| Author | Message | ||
     Pete Simpson (pete993) Username: pete993 Registered: 02-2011 |
Hi musicman lovers.This is my first post here so be gentle. I have a mm 210 sixty five with the 12ax7 in it. Problems I am having are as follows- Recently bought amp and was working perfectly for a few days then it wouldnt switch off (power light stayed on until I removed plug from socket) that I could live with. It then blew the fuse when I switched to hi power, changed fuse again and same thing blew fuse. Any help would be great. thanks, Pete | ||
| Mike Kaus (mm210) Username: mm210 Registered: 05-2006 |
Just sounds like the switch welded together and then shorted. I assume it blows the fuse immediately? | ||
| Pete Simpson (pete993) Username: pete993 Registered: 02-2011 |
Hi Mike, thanks for your reply. Yeah fuse blows immediately when switched to hi power. I played the amp for over an hour yesterday in the lo power setting and it was fine.But when I switch to hi power it blows. | ||
| Mike Kaus (mm210) Username: mm210 Registered: 05-2006 |
If you hadn't mentioned that it stopped turning off first, I would have maybe said it was the high voltage winding. I would investigate further though as to whether the high side is toast. You will probably have to check the trans and see if it's shorted. | ||
| Lars Verholt (lmv) Username: lmv Registered: 11-2009 |
If this is the old style setup with the hi-off-low switch connected to the power primary, the standby switch will help you troubleshoot it. On a working amp of this type, the glow of the tubes will be significantly brighter on 'hi' than on 'low' because not only the plate voltage but also the heater voltage will be depending on the switch setting. With the standby switch 'off' the high voltage winding is not enganged at all. So, if the fuse (which is on the primary) does not blow with the standby in the 'off' mode, you can be pretty sure the problem is in the high voltage circuit. Common culprits in the high voltage circuit include (but are not limited to): Bad plate protection caps and diodes, bad voltage doubler circuit rectifiers, suspect filter capacitors (100uF and 20uF). Of course, the output tubes could be the problem - but if they sound fine at lo power, it is less likely. On the other hand, if the fuse still blows with the standby switch at 'off', the problem may be in the low voltage supply lines (solid state front end supply and tube heaters). Cheers, Lars Verholt www.captain-foldback.com | ||
| Pete Simpson (pete993) Username: pete993 Registered: 02-2011 |
Thanks Mike and Lars, will take it to checked out tomorrow as its all to technical for me. Will keep you posted as it may help others. Cheers Pete | ||
| Pete Simpson (pete993) Username: pete993 Registered: 02-2011 |
Hi Mike and Lars, and all musicman lovers. Had my amp checked out today and have been told that the power transformer is gone so Im trying to source one here in the uk. Any help from uk would be great. Cheers Pete | ||
| Mike Kaus (mm210) Username: mm210 Registered: 05-2006 |
That's wierd that at first you just couldn't shut it off with the switch and now the high side is gone too.. I'm wondering if one caused the other and if the shorted transformer took out the switch. Hmmm. I'm sure that you can get a transformer through Mojotone, if nothing else. I think they had them available for a while. Don't know what the freight would be though. Also, Mercury Magnetics shows them on a quick web search, if anybody over there carries them. Here's their page. NOT CHEAP! http://www.mercurymagnetics.com/pages/ca talog/manufacturers/MM_musicman.htm | ||
| Lars Verholt (lmv) Username: lmv Registered: 11-2009 |
Mercury's part number MUSICM-65-P/E seems to be the correct one, however, it is most likely the second type made for the hi-lo switching to happen on the secondary side. Your amp tech should be able to make that work though as Music Man published a service bulletin to aid field techs in performing this particular repair. The document is available for download on this website. The surgery involves a bit of rewiring and swapping out the hi-lo switch for a double pole type (if not already so equipped). Best of luck! -Lars Verholt | ||
| Pete Simpson (pete993) Username: pete993 Registered: 02-2011 |
Hi Lars, I have traced a company in Germany who stock replacements. The best price is 139 euros, it just gives the chasis number as 2275-65. hope this is the correct one. The site is www.tubeampdoctor.com in case someone needs parts. They seem to supply a good few parts. Many thanks, Pete |