The sunn Forum
Sunn Musical Equipment => Q & A => Topic started by: Mondoefx on May 20, 2015, 08:19:08 pm
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I just picked up a Solarus over the weekend. The tremolo seems not to work but I can't be sure. Looking over the amp it has been messed with and I don't know where to start. I need some pictures to compare with what I have. Google is not much help. I have a schematic but am unsure if it is valid. Again Google. Any help would be greatly appreciated. I can post pics if anyone wants to see how bad it is.
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UPDATE: I was able to get some information and a useable schematic for my Solarus. What I found out is, the setup my Solarus has is the same a mod Sceptres. The parts and layout are the same as a Sceptre. I found a guy that traced out all the parts on his Sceptre and built his own schematic. I did a cap job on the head and corrected some of the parts that the guy I bought it from messed up. The tremolo is working!
Now to the problems.
I am getting hum when I turn up the reverb. I went through the head made sure the wires are twisted and routed away from everything. The reverb tank that came with the head was not original to the amp. I was able to get the correct one one eBay from Sunn Solos that some guy parted out. Switched out the caps on the trem/reverb pcb. Still have hum. I found out that the choke was replaced with a Fender one, with different impedance values. Going to switch that. I changed out the reverb in and out jacks, mine were damaged. Grounds are good there. I'm thinking it is the reverb transformer. I have only found one place that sells it. Anyone know where else to look?
Tremolo... it works... kind of. After replacing the caps on the trem/reverb pcb, the tremolo started working. I am not sure the controls are working correctly though. If the rate is at 0 and the depth at 10 it gives a night slow deep trem sound. As I lower the depth it seems to drop off. Samething happens with the rate, as I turn it up is speeds up, then after around 3 I can't hear it trem. Not sure what to do now.
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UPDATE: I found a bunch of mistakes the previous owner made when trying to repair the Solarus. They changed out resistors and put in the wrong values and mixed up a few resistors and put them in the wrong places. I corrected the ones I could identify as wrong and now I get no volume loss from the mid boost switch and have more volume then when I first turned it on.
Still trying to track down the reverb hum. I am at the point that I might just pop the rivets and clean all the connections to see if that works. If not then I might try to reheat the solder joints. Last option is replace the reverb transformer. Does anyone know the values of the reverb transformer? I could take that off the list if I knew what it should be.
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Cleaning never hurts. My Sentura II had a hum a while back. Turned out to be one of the large caps on the reverb board had gone bad and was leaking. Might be worth a look.
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I did a cap job on the head this past summer. Recapped the caps off the power, the can cap and the bias cap as well. I will take a look at the other caps on the board though. Thanks for the feedback.
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Reverb hum and general reverb weakness on a recent Solarus that I repaired was due to oxidation on the RCA jacks. If you haven't sorted it out yet, try cleaning connections on both the amp and tank very well.