Schematic diagram of Unison Research Unico

[Albertahifi]

Hello everyone,

I am a long time reader first time contributor hoping to rekindle this thread with an issue I am facing.

I own a Unison Research Unico Primo integrated amplifier. I have been running an upgraded Siemens 1960's ECC83 (12AX7) tube with great success [contemplating some of the Underwood Hifi mods but haven't ventured very far down the road yet]. I recently came by some Mullard ECC82 (12AU7) 60's tubes and after *inadequate* research thought that these could be experimented with....

I started the amp and it goes through a 30 second warm up cycle. Near the end of the cycle I heard a 'pop' at about 75 db. Now my sound is very jumbled (unintelligible) and intermittent. I am hoping it is just a blown fuse.

I am hoping to hear back from this group on advice as I work through this. My next step is to compare the tube specifications (will post here) and try to find the potential circuit. From the tube pinout I will try and trace back to the fuses and inspect those. I am somewhat worried that I will not be able to visibly observe the blown fuse.

According to manual there are:
F1, F2, = 1AT/250V
F3, F4 = 1.6AT / 250V
F5, F6 =6.3 AT 250V.

The value for the main fuses is:
6.3 AT / 250 for 100V/120 V main voltage.

Looking forward to hearing back from the group.

Thanks,

 

[PRR]

12AU7 is NOT a direct replacement for 12AX7 !!

Yes, in "classic" circuits like guitar amps the 'U' can replace the 'X' with a distinct loss of gain.

This Unico Primo is NOT a "classic" tube amplifier. It has transistors to do the heavy work. I do not know how the tubes and transistors interconnect; if a "wrong" tube could damage transistors.

The tubes probably do not "trace back to fuses". Fuses protect against fire; even very sick tubes do not directly start fires.

"Do not open the amplifier !
There are no user serviceable parts inside.
Valve replacement should be carried out using only valves of the same type and matched in pairs.
The Unico Primo uses one valve type ECC83 (12AX7)."

 

[Albertahifi]

It ended up being visible burnt fuse (F5) and now 100% again.

 

[Chickenwatt]

The squematics can be found on HiFi Engine site, the topology of this integrated hibrid design is very good but the construction is horrible, the designer minimun thought that this amplifier will never get damage, removing the amp board out is a mega nightmare, so garbage design that I had to repair it by unsoldering a mosfet and a couple of 1/4 watt resitors by the top side, I think their designer should go to Bryston to learn and improve the build in order for us technitians to dissasemble easier, my goodness.

 

[2266]

An externally hosted image should be here but it was not working when we last tested it.

An externally hosted image should be here but it was not working when we last tested it.

-
Does anyone know the unison unico opamp model I own? I tested the ad797 output DC is very large, opa627 noise ne5532 no sound thanks

 

[aceace262626]

I've seen my unison research unico primo .
fuse inside is :
2 pieces 5A.
2 pieces 1A .
2 pieces 1.6A .

can I replace the 5A fuse with 6.3A fuse ?

according to the manual F5, F6 = 6.3 AT 250V

Does anyone have change 5A fuse with 6.3A ?
Thanks

 

[as_audio]

Due to multiple requests here is the Unico "Service Manual".
For other Unison models and questions please send me PM.

 

[tiefbassuebertr]

what about the reliability and lifetime from the amp in post #1 (model "PRIMO" from the UNICO-series) ?
Service friendly or not ? Thanks for an advice.
https://www.stereonet.com/forums/topic/559007-unison-research-unico-primo-hybrid-valve-class-a-amp/
https://www.stereonet.com/forums/topic/562126-unison-research-unico-primo-int-amplifier-price-drop/

 

[AllenB]

Hello, please help with the circuit diagram for unison research unico 200 It is not possible to send or repair to another country

Please post in English.

Maybe you are having difficulty with Google automatic translate? It may not be correctly showing you the way it writes on the forum...

 

[as_audio]

As far as I can see Ilya requested a schematic of Unico 200 ?
Here it is, it was posted before :
https://www.diyaudio.com/community/threads/unico-200.348178/#post-6755947
Please report the problem here or in the other thread "Unico 200".

 

[Ilya1979]

Thank you, thank you very much, I've been looking for her for a year

 

[as_audio]

Good luck in repair, please let us know about the procedure, I never had to fix this particular model.

 

[limbast]

Hello all.
I need schematic of Unico Nuovo.
The scheme is available on hifiengine, but I can't register there because my ISP is blocked. Is anyone registered on this site? Please download the circuit diagram for this amplifier

Spoiler: Schematic Unico Nuovo

https://www.hifiengine.com/hfe_down...ch/unison_research_unico_nuovo_schematics.pdf

 

[as_audio]

Unico Nuovo Service manual here.
Please report the problem and repair procedure in this thread.

 

[limbast]

Unico Nuovo Service manual here.

Thanks!

 

[limbast]

The fault is as follows: The amplifier went into protection. -UP fuse blown. The output transistors are not broken. After installing the fuse, there is no negative half-wave in the left channel, there is practically no signal in the right channel, and when the volume level changes, the DC voltage level changes. After the repair is completed, I will let you know what the problem was.

 

[xman2005]

as_audio, you are a very kind person. Thank you for providing the schematic.

 

[erdimeter]

Hi all, I need Unico DM Service manual if you have please share with me. I need for some burned resistors on amplifier board.

 

[as_audio]

This looks like serious burnout - not sure it is advisble to repair the amp.
Unico DM service schematics here :

 

[as_audio]

The fault is as follows: The amplifier went into protection. -UP fuse blown. The output transistors are not broken. After installing the fuse, there is no negative half-wave in the left channel, there is practically no signal in the right channel, and when the volume level changes, the DC voltage level changes. After the repair is completed, I will let you know what the problem was.

Now, did you survive this repair ?