Little mark tube 800 - help needed

[A.G.E.N.T.E.]

Dear fellas, last night at rehearsal, playing with may little mark tube 800 and a MB new york 212 I noticed some weird noises coming of the speakers and the they kept moving even with no sound being fed. It sounded like wind or some fire burning.. Fortunately there wasn't any smoke involved. I disconnected the bass, changed speaker cable, power cable, restarted the amp.. Nothing worked. As I have another amp and set of speakers at the studio, I found out that the issue was the amp, as this issue was still happening with the other speakers. My description might be a little vague, but, does anyone have any idea what might be causing this. 

I forgot to mention that this noises still happen wen amp is muted. 

I'll try to post some video later. 

Thanks in advance. 

[Bunion]

I’m not overly familiar with these amps but I believe they have a tube and a solid state side, have you tried cutting out the tube side and just running on solid state, then the other, is it just one side causing the problem? 
if it’s the tube side causing the problem it could be the tube breaking down but try taking it out and reseating it. 
Does the sound have a hollow echo, if so the tube has gone microphonic. 

[A.G.E.N.T.E.]

1 minute ago, Bunion said:

I’m not overly familiar with these amps but I believe they have a tube and a solid state side, have you tried cutting out the tube side and just running on solid state, then the other, is it just one side causing the problem? 
if it’s the tube side causing the problem it could be the tube breaking down but try taking it out and reseating it. 
Does the sound have a hollow echo, if so the tube has gone microphonic. 

Yes, I tried that too. Both the solid state and the valve side sound the same. 

 

 

[Phil Starr]

Bad luck. I'm afraid MarkBass amps aren't really repairable at component level and MB don't supply any technical data to repairers making things doubly difficult. Their service, such as it is, is done by Real Electronics https://www.realelectronics.co.uk/repairs.html who essentially just do full board replacements at upwards of £200. To be fair their fees are stated up-front and you will end up with everything inside replaced so effectively a new amp

[BassBunny]

10 hours ago, Bunion said:

if it’s the tube side causing the problem it could be the tube breaking down but try taking it out and reseating it. 

I believe the tube is permanently soldered to the pre-amp board so removing/replacement is not possible.

@Phil Starr is correct in his summary as we've both been through trying to get MarkBass kit repaired.

These are the costs from Real from a few years back. I suspect they will have increased now.

£35 to diagnose the problem, which you get back if you go ahead. £69 fixed labour to repair, £18 courier fee to send it back + parts.

The "parts" will be whatever boards need changing.

[Bunion]

2 minutes ago, BassBunny said:

I believe the tube is permanently soldered to the pre-amp board so removing/replacement is not possible.

That’s a bit naughty!! 

[A.G.E.N.T.E.]

I can confirm the tube is soldered. I took a look to see if there was any identifiable problem. 

 Update: I dont think the issue is the tube. At least  it`s not going microphonic as i gave it some  light touches with no influence on the noise.

 

Edited June 25, 2022 by A.G.E.N.T.E.
Test update