Little mark II issue

[swanbrook]

Hi guys
Any help here would be great. I use a LMII head and a markbass 4x10 4 omh cab. I play in a wedding band so it never anyway loud. Over the past few gigs I have noticed a drop in volume and tone and on Friday night it cut out in the middle of a gig. I turned it off and on and it came back at a really low volume and after a few minutes came back to a normal level. But the cut out a few minutes later.
I bypassed it and went straight into the desk for the last few songs.

When we finished I checked it and it was really hot and the fan was not working. So I opened it up to let it cool down. Played with the fan a bit and then plugged it back in and the fan came on. But I set it yesterday and left it on all day and the fan worked.

Do you think it could be an intermitten fan issue ? I only ever heard of a fan breaking completely not this. I am 300 mile trip from the nearest dealer so it may be a while before I can get it there.

I used a friends LMII head last night and the difference in tone and volume was amazing.

Also the fact that I am running it with a 4 ohm cab the whole time could that make a difference.

I just ordered a new head today and will only ever use this as a back up when I do get it fixed

[mybass]

[quote name='swanbrook' post='1056113' date='Dec 12 2010, 03:42 PM']Hi guys
Any help here would be great. I use a LMII head and a markbass 4x10 4 omh cab. I play in a wedding band so it never anyway loud. Over the past few gigs I have noticed a drop in volume and tone and on Friday night it cut out in the middle of a gig. I turned it off and on and it came back at a really low volume and after a few minutes came back to a normal level. But the cut out a few minutes later.
I bypassed it and went straight into the desk for the last few songs.

When we finished I checked it and it was really hot and the fan was not working. So I opened it up to let it cool down. Played with the fan a bit and then plugged it back in and the fan came on. But I set it yesterday and left it on all day and the fan worked.

Do you think it could be an intermitten fan issue ? I only ever heard of a fan breaking completely not this. I am 300 mile trip from the nearest dealer so it may be a while before I can get it there.

I used a friends LMII head last night and the difference in tone and volume was amazing.

Also the fact that I am running it with a 4 ohm cab the whole time could that make a difference.

I just ordered a new head today and will only ever use this as a back up when I do get it fixed[/quote]

A 4 ohm cab won't be hurting it especially as you aren't working at high volumes.
The fan seems a problem to check out but you say it is working now. Check there isn't any build up of
dust around the edges of fan blades. I have a LMK and LM 2, they never overheat even when I've been pushing them, especially in winter.
You mentioned your friends amp "sounded" much better so was you amp bought new or s/h.

Maybe check out all cables, speaker cables etc. too.

[swanbrook]

It was bought new about 3 or 4 years ago and had never even gotten warm. It was used about two years as the main backline amp at an open air festival, itwas on for about six hours and had some really loud and heavy band using it and still nevr got warm!
They are a fantastic amp normally and I just ordered the tube version.

By sounded better I mean it was full of tone and the normal warm sound I am used to. Over the last few gigs mine seem to have lost volume. I kept putting it down to bad electrics in the venues we where playing.

I gave it to a repair guy and he had it running all day yesterday and said it didn't overheat and the fan was working fine.

I mailed markbass customer care to see if they have any ideas.

Cheers dude

David

[chrismuzz]

I use an F1 head, and also have had it cut out on me once, luckily it was during a practice! Same issue as you described with the fan not working. What I do now is check the fan every time I turn it on. i'd say 1/3 of the time the fan does not come on, and I have to stick a key into the hole to flick the fan and encourage it to start working. No problems after that

It's a bit of a pain in the arse but if you check it every time you shouldn't have any more problems!

Edited December 12, 2010 by chrismuzz

[swanbrook]

Wow ! Sorry to hear it's happening to you too but I really was starting to think I was nuts. I wonder is there a simple fix, I might try to contact Peter murry and see if he has any help.
Thanks forthe help guys !
Dave

[JTUK]

As far as I can recall from other post on here, this is Markbass's shutdown circuit at work when the amp detects something is not right. I seem to remember a BC-er had this problem when the horn in his cab developed a fault and the amp shut down to protect itself.

It may be the fan or it may be something else. Keep this thread up the top and see who else chimes in or pm Pete Academy as he posted something on these lines..I do believe.

[chrismuzz]

Yeah I reckon it's definately the Markbass shutdown circuit. If the fan isn't working then the head is more likely to overheat, but thanks to that it just shuts it down instead of causing any actual damage Since I started checking the fan every time I use it I've had zero problems. And since I take the least time to set up out of anyone in my band it's not much of an inconvenience!

[lojo]

I brought a little mark II new last year, first time i used it it got really hot, fan was not working, I phoned the shop and it was hard to get them to believe there was an issue

They said they would have to send it back blah blah, I insisted and they exchanged it for a new one with no issues

[dave_bass5]

Im pretty sure i read that the fans are the same type you get inside a PC so it shouldn't be too hard to replace one unless the controller is faulty.
For what its worth ive gigged my SA450 most weekends on 2 hours + gigs and it gets warm but its never shut down.