Valve amp goes quite after a while. Carlsbro Sidewinder.

[Jake Holmes]

Hello,

So basically, I purchased a Carlsbro Sidewinder off ebay for £30. The guy said it had this fault. But I decide that for an all valve british made amp for £30 is still a great deal.

So I cleaned all the connections and pots as it had been stood for several years. I plugged it in and worked fantastically for a few hours. I tried it again the next day and after 3 or 4 minutes it goes to an almost inaudible volume with a large amount of hum. So I checked online and saw that it may have been the valves? I bought a known working set and checked to see if it would make a difference. But still have the same problem?

 

So basically I know that it goes quite after a short amount of time and it isn't due to the valves! I have a basic understanding of electronics, but still training on my fault finding.

 

If anyone has anything they could share, that would help so much!

 

Thankyou so much!

Jake.

 

(Please find the schematics attached) lo

Carlsbro_Sidewinder_Schematic(1).pdf

Edited April 8, 2020 by Jake Holmes
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[Kiwi]

My first thought was valves too.  When was the amp last serviced?  The next possible issue might be the power caps.  They need replacing every 20-25 years or so.  The amount of hum you describe suggests it might be the caps.

[ezbass]

Yeah, sounds like it’s bleeding voltage somewhere. As Kiwi says, the caps would be a good place to start. However, please exercise extreme caution around the power caps, they can hold deadly voltages and need to be discharged correctly before any maintenance is attempted. You may already know this, but it bears repeating.

[Jake Holmes]

@kiwi

@ezbass

Cheers guys! That really helps, I'll investigate them and see if there is any voltage leaking. I'll make sure to take caution with the caps! I'm pretty certain its probably never been serviced and maybe stood for 8+ years from what the guy said!

I'll get back to you, once I've checked them out!

 

Thankyou again!

-Jake