Rigonda Bolshoi - UK Vintage Radio Repair and Restoration Discussion Forum

theredhouseinn · 14th Nov 2018, 7:07 pm

A Regonda Bolshoi radiogram in for repair.
Has anybody got the tuning instructions for the auto tuning circuit.
All the paper and electrolytics were low resistance, one diode in the can was high resistance, replaced both with 1n60's.
The unit holds position on signal, but it will not seek when the lever is pressed either way.
Any help will be appreciated.
John.

Tractionist · 14th Nov 2018, 7:34 pm

Were they self-seeking? I'm not too sure - but I don't think that they were on the 'Symphony'

Chris55000 · 16th Nov 2018, 8:30 pm

Hi!

Is it the seventeen–valve version you've got?

I have an original circuit diagram with English annotation and a user instruction book I can scan but I'm away all weekend collecting a transformer from Ed Dinning, but if you bear with me I'll get onto this after I get back after the weekend!

Chris Williams

Sideband · 17th Nov 2018, 12:52 am

Quote:

Originally Posted by Tractionist

Were they self-seeking? I'm not too sure - but I don't think that they were on the 'Symphony'

The last time I saw one of these was in the 70's. That one had seek tuning...you could press the up or down tuning button and the tuning would tune to the next strong carrier and 'lock'. I assume it used the AGC as a reference to stop the motor. As I recall, the motor was driven by a couple of valves in a differential type circuit. If there was any tuning drift, the tuning followed the drift so acted like mechanical AFC. I think there was also a manual tuning control which you just turned like an ordinary tuning knob. You could feel the auto tuning 'pull' as you turned the knob.

theredhouseinn · 17th Nov 2018, 6:19 pm

Hi there folks.
I have the cct diagram and instruction book from the owner.
This is the 17 valve version including the magic eye.
This was made by the Regonda factory in Lithuania using Russian parts.
The Motor is controlled by a triode pentode. A signal from the final if amp via a 10pf is fed to the triode, the output from the anode is fed to the tuned circuits, 4 off, in a can, then to the pentode grid, the anode controls current through a winding on the motor.
When the seek lever is pressed the pointer moves in the designated direction but when the lever is released the pointer stops. I am working on the theory that the seek is initiated by noise off station, and when a station is received the if signal switches off the pentode and stops the motor.

Watch this space-----I will be working on this next week.

theredhouseinn · 24th Nov 2018, 11:32 am

Hi.
I have done more tests as follows:-
With the AT button in, one core causes the pointer to move either side of the of the station, so it is possible to accurately set the tuning point. Another core adjusts the burst of audio vertically on the square wave at the grid of the pentode, using one kHz modulation from the multiplex encoder. Adjusting this core does not have any effect on the station setting.
The other two cores in the can do not appear to have any effect at all.
I can go no further now until I can get the proceedure for adjusting these cores.
In 60 years I have never come across a system like this one.
Checking the stereo seperation, l-r and r-l, was 1dB, all the electrolytics in the decoder were leaky to some degree or other. Change them all and tweeked the 19kKz and 38kHz coils gave over 30dB seperation, not bad eh.
Apart from this tuning problem and checking the turntable when I get it back in the cabinet, the job is finished.
Any help, ideas, suggestions on the AT operation would be appreciated.
John.

Andrew2 · 24th Nov 2018, 11:46 am

We had a few of these (and the similar 'Symphony' in for repair and the self-tuning was quite disconcerting. Manually tuning with the knob felt quite normal (although a bit heavy) until you got into the edge of a broadcast, then there was a 'humming' felt through the knob and the tuning was taken over by the motor until the station was centred.

theredhouseinn · 24th Nov 2018, 6:13 pm

Hi Andy.
Perhaps I am assuming to much. I have got it to auto centre on stations.
I am assuming that when the lever is pressed in either direction, that the motor operated the pointer until a station was detected and then stopped and auto centred.
I have put it to one side at present to get on with other work.
I have looked at a few forums on the Rigonda, but no one seems to have any servicing data. I am wondering if a manual was ever produced.
My friend is Lithuanian, and when he goes back home again he is going to try and get the info from a dealer.
This could turn out to be a long job.
Is that your radio amateur callsign after your name? If it is you must be an old boy like me. I will be 60 years a member of the RSGB next year.
John.

Andrew2 · 25th Nov 2018, 1:03 pm

Hi John. A bit less of the old please! I'm 65 and got this callsign in 1984 after putting it off for many years.
Re the Rigonda. I honestly can't remember much about them, other than they were built like the proverbial brick out-house and of course the wrist-spraining auto-tune feature! I'd completely forgotten about the tuning lever and can't bring any more details to mind. I'll have a poke around on the internet, but no doubt you've already done that!

Aub · 1st Dec 2018, 11:07 pm

What Andrew2 describes, above, is pretty much how i remember the Symphony tuning working when I had mine back in the late seventies. I remember having a pink coloured manual, quite thin, about A5 size. I think there was a circuit diagram in there, but can't be certain. I remember it was rated as 4 w per channel, from a pair of push-pull Russian EL84 equivalents per channel, presumably triode connected, as 4w is not much for a pair of EL84s.

Wish I still had it.

Cheers

Aun

14th Nov 2018, 7:07 pm	#1
theredhouseinn Hexode Join Date: Jan 2013 Location: Kelvedon, Essex, UK. Posts: 273	Rigonda Bolshoi A Regonda Bolshoi radiogram in for repair. Has anybody got the tuning instructions for the auto tuning circuit. All the paper and electrolytics were low resistance, one diode in the can was high resistance, replaced both with 1n60's. The unit holds position on signal, but it will not seek when the lever is pressed either way. Any help will be appreciated. John.

14th Nov 2018, 7:34 pm	#2
Tractionist Heptode Join Date: Apr 2016 Location: Cheltenham, Gloucestershire, UK. Posts: 875	Re: Rigonda Were they self-seeking? I'm not too sure - but I don't think that they were on the 'Symphony' __________________ Red to red, black to black. Throw the switch and stand well back!

16th Nov 2018, 8:30 pm	#3
Chris55000 Nonode Join Date: Aug 2007 Location: Walsall Wood, Aldridge, Walsall, UK. Posts: 2,868	Re: Rigonda Bolshoi Hi! Is it the seventeen–valve version you've got? I have an original circuit diagram with English annotation and a user instruction book I can scan but I'm away all weekend collecting a transformer from Ed Dinning, but if you bear with me I'll get onto this after I get back after the weekend! Chris Williams __________________ It's an enigma, that's what it is! This thing's not fixed because it doesn't want to be fixed!

17th Nov 2018, 6:19 pm	#5
theredhouseinn Hexode Join Date: Jan 2013 Location: Kelvedon, Essex, UK. Posts: 273	Re: Rigonda Bolshoi Hi there folks. I have the cct diagram and instruction book from the owner. This is the 17 valve version including the magic eye. This was made by the Regonda factory in Lithuania using Russian parts. The Motor is controlled by a triode pentode. A signal from the final if amp via a 10pf is fed to the triode, the output from the anode is fed to the tuned circuits, 4 off, in a can, then to the pentode grid, the anode controls current through a winding on the motor. When the seek lever is pressed the pointer moves in the designated direction but when the lever is released the pointer stops. I am working on the theory that the seek is initiated by noise off station, and when a station is received the if signal switches off the pentode and stops the motor. Watch this space-----I will be working on this next week.

24th Nov 2018, 11:32 am	#6
theredhouseinn Hexode Join Date: Jan 2013 Location: Kelvedon, Essex, UK. Posts: 273	Re: Rigonda Bolshoi Hi. I have done more tests as follows:- With the AT button in, one core causes the pointer to move either side of the of the station, so it is possible to accurately set the tuning point. Another core adjusts the burst of audio vertically on the square wave at the grid of the pentode, using one kHz modulation from the multiplex encoder. Adjusting this core does not have any effect on the station setting. The other two cores in the can do not appear to have any effect at all. I can go no further now until I can get the proceedure for adjusting these cores. In 60 years I have never come across a system like this one. Checking the stereo seperation, l-r and r-l, was 1dB, all the electrolytics in the decoder were leaky to some degree or other. Change them all and tweeked the 19kKz and 38kHz coils gave over 30dB seperation, not bad eh. Apart from this tuning problem and checking the turntable when I get it back in the cabinet, the job is finished. Any help, ideas, suggestions on the AT operation would be appreciated. John.

24th Nov 2018, 11:46 am	#7
Andrew2 Nonode Join Date: Mar 2010 Location: Dukinfield, Cheshire, UK. Posts: 2,037	Re: Rigonda Bolshoi We had a few of these (and the similar 'Symphony' in for repair and the self-tuning was quite disconcerting. Manually tuning with the knob felt quite normal (although a bit heavy) until you got into the edge of a broadcast, then there was a 'humming' felt through the knob and the tuning was taken over by the motor until the station was centred. __________________ Andy G1HBE.

24th Nov 2018, 6:13 pm	#8
theredhouseinn Hexode Join Date: Jan 2013 Location: Kelvedon, Essex, UK. Posts: 273	Re: Rigonda Bolshoi Hi Andy. Perhaps I am assuming to much. I have got it to auto centre on stations. I am assuming that when the lever is pressed in either direction, that the motor operated the pointer until a station was detected and then stopped and auto centred. I have put it to one side at present to get on with other work. I have looked at a few forums on the Rigonda, but no one seems to have any servicing data. I am wondering if a manual was ever produced. My friend is Lithuanian, and when he goes back home again he is going to try and get the info from a dealer. This could turn out to be a long job. Is that your radio amateur callsign after your name? If it is you must be an old boy like me. I will be 60 years a member of the RSGB next year. John.

25th Nov 2018, 1:03 pm	#9
Andrew2 Nonode Join Date: Mar 2010 Location: Dukinfield, Cheshire, UK. Posts: 2,037	Re: Rigonda Bolshoi Hi John. A bit less of the old please! I'm 65 and got this callsign in 1984 after putting it off for many years. Re the Rigonda. I honestly can't remember much about them, other than they were built like the proverbial brick out-house and of course the wrist-spraining auto-tune feature! I'd completely forgotten about the tuning lever and can't bring any more details to mind. I'll have a poke around on the internet, but no doubt you've already done that! __________________ Andy G1HBE.

1st Dec 2018, 11:07 pm	#10
Aub Nonode Join Date: Mar 2005 Location: Nuneaton, Warwickshire, UK. Posts: 2,039	Re: Rigonda Bolshoi What Andrew2 describes, above, is pretty much how i remember the Symphony tuning working when I had mine back in the late seventies. I remember having a pink coloured manual, quite thin, about A5 size. I think there was a circuit diagram in there, but can't be certain. I remember it was rated as 4 w per channel, from a pair of push-pull Russian EL84 equivalents per channel, presumably triode connected, as 4w is not much for a pair of EL84s. Wish I still had it. Cheers Aun __________________ Life's a long song, but the tune ends too soon for us all.