I have a 150 watt, Univox 1561 bass amp with 4 x 6550 output section.
Circuitboard says 1061 but back of amp is labeled 1561.
Huge iron.
Current filter caps: 680uf/680uf/450uf/450uf/250uf
The whole amp was modded, probably in the 80's, the circuit board is a solder mess and parts hanging off.
Spliced wires everywhere. Does not power on.
I may be able to clean up the circuit board and reuse, or just roll a new turret board.
There is less room inside than optimal as the power tubes are installed as a "quad" in the middle of the amp.
I'm thinking of converting the amp to a stock Superbass/Superlead circuit.
Does anyone see any "gotchas" in the original power transformer?
I want to do a simple rectifier using the PT center tap.
Same for the heaters and bias supply, keep it simple.
I'll test the PT and OT and go from there.
The one has a Fan and half-power switch. I'll be leaving those out of the basic build, might add the fan back later.
Univox 1561 gut and rebuild, thoughts
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sonofmickel
- Posts: 118
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Univox 1561 gut and rebuild, thoughts
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Last edited by sonofmickel on Tue Jun 09, 2020 5:32 pm, edited 1 time in total.
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sonofmickel
- Posts: 118
- Joined: Sun Jan 13, 2008 4:56 pm
Re: Univox 1561 gut and rebuild, thoughts
This may end up being just a cool looking retro headcab project.
The 4 amp heaters look burned out and I think the OT may be a replacement and has spliced in 12ga solid core for the 2ohm lead and the ground(you can see the ground hook up on the first speaker jack). Notice the ground bus is "tacked" on the speaker jacks.
Some wild stuff going on in here.
1 Meg Treble pot, 50k Mid.
Pics of the amp:
The blue power tube heaters look fried. I'm stripping the circuit-board and retrace/blueprint it. May add all new tube sockets. I have been reading that they are cheap and prone to cracking.
Looks like lamp-cord was used to wire the heaters, replace that too. Redo rectifier, do those old diodes go bad?
Swapp them anyway, cost $2.
The 4 amp heaters look burned out and I think the OT may be a replacement and has spliced in 12ga solid core for the 2ohm lead and the ground(you can see the ground hook up on the first speaker jack). Notice the ground bus is "tacked" on the speaker jacks.
Some wild stuff going on in here.
1 Meg Treble pot, 50k Mid.
Pics of the amp:
The blue power tube heaters look fried. I'm stripping the circuit-board and retrace/blueprint it. May add all new tube sockets. I have been reading that they are cheap and prone to cracking.
Looks like lamp-cord was used to wire the heaters, replace that too. Redo rectifier, do those old diodes go bad?
Swapp them anyway, cost $2.
You do not have the required permissions to view the files attached to this post.