Mark III Issues Turning on

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conker985
Mark I
Posts: 22
Joined: Thu May 12, 2016 9:17 pm

Mark III Issues Turning on

Post by conker985 » Thu Sep 06, 2018 2:12 pm

So I have 2 Boogie Mark III's , one is a black stripe and the other is a blue stripe. I was playing on the black stripe one day and all of a sudden it turns off (the light would not come one). So I replaced the fuse and the light came on...turned it on still nothing.

Now my blue stripe. It turns on and I can hear the back of the amp and everything but still nothing.

Promethean
Mark II
Posts: 82
Joined: Wed Nov 13, 2013 7:53 am

Re: Mark III Issues Turning on

Post by Promethean » Fri Sep 07, 2018 2:33 am

Fuses blow for a reason. So its best to work why out before just replacing the fuse. I did have a power switch fail recently.

Faulty valves are invariably what blow the fuses in my Boogie.

Are the tubes glowing evenly with no hot spots/ hot smells.

Is there a hiss from the speakers when you turn it up?

Do you get a sound if you plug a guitar into the fx loop return to see if problem is just in preamp.

Happen on all channels?


Gotta give more clues.

xdg999
Donating Member
Posts: 159
Joined: Tue May 05, 2015 9:07 am

Re: Mark III Issues Turning on

Post by xdg999 » Fri Sep 07, 2018 4:11 pm

Have you tried replacing the Phase Inverter, which is V5. When they fail it produces the same symptoms your amps have. I had 2 fail recently in my Mark lll’s. Hope this helps.
Mark IIc+(Factory-HRx4,DRx2,DRG,HRG,KARG)(Upgrade-DRG,HRG,HR)Mark III+(DRG105,HRG105,DRGX101,SRG) Mark III DRG105,Mark V 25,Studio Preamp,50/50,1994 Dual Rec x2,Mini Rec

How many guitars and amps do you really need?

woodbutcher65
Mark III
Posts: 170
Joined: Fri May 04, 2018 10:36 pm

Re: Mark III Issues Turning on

Post by woodbutcher65 » Sat Sep 08, 2018 8:55 pm

Has the amp ever been recapped? It's old enough that by now it will be due for its second recapping at the minimum.

Electrolytic capacitors have a limited service life. Replace them every 10 years, or 15 at most. Or they can fail in such a way that will do more damage and cost more money to repair.

conker985
Mark I
Posts: 22
Joined: Thu May 12, 2016 9:17 pm

Re: Mark III Issues Turning on

Post by conker985 » Wed Oct 03, 2018 5:09 pm

I honestly do not know if it was ever recapped. It turned out to be an issue with my cab. The input where the speaker cable plugged into was bad and was fixed. However my amp tech was able to look over my black stripe and he cleaned her up good and got her working again.

woodbutcher65
Mark III
Posts: 170
Joined: Fri May 04, 2018 10:36 pm

Re: Mark III Issues Turning on

Post by woodbutcher65 » Thu Oct 04, 2018 11:58 pm

That amp has to be 30 years old now. Did your tech even look at the filter caps and read the date codes on them?

If he doesn't know to do that, or doesn't know what to look for, get another amp tech.


The caps are due for replacement if they're more than 15 years old. 10 years is a better answer.


There's a really good chance that they're original. Which means they're getting close to shorting out, spewing their corrosive guts all over the inside of the amp, and taking out a power transformer.

But with speaker jack problems, I'd be worried about the output transformer. If it got killed, then that would certainly account for no sound with the pilot light working.

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