Hoffman Amplifiers Tube Amplifier Forum

Other Stuff => Solid State => Topic started by: punkykatt on March 09, 2015, 12:48:31 pm

Title: Yorkville MP8DX startup problem
Post by: punkykatt on March 09, 2015, 12:48:31 pm

http://www.yorkville.com/downloads/servman/sm_mp8dx.pdf (http://www.yorkville.com/downloads/servman/sm_mp8dx.pdf)

Hey Guys,  the band I play with has a Yorkville MP8DX powered mixer that has been working fine for the past seven years I have been with them. A couple of times over those years I have cleaned all the pots and switches when the smoke tar/dust builds up making them act up. But, at the past two gigs when the MP8DX is first turned on all the mics had low power and were very distorted for several minutes in the mains and monitors and then by its self starts working normal.  This morning I set up the PA at our rehearsal hall and its working fine right off the bat????  If any of you guys have any ideas or suggestions to whats going on it will be much appreciated.  Thanks in advance. Punky

Title: Re: Yorkville MP8DX startup problem
Post by: PRR on March 11, 2015, 07:23:19 pm

> all the mics had low power

Why do you think it was the mikes, not something else?

There is a LOT of stuff in that box.

And the more I look at it, the more penny-pinching and scrambled design I see.

I think if you got 7 good years already, you "may* be pushing your luck. Yes, I have seen such popular-price products hang-in for a couple decades, and others quit much sooner.

Title: Re: Yorkville MP8DX startup problem
Post by: shooter on March 12, 2015, 09:03:27 pm

Quote

There is a LOT of stuff in that box.

That is an understatement!!  WOW.  If that was on my bench I would politely  decline working on it.  If it was my own, I'd leave it opened up on my bench, wait for it to "act up" then take a can of freeze and squirt each SS component in the "common" areas.  BUT I wouldn't do that if I had to replace a customers box cuz I broke something, fwiw

Title: Re: Yorkville MP8DX startup problem
Post by: punkykatt on March 13, 2015, 04:31:28 pm

Thanks for the replies Guys.  I will tell the band mates we need to get a new powered mixer or at least a reliable  backup.

Title: Re: Yorkville MP8DX startup problem
Post by: smackoj on March 18, 2015, 02:27:22 am

I think my first guess, and it's something you could check with confidence would be the power supply. If you have a reliable ESR meter you could check the main filter caps. Check to see if you have the recommended plus and minus voltage in the power rails. Also do a thorough visual inspect and look for the usually suspects like loose wires, connectors and poor solder joints. Check the jacks for good contact etc. The basics of trouble shooting kinda stuff.

 :icon_biggrin: