M50 Shutting Off and with No Protect

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wesleyb420
Posts: 30
Joined: Mon Jun 11, 2018 10:13 am

M50 Shutting Off and with No Protect

Post by wesleyb420 »

I bought an M50 the other day that is in pretty good shape cosmetically. The PO said that nothing had been replaced and he didn't want to deal with fixing it. I hooked it up and it turned on fine. The problem comes when I adjust the gain up (past 30%) the amp just turns off. The green light just fades out with no protect light at all. I am going to replace the caps but wanted to see if I need to check anything else. Sorry for the low amount of details but those are the ones I have. Thanks in advance!
lilviper
Posts: 270
Joined: Tue Nov 06, 2012 9:30 pm

Re: M50 Shutting Off and with No Protect

Post by lilviper »

Id recap it before it sets itself on fire.
wesleyb420 wrote:I bought an M50 the other day that is in pretty good shape cosmetically. The PO said that nothing had been replaced and he didn't want to deal with fixing it. I hooked it up and it turned on fine. The problem comes when I adjust the gain up (past 30%) the amp just turns off. The green light just fades out with no protect light at all. I am going to replace the caps but wanted to see if I need to check anything else. Sorry for the low amount of details but those are the ones I have. Thanks in advance!
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wesleyb420
Posts: 30
Joined: Mon Jun 11, 2018 10:13 am

Re: M50 Shutting Off and with No Protect

Post by wesleyb420 »

I clearly stated that the caps are getting replaced. I took the caps off and not a lot of leaky ones (1). What would cause the amp to just cut out?
wesleyb420
Posts: 30
Joined: Mon Jun 11, 2018 10:13 am

Re: M50 Shutting Off and with No Protect

Post by wesleyb420 »

Last edited by wesleyb420 on Thu Aug 09, 2018 9:53 am, edited 1 time in total.
Silverhorse
Posts: 159
Joined: Sat Aug 06, 2011 1:18 am

Re: M50 Shutting Off and with No Protect

Post by Silverhorse »

Hello
the power supply fets (IRFZ44) and the 2 diode (SF163) are not bolted to the heatsink. If you didn't take out the screws yourself look no further...
Silverhorse
Posts: 159
Joined: Sat Aug 06, 2011 1:18 am

Re: M50 Shutting Off and with No Protect

Post by Silverhorse »

you also need to change the rail caps...
wesleyb420
Posts: 30
Joined: Mon Jun 11, 2018 10:13 am

Re: M50 Shutting Off and with No Protect

Post by wesleyb420 »

I took the screws out...should I replace the caps?
ttocs
the Floor Sweeping Hack with Golden Ears
Posts: 14783
Joined: Fri Dec 19, 2008 9:53 pm

Re: M50 Shutting Off and with No Protect

Post by ttocs »

caps def need to go.......
what else can I say I am a grumpy asshole most of the time.
wesleyb420
Posts: 30
Joined: Mon Jun 11, 2018 10:13 am

Re: M50 Shutting Off and with No Protect

Post by wesleyb420 »

Are we speaking about the rail caps? The other ones will be here tomorrow.
wesleyb420
Posts: 30
Joined: Mon Jun 11, 2018 10:13 am

Re: M50 Shutting Off and with No Protect

Post by wesleyb420 »

Does the shrink wrap on the rail caps indicate something? Got hot and slid down?
ttocs
the Floor Sweeping Hack with Golden Ears
Posts: 14783
Joined: Fri Dec 19, 2008 9:53 pm

Re: M50 Shutting Off and with No Protect

Post by ttocs »

means the caps are bad.
what else can I say I am a grumpy asshole most of the time.
wesleyb420
Posts: 30
Joined: Mon Jun 11, 2018 10:13 am

Re: M50 Shutting Off and with No Protect

Post by wesleyb420 »

Ok, so one rail cap tested bad. I took them out but I lost a solder pad in the process. From what I can tell, the solder pad does not have a trace on the bottom side. Is that pad just to hold it and the actual trace is on top? Can I just use the superglue method and re-attach it?

thanks for the help on this and please overlook the excess solder...I have not used the solderwick yet, just the sucker.
Attachments
Amp Macro-1.jpg
lilviper
Posts: 270
Joined: Tue Nov 06, 2012 9:30 pm

Re: M50 Shutting Off and with No Protect

Post by lilviper »

If you navigate to the how to section of these forums, there is a very good tutorial on the repair process, and a few posts under the stickys on how to repair the through holes. If i recall correctly pg used a 4 layer board? I could be wrong there. But broken is VIAs generally bad if not repaired...

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ttocs
the Floor Sweeping Hack with Golden Ears
Posts: 14783
Joined: Fri Dec 19, 2008 9:53 pm

Re: M50 Shutting Off and with No Protect

Post by ttocs »

there is a few ways to repair it. Its not hard to lift a via and loose it. I finally got a repair kit to make it easier and better looking but it was not cheap
what else can I say I am a grumpy asshole most of the time.
Silverhorse
Posts: 159
Joined: Sat Aug 06, 2011 1:18 am

Re: M50 Shutting Off and with No Protect

Post by Silverhorse »

wesleyb420
Posts: 30
Joined: Mon Jun 11, 2018 10:13 am

Re: M50 Shutting Off and with No Protect

Post by wesleyb420 »

Silverhorse wrote:take a look at this link:

http://www.phoenixphorum.com/viewtopic.php?f=6&t=11910
I did end up finding that after scrolling.

Can anyone verify that this is just a two-layer board, not a four-layer that someone mentioned above? I am not seeing any traces between the layers, just on the bottom and top.
Silverhorse
Posts: 159
Joined: Sat Aug 06, 2011 1:18 am

Re: M50 Shutting Off and with No Protect

Post by Silverhorse »

it's a two-layer board
wesleyb420
Posts: 30
Joined: Mon Jun 11, 2018 10:13 am

Re: M50 Shutting Off and with No Protect

Post by wesleyb420 »

Thank you, everyone, for the assist...everything works!!!
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