry
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... Turned out my 76 colour portable does not like the console. put it on another TV and its working fine ...

Chris, this might sound stupid but did you check the tuning? I imagine that the simple modulator chucks out lots of spurious signals and it's possible that you were trying to use one of them rather than the correct channel.

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Posted : 22/08/2014 2:26 pm
EmleyMoor
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Step 0: Try leaving the console on for an hour, and see if there's any improvement. If so, that may be a clue. If not:

First step: fine tuning, if you've not already tried this.

Second: RF lead likely at fault. First, try replacing the Belling-Lee plug with a new one. Cut the lead back about 3cm from the entry point to the old one first. If unsuccessful, cut the lead back as far as you dare from the console entry point and fit a Belling-Lee connector - for preference a socket, so a straight plug to plug flylead can be used. If still no good, open the console and fit a new piece of mini co-axial cable the other end of which has a Belling-Lee connector, and arrange any further flylead you need.

There were a few games consoles that were poorly behaved on colour sets, and some colour ones that behaved badly on monochrome sets... however, if yours fails to perform acceptably on either, it is at fault.

 

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Posted : 11/04/2020 11:32 pm
crustytv
(@crustytv)
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Posts: 10843
Posted by: @emleymoor

Step 0: Try leaving the console on for an hour, and see if there's any improvement. If so, that may be a clue. If not:

First step: fine tuning, if you've not already tried this.

Thanks for your good intentions however, Errm... this thread is 6 years old!

I just moved this old thread to this section as I remembered it, and thought it was now best suited to being in here rather than the workshop forum.  Also as I stated in the 6th post, (see quoted below) I found the fault and the console was working fine and still does to this day.

This is why some forums always lock old threads but I prefer to leave ours all open, it does sometimes result in confusion though if folk fail to notice dates. But as I said above and once again, thanks for your good intentions. ? 

Posted by: @crustytv 21/08/2014

The Grandstand I've had more success with and its working fine. Turned out my 76 colour portable does not like the console. put it on another TV and its working fine.

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Topic starter Posted : 12/04/2020 9:09 am