Laney R5 Bass Combo repair

[Nick Odell]

Thanks to all who helped over the Trace Elliot combos: all three are now fixed and will go back into use at the start of the new term.

The Laney R5 is also exhibiting huge levels of mains hum but doesn't seem to be suffering from any dry joints like in the TEs. I'm suspicious about something that I think must be part of the smoothing circuits since although I haven't tried to trace the circuit the diodes I can see don't appear man enough for the job.

The device is on the heat sink at the top of these pictures

about the quality: not my Fujifilm nor my cellphone but my MP3 player took these)

I pulled off the red and blue spade connectors in order to test it with a meter. I presume it is a rectifier and I also presume that it shouldn't read zero ohms in both directions.

Am I on the right track?

Thanks,

Nick

[Bob Minchin]

Nick, The item is a thermal switch which should be a short circuit until such time as the heatsink becomes too hot, whereupon it will open and reduce/remove power to the circuit.

If you have an ac voltmeter, try measuring the amount of AC on the dc supply capacitors. There should be very little AC present. If there is, then maybe a reservoir capacitor has failed.

hth

Bob

[The Nomad]

Looks like a thermal 'fuse' which goes open circuit if the heat sink gets too hot.

Avpx

[Nick Odell]

Doh! Didn't think of that!

I'll give that a go tomorrow. Thanks very much.

Nick

[tony sayer]

In article , Nick Odell scribeth thus

No thats a BI-metallic thermo switch that will either open or close when a preset temperature is reached on that heatsink..

Similar to these here...

>Thanks,>

[The Natural Philosopher]

wrong

and I also presume that it

wrong

Its a thermal cutout, A 'relay' that opens at about 85C

If the rectifiers have gone its usually exploding main capacitor time. Or the fuse goes.

[Gazz]

"The Natural Philosopher" wrote

bloody ell TNP, have you swallowed a load of the pills wodney takes of something :)

[Arfa Daily]

Not as such ...

Freely downloadable schematics for quite a few Laneys here

[Nick Odell]

Nick

[dave]

That device looks like a thermal cutout switch to me.

[Alan Deane]

Capacitors dry out with time. Replace EVERY electrolytic capacitor in it with decent 105 degree ones from Panasonic or similar. I did this in a 1970's Technics 8080 amp recently and the end results were simply stunning, the best sounding amp I've heard in years. I was reluctant to return it to it's owner!

Alan.

[tony sayer]

We've been doing just that on a lot of older equipment we own and maintain and a very worthwhile improvement it is too!...

[super.red1us]

Hello guys, I wonder if you can help me with my problem I have a Laney R5 bass amp and the thing is that it stopped working (i.e the power red lamp is no longer ON) while doing my bass practice at home

I tried switching cables and other power outlets but still no good

How can I fix it? where do I need to start checking? I'm supposed to keep rehearsing with my band for a couple of weeks and I can't afford to buy a new one.

Regards, Redwan

[GB]

The sensible advice is to take it to somebody who can fix it for you.

You could open it up and check whether there are any fuses inside and whether these have blown.

[tabbypurr]

the power red lamp is no longer ON) while doing my bass practice at home

rehearsing with my band for a couple of weeks and I can't afford to buy a new one.

You should have continuity from mains plug live pin to the live tag of the transformer, and from neutral plug pin to neutral transformer tag. You need a multimeter (£2) and the clue how to use it. Failing that, try repla cing any fuses you find with the correct type.

NT

[tony sayer]

Try a post to uk.rec.audio theres Phil Allison on there, a bit of a lad well he is an Aussie, but he seems to do a lot of guitar amps but be aware that he can get rather septic and quickly when he's in a bit of a mood!

Understand that you pommie barsteward!!!

[GB]

Without wishing to be unkind to the OP, my impression was that he might not have that clue. Hence, I suggested the most basic checks and then getting someone else to fix it.

[tabbypurr]

evidently. But we all started there.

I still think he'd do better to go learn. If he does, he can then fix lots of things.

NT

[Brian Gaff]

Well logic rules. first, check fuse in plug. if duff, replace. If new one blows, is mains cable detachable. If so, try another. If still blows, then amp is buggered. If you have no idea of electronics, then take it to somebody who has. Chances are the internal psu has blown its rectifier and this short has blown a fuse in the low voltage side of the supply. It can also be one of the output devices, but in neither case is it easy to replace. Does it have a fuse in its speaker cable or is the amp built into a speaker? If the former its worth checking that fuse. Brian

[Andrew Gabriel]

One option would be to look for nearby Repair Cafe or Restart Party events. Take it along and someone will work with you on fixing it. Do take enough bits with you to test it (you wouldn't believe how often people turn up with no sound source, no leads, no speakers, basically no way to test whatever they brought along that needs fixing.)