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Old 11th Aug 2007, 5:43 pm   #41
David Goodall
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Default Re: Rigonda Stereo - Reviving the beast

I've been following this tale with interest, as I was given a Rigonda Symphony a couple of years back. It does indeed look to be, as Steve P describes "Serious kit." I was mightily impressed with the 15 or so valves, and automatic tuning. How for example would the sound compare with my Sansui 500 ?
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Old 12th Aug 2007, 1:56 am   #42
Zelandeth
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Default Re: Rigonda Stereo - Reviving the beast

That's another mighty impressive looking bit of kit. Obviously a higher spec unit than the one I have, but certainly from the same family. I have to wonder what those four red indicator lights on the front panel are for.

I don't know your Sansui, but I can state that even in its currently somewhat sick state using somewhat questionable cheap 1980s speakers, sounds really rather nice. Now, if only I could get both channels to work!

You need to get that one put back the right way up, and into service David!

PS: If it's the same cabinet material as mine, with nought other than a good clean and polish you'll find that it can double up in service as a mirror!
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Old 12th Aug 2007, 4:17 pm   #43
David Goodall
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Default Re: Rigonda Stereo - Reviving the beast

Yes, those indicator lights are a mystery. I've only just noticed the "band" control. I hope that adjusts the bandwidth as suggested, as I don't own a set with that feature. It should be fun to play around with.
As you say, It looks as though it will clean up well. Infact the varnish is so thick, I half wonder whether it was sailed here from the USSR !
I shall change the usual two caps, then test Steve's theory. It may be two out of two !
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Old 12th Aug 2007, 5:47 pm   #44
Steve_P
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Default Re: Rigonda Stereo - Reviving the beast

I've had a look at the circuit, and if the Volume and Balance Controls are on the input of the amps, then do the following:

1: Clean those switches thouroughly.
2: Clean the pots. They appear to be ganged together, but the same applies.
3: There's 2 x 47uf (I think) caps on the 1.0 pots - Change them.
4: There's the resistors and caps on the boards, linked to the pots. Check and Change.

Cheers,

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Old 14th Aug 2007, 11:34 pm   #45
RoundyMooney
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Default Re: Rigonda Stereo - Reviving the beast

Quote:
Originally Posted by David Goodall View Post
Infact the varnish is so thick, I half wonder whether it was sailed here from the USSR !
Quote of the week!

They do resemble earlier German offerings, don't they?
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Old 1st Sep 2007, 6:40 am   #46
Chris55000
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Default Re: Rigonda Stereo - Reviving the beast

Hi!

If the output valves are equivalent to EL84s the official published ratings were:-

Va 250V, Vg2 250V, Ia 48mA, Ig2 5.5mA, Rk 135 ohm, gm 11.3mA/V, Ra (Optimum Anode Load) 5600 ohms, Pout, 5.7W for 10% total Harmonic Distortion.

Heater 6.3V, 760mA, Max Anode Dissipation 12W

Most manufacturers used to under-run this valve a bit to economise on HT current and keep heat down, typically at Ia 34-38mA, Ig2 4-5mA with a bias resistor of 220 ohms. In my experience this still gave very satisfactory results.

Regarding the 0.08V positive grid volts, if you've replaced the grid-couplers from the previous anode(s), you should be fine, but watch out for "hot leak" in the output valves or signs of incipent "Grid-Emission". The set will almost certainly have parallel heaters, *so if you're careful*, you can remove the output valve from its holder and switch on, using your testmeter to see if there's still any positive grid voltage at the G1 socket contact - if it has now gone the capacitor is perfect as regards leakage, and you have one of the valve faults mentioned above.

I'd suggest -3 to -4V GB is much too low for nearly all 6.3V output valves, the EL84 and its equivalents are -7.3 to -8.0V, whilst the EL41 and the pentode section of the ECL86 which have identical characteristics, are -7.0V GB.

Older types, (ECL82 and the octals etc.,) needed -11.5 to -12.5V GB.

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