ISO: Univox U320 PB schematic

[darkhosis]

This would be a 1967 tube amp head by Univox, power tubes are two 7951. preamp/reverb/tremolo: 12AX7, 12AX7, 12AU7, 6AN8, 12AX7. My power transformer has 2 secondary taps of 390V and a solid state rectifier.

I've found some expired threads, but no luck. This is the predecessor to the U-1221, but the circuit was revised between models. Not the same amp. They may share the same faceplate but they're designed different.

I need the schematic because grandpa decided to snip a bunch of leads back in the 80's.

thanks!

[vintagekiki]

This would be a 1967 tube amp head by Univox, power tubes are two 7951. preamp/reverb/tremolo: 12AX7, 12AX7, 12AU7, 6AN8, 12AX7. My power transformer has 2 secondary taps of 390V and a solid state rectifier.

I've found some expired threads, but no luck. This is the predecessor to the U-1221, but the circuit was revised between models. Not the same amp. They may share the same faceplate but they're designed different.

I need the schematic because grandpa decided to snip a bunch of leads back in the 80's.

thanks!

There is no salvation from the horror.
You try to draw a schematic.

https://reverb.com/item/4883821-univox-u320

[vintagekiki]

Links to Univox & Unicord Schematics

http://www.vintageunivox.com/schematics.html

http://web.archive.org/web/20020323221120/http://univox.org/pics/schematics/misc/

https://www.schematicsunlimited.com/u/univox

http://schems.com/bmampscom/univox/

https://elektrotanya.com/showresult?what=univox

https://el34world.com/charts/Schematics/files/Univox/Univox_Schematics.htm

http://www.prowessamplifiers.com/schematics/univox/

http://4tubes.com/SCHEMATICS/Music-amps/Univox/

https://schematicheaven.net/bargainbin.html Find Univox

https://elektrotanya.com/showresult?what=unicord

https://el34world.com/charts/Schematics/Files/Unicord/Unicord_Schematics.htm

https://www.tdpri.com/threads/bias-a-univox-u320apb.314995/

http://www.marshallforum.com/threads/univox-amps.11863/

https://www.gearslutz.com/board/attachments/geekslutz-forum/264869d1322422349-wanted-univox-u-305r-schematic-u-305r.jpg
Univox U-305R

[darkhosis]

http://www.vintageunivox.com/schematics.html

http://web.archive.org/web/20020323221120/http://univox.org/pics/schematics/misc/

https://www.schematicsunlimited.com/u/univox

http://schems.com/bmampscom/univox/

https://elektrotanya.com/showresult?what=univox

https://el34world.com/charts/Schematics/files/Univox/Univox_Schematics.htm

http://www.prowessamplifiers.com/schematics/univox/

http://4tubes.com/SCHEMATICS/Music-amps/Univox/

https://schematicheaven.net/bargainbin.html Find Univox

https://elektrotanya.com/showresult?what=unicord

https://el34world.com/charts/Schematics/Files/Unicord/Unicord_Schematics.htm

https://www.tdpri.com/threads/bias-a-univox-u320apb.314995/

http://www.marshallforum.com/threads/univox-amps.11863/

https://www.gearslutz.com/board/attachments/geekslutz-forum/264869d1322422349-wanted-univox-u-305r-schematic-u-305r.jpg
Univox U-305R

I think I went thru just about all of these sites, but a couple I missed. Thank you. The U305R does have similarities

I think the tremolo and reverb tubes leads were cut to get more power out of the amp.

[g1]

This is a very dark thread.
Then again, perhaps "there is no salvation from the horror" is the appropriate response to someone called 'darkhosis'.

[eschertron]

This is a very dark thread.

Or maybe Google Translate is just really depressed today...

[vintagekiki]

I think the tremolo and reverb tubes leads were cut to get more power out of the amp.

Tremolo and reverb tubes do not affect on power out of the amp.

The amp is not serviced or repaired with old and worn tubes.
In your case, the power tubes (7951), the preamp and phase inverter (12AX7) must be new.

[vintagekiki]

This is a very dark thread.

There is no salvation from the horror is a term (slang) which show a some device in a horrible state (decides to snip a bunch of leads) should be return to the correct state.

[Leo_Gnardo]

There is no salvation from the horror is a term (slang) which show a some device in a horrible state (decides to snip a bunch of leads) should be return to the correct state.

Can't say I've ever heard that line before BUT I'm going to start using it now for sure!

As I survey my rooms, crammed with 45+ customers items awaiting repair, there is no salvation from the horror...

OTOH it's a gold mine, just gotta grab the pick & shovel, and get to work!

[darkhosis]

After an exhaustive search of all iterations of the univox amplifier family on Google, I found a "Rev B" version. It looks like the same power supply featured on the "D-Lab" youtube channel with a weaker (cheaper) transformer and voltage doubler. Mine does not, thankfully. It's clear that circuit revisions were fast and furious at the time.. I dont know if mods want to add this to the collection or not
https://drive.google.com/open?id=1OU...FfijrxKMrTnbBL