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Old 31st Jul 2007, 11:00 pm   #34
Zelandeth
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Join Date: Jun 2006
Location: Milton Keynes, Buckinghamshire, UK.
Posts: 931
Default Re: Rigonda Stereo - Reviving the beast

I might have to try that X-ray trick actually. Got a decent camera and a tripod, so should be able to get the angles right.

Haven't had a chance to do much on this set this evening (was de-dusting the other five, decided when I had to wash my hands for the fourth time in twenty minutes that it was time to clean them!), but did have a poke around earlier.

There's definitely something amiss with the right hand amplifier board (looking at it from the rear of the chassis) or its feed. It's not doing a lot, and it's doing it in quite a muffled manner. My gaze is immidiately falling on the stereo seperation control, which when first touched was causing all kinds of wierd behaviour from the other channel. It strikes me that this should act like a balance control - but all it seems to do is turn the volume up and down on the good channel. I was hoping it might be something simple like a duff pot there, but they both vary smoothly between .5 ohms and a meg. So much for that theory!

Upon further investigation, both channels seem to work okay when they feel like it...but they seem to be mutially exclusive so far! With the stereo control out, one channel works...in, and everything seems to switch to the other side. Hmmm...I think the switch has to be regarded with suspicion there.

I have noted that the EL84's seem to run really rather hotter than any of the other valves in the set - but not being familiar with them, I don't know if this is normal behaviour. There's also a very slight blue glow inside the shielding in the valve, I know some valves do that, this normal for an EL84?

If someone could tell me how the "Stereo separation" control on the back is MEANT to work, I'd be most grateful. I'm also at a loss to explain the function of the key on the front marked "Band" which presently appears to act like a graphic equaliser preset for music...which is all that it might actually be!

So far however one thing has become clear. Receiving FM, even through the somewhat questionable tatty little speakers I'm using at the moment, this is going to be one cracking sounding set when it's done.

As you can see below, the chassis responded well to a good clean!
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Last edited by Zelandeth; 31st Jul 2007 at 11:08 pm.
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