RCA connectors to Nivico console?

hexa

New Member
Hello, I hope someone can help me with this. I have a Nivico tube console receiver and turntable. It works fine but the problem is that it has no FM and also I don't want to use this turntable for my vinyls so I never use the console although I'd like to. I decided to take apart everything to clean it and I was thinking if there is some way to add RCA connectors for an FM receiver or CD player. Ideally I would like to put a separate switch, on=RCA, off=console selector. Can be done?

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Does this have a power transformer? If not, its not really going to be safe to use an external source with it. No transformer usually means one side of the power line ties to the chassis, and thats no good for use in other than its stock original configuration.

If it does, honestly the easiest way is to simply unplug the cables from the turntable and feed signal in there if you don't want to use the one it comes with. Or use a selector switch between the turntable and the input. Its probably ceramic cartridge, which is basically line level.

I would advise replacing those capacitors though. Japanese gear is known for terrible caps in the 60s.
 
Thank you gadget. Well, i didn't know that ceramic cartridges don't need a phono-pre so yes I'll do that with the selector switch as you say. Is there any de-emphasis circuit that will make the line-in sound weird? About the capacitors, I'd like to replace them but I don't know which ones.

(I only see these transformers, is it safe to add the line in?)

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The large transformer might be used as a power transformer, not totally sure. Is that transformer wired to the power cord?

Do you know what tubes this uses? Thats usually a solid clue about whether its likely to be a hot chassis set or not.
 
The power cord comes straight out from the chassis. Tubes: 30A5 (x2), 12AX7, 12AV6, 6AV6, 12BE6, 12BA6.

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hm, 30A5 and company usually indicate hot chassis design. I also see the little "pill" rectifier that is probably making the high voltage. I think I might be inclined to leave that one as it is.

The outboard transformer just puzzles me though. Maybe step up / step down power for the turntable motor? The other possible is that the power cord ties into the blue and white wire that appears to go to the transformer, and voltage comes back from the transformer. If its a real trafo that provides line isolation, you're golden. I think I'd really want to see a schematic for this to be certain, it could be an autotransformer that doesn't give any chassis isolation.
 
Unfortunately I don't have the schematic and have searched all over the internet without much success. I can't find any information for this console.
Is there any way I can test with the multimeter if it is a hot chassis or not?

Edit: Just checked, the blue wire from the power cord goes to power switch and the white goes to the transformer socket.
 
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where does the wire on the other side of the power switch go ? If both go to the transformer, you might be in good shape. Again, assuming its a real transformer and not an autotransformer.

an ohm check between the power cord and chassis would be a good first step. If you get no connection, thats promising. A second confirmation would be to ohm between the two wires going into the transformer and the ones coming back. If no reading, its not an autotransformer and you have isolation from the power line.
 
The other wire from the power switch goes to the turntable motor. I guess this ends my adventure with the console. I will assemble everything back and do a final ohm test between the chassis and the cord blades just in case.... Thanks a lot Gadget, I really appreciate your help.
 
absolute worst case you can just add an isolation transformer between the power cord and the wall and know that its not going to electrocute you. Always a handy thing to know.

Still warrants a re-cap too.
 
There is no continuity between the chassis and the power cord. I only find continuity between the power cord and one side of the transformer. Am I doing something wrong?
Which capacitors should I replace?
 
you may be good then.

Honestly I'd do all of the grey caps on the bottom and on the output transformers, the waxy looking ones, and the large can on top if it has one of those too.
 
I think I'll give it a go and see what happens. Yes, there is this big cap and also there is a lot of hum... Impressive, this amp is only 2x3.5W but is very loud! I will post when everything is completed.
 
Phase one completed. Changed all the capacitors with MKP (I have no idea if I did right about the MKP thing) and packed the can with three electrolytic Nichicon 57uF 400V instead of the original 3x60uf 200V. The amp is quiet now and I have better AM reception however the SQ is bad and I want to believe this is due to the AM. Next is to put these RCA connectors with an external source and check how it sounds. I have zero experience with tube amps so this is getting interesting although I know this amp is cheap really, so whatever.
Another thing is that it is impossible to access the capacitors to discharge them before tweaking with the amp. What can I do about it? Is it safe to turn the power switch on while unplugged and wait for few minutes?
 
Mostly it will self-discharge if you just turn it off. The power switch only cuts the 120v feed from the wall, the caps are still tied to the circuit so they will drain down. there should also be a connection from the caps to somewhere you can access. the output tube plates will do it if needed, they are connected through the output transformer. Use a resistor to discharge though, you don't want to fry the output transformers.
 
I turned it off, unplugged and left it overnight and next day the caps were discharged indeed. Now everything is done, I connected an FM receiver in the turntable line and it works just fine. This console is pretty loud for the 2x3.5W but the sound quality is bad. The high frequencies come out extremely harsh and the only way to listen to music is with the tone knob almost fully dimmed.
I don't know, maybe bad tubes, bad resistors? Anyway, I enjoyed spending some time with this 55 yrs old console.

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Could be some of both. Does the high voltage supply check out ok? If its a half wave rectifier off the 120 vac line I'm guessing its only going to give about 150 volts or so, but its worth making sure it does that. If the output tubes are toast it won't sound right. If the speakers have any sort of crossover cap, are they any good? You might be able to add some resistance to the tweeter to cut the highs back a little.

Also just possible its never going to sound amazing given what it is. Its a really nice cabinet though. If the stock electronics can't be made to not suck personally I'd be inclined to consider swapping something else in there. I can picture a lesser Fisher console pull in that hole, maybe something out of a Philharmonic or a Diplomat. Those were an all in one chassis receiver type thing, about 10 watts per channel. Not super powerful but they sound very good for what they are.
 
Yes, it is a beautiful cabinet, thank you. I think it's never gonna sound great and as far as I remember its sound when I was a kid it was bright anyway. I will connect a resistance in the tweeters and see how it plays and probably leave them connected. I would consider swapping another amp but there is no space inside and that would require major modifications in the cabinet. Also there is a Sony TA-1055 waiting to be fixed but that's going to be difficult for me because there is something blown in there and apart from some basic knowledge of electronic components, I have no idea how to troubleshoot audio amps. I think I will need the AK help again.
 
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