New Member, New Project, Here's my 400!

Gepetto

Gepetto

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#61
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Old 'Arn Enthusiast
#61
Danimal1969 said:
Yes, I did all that as well and actually just went back and rechecked them all. Those are all open.

I also went ahead and checked all the transistors on the board as best I could. I did find one that was faulty. The MPSA93 I'm holding in the photo is open from Base to Emitter. Base to Collector is ok and there are no shorts.

Could that open MPSA93 be the problem?
Click to expand...
Yes Dan, that will do it, the amp will usually sit on the plus rail if that happens with no other damage other than what might have happened to your speakers.
 
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Danimal1969

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#62
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#62
Gepetto said:
Yes Dan, that will do it, the amp will usually sit on the plus rail if that happens with no other damage other than what might have happened to your speakers.
Click to expand...
That's good to hear! Thanks for the help!

Just anot her quick question. What transistors from your board kits are interchangeable with the mpsa93? I'll borrow one just to test it out.

Dan
 
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Danimal1969

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#66
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#66
So I replaced the two mpsa93's with the 92's and put it back together. No DC on the speaker jacks and it sounds great again. I guess I better use this as my one warning.

Time to get some real work done to this thing.

And luckily, somehow, my speaker does not appear to be damaged.

Dan
 
laatsch55

laatsch55

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Halfbiass...Electron Herder and Backass Woof
#67
If an output would have shorted, youir speakers would not have fared that well. Your problem started in the input section of the board, not so bad there, time for a DC protect board....
 
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Danimal1969

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#69
Yeah, I actually already ordered the kit a while ago. Didn't come with wiring so I Pm'ed him about it. If I don't hear back I'll just go buy some wire. Anybody know for sure what guage I should use for it?
 
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Danimal1969

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#71
After my near miss, it's definitely time to get this rebuild started. I'm doing a quasi comp build and plan to keep the original back planes. New control board kit, bulk caps, drivers, and dc protection. So here goes...

Spent two evenings getting the board mostly built. I'm happy with how it looks. I've hit the point of having my 1st question. Ready to start installing the transistors. Are there any special procedures for doing that? And should I be using heat sink paste on the heatsinks?
 
laatsch55

laatsch55

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#73
Smallest stuff first, IC socket right after the 1/4 watters. No heatsink grease on the TO-220's.. Looking good...
 
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Danimal1969

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#79
Thanks Ron. I'll for sure bring it down to your place when I get it done. Give it the full volume test there. :)

And thank you Joe. I hadn't realized that was the order of install. No matter, it'll go together just fine. Worst case I have to remove a few caps and reistall them later.

I'm pretty excited to be going on this.
 
Northwinds

Northwinds

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D9's are waiting Dan :toothy5:

They eat everything the M-504 can give them and just snicker. My Clair 700 is on the way to Perry for some lovin', bet they won't snicker when Sabbitha is hooked up... more like whimper like a scared dog hehehe
 
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