twowheeledwriter Posted January 27, 2012 Share Posted January 27, 2012 Hi - I bought a second-hand (but in mint condition) Laney RB4 combo a couple of years ago. I used it regularly for rehearsals and gigs over a period of 18 months. I then left the band and let the singer borrow it (and a bass) so that she could learn a bit of bass for a couple songs whilst the replacement bassist sang. Now the amp isn't working - I tried when I was due to stand in with band. It switches on, but only hums slightly and does nothing else - no lights or output. The singer swears that she didn't even use it or let anything happen to it. It looks in the same condition as when I left it with her. I trust her. Also, even though I was careful with it, I wasn't precious about it and gave it some rough treatment now and again - the odd drop and bump. Do you any of you have an idea as to what might have gone wrong? Any suggestions welcome. It wasn't the greatest combo in the world, but it did the trick when required. Quote Link to comment Share on other sites More sharing options...
icastle Posted January 27, 2012 Share Posted January 27, 2012 (edited) Assuming you've already tried substituting the guitar lead... I'd start with fuses. If you're getting a hum then the one in the mains plug is OK and the one in the mains socket on the back of he amp is OK, but there's usually going to be at least one more inside the amp that you should check... Edited January 27, 2012 by icastle Quote Link to comment Share on other sites More sharing options...
twowheeledwriter Posted March 28, 2012 Author Share Posted March 28, 2012 icastle - Please accept my apologies for not thanking you earlier for your suggestion - that was very rude of me. When I get my hands on the amp again (it's currently in another country) I will take a good look at the inside of it to check the fuses. Thanks again, tww Quote Link to comment Share on other sites More sharing options...
icastle Posted March 28, 2012 Share Posted March 28, 2012 You don't need to apologise for something that happened two months ago mate You're talking to a man who can't remember what he had for dinner two nights ago. Just let us know how you get on with the amp - it might help someone else with the same problem in the future. Quote Link to comment Share on other sites More sharing options...
twowheeledwriter Posted March 29, 2012 Author Share Posted March 29, 2012 I won't forget to pass on any news! Quote Link to comment Share on other sites More sharing options...
andersh Posted June 17, 2012 Share Posted June 17, 2012 Did you ever work this one out?! I have the same problem... I've opened it up but cannot find any fuses. Thanks! Quote Link to comment Share on other sites More sharing options...
hippopatimus Posted February 5, 2017 Share Posted February 5, 2017 (edited) Hey guys, its been a few years since anyone posted here, but I was having the same problem with my RB4 and was able to fix it. One of the 470uF capacitors (C25 on the circuit diagram) that supply the 15V rails to the pre-amp was blown and short-circuited. A quick replacement and everything was back to normal! Edited February 5, 2017 by hippopatimus 1 Quote Link to comment Share on other sites More sharing options...
Ralph Posted June 25, 2019 Share Posted June 25, 2019 (edited) Hi... I have a laney rb4 that just started acting funny..... While i was performing everything was fine and then it suddenly wouldnt produce sound from its own speaker..... The lights are on and everything.. But sound from the speaker cuts out and it just goes silent until i switch it off and on again..then it cuts out again... But it sends sound to the mixer without a problem.... But its internal speaker just dies out midplay.. Plz help.. Edited June 25, 2019 by Ralph Quote Link to comment Share on other sites More sharing options...
Pablo Salomón Posted November 8, 2021 Share Posted November 8, 2021 (edited) On 25/06/2019 at 16:27, Ralph said: Hi... I have a laney rb4 that just started acting funny..... While i was performing everything was fine and then it suddenly wouldnt produce sound from its own speaker..... The lights are on and everything.. But sound from the speaker cuts out and it just goes silent until i switch it off and on again..then it cuts out again... But it sends sound to the mixer without a problem.... But its internal speaker just dies out midplay.. Plz help.. A friend of mine brought this amp in a car and the inside connectors of the speaker became loose. I opened the front part of the amp and reconected and secured the cables. Done. I'm still having the same problem as the other guys here.. the amp swithches on, some lights are on too but it won't sound when connected to the normal or high jack. The backside 'FX in' works when using an active instrument. But it's passed directly to the speaker, it won't equalize or have any volumen or gain control at all. I will try with the fuses. Everything looks well connected and fixed, so maybe that will do the trick. Thanks! Edited November 8, 2021 by Pablo Salomón Mispelled Quote Link to comment Share on other sites More sharing options...
BassmanPaul Posted November 12, 2021 Share Posted November 12, 2021 Did you try the old favourite trick of linking the Send and Return of the FX loop with a short signal cable? Quote Link to comment Share on other sites More sharing options...
BassmanPaul Posted November 15, 2021 Share Posted November 15, 2021 I see I have responded to a zombie thread!!! It must be time for a nap 1 Quote Link to comment Share on other sites More sharing options...
www68 Posted January 16, 2022 Share Posted January 16, 2022 BassmanPaul - why does that trick from Nov 2021 work? I presume you just mean using something like a guitar pedal patch lead? (I have a generic type bass combo amp that I also trying to resurrect - i suspect fried power module, but will try any other trick too) Quote Link to comment Share on other sites More sharing options...
PigBass Posted January 16, 2022 Share Posted January 16, 2022 Hello @www68The idea is that the signal from your bass passes through the pre-amp stage in your amplifier and is then passed effectively via a pair of wires from the pre-amp to the power stage. The FX Send jack acts like a make break switch in that pair of wires, so in position 1 with no plug inserted, the signal is passed straight to the power stage. In position 2 with a jack plug inserted, the signal is interrupted and diverted via your effects cable through any effects and then returned via the FX Return Jack. If the FX Send jack is dirty or broken, the switch might be in position 2 but since there's no signal entering the Return FX socket you have no sound. Running a patch cable or any other instrument cable between the Send and Return FX sockets should eliminate a faulty FX Send socket. Hope that helps. 1 Quote Link to comment Share on other sites More sharing options...
BassmanPaul Posted January 16, 2022 Share Posted January 16, 2022 Same applies, if the amp has them, for pre-amp out and power amp in jacks. 1 Quote Link to comment Share on other sites More sharing options...
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