Peavey Max 115 - No Output HELP!

[deluxe reverb92]

Hey,

First off, I don't post here too often, so thanks in advance for any help! :-)

I'm looking at a buddy's Peavey Max 115.....all it puts out is a fairly loud hum, and a very very weak signal.

So far I've checked the speaker, jacks, all the connections, solder joints etc... Past that, I really don't know what to check. Any suggestions would be great!

-Sam :-)

[WholeToneMusic]

Bleed any residual voltage by shorting out the main filter cap. Try hooking the negative lead of an ohm meter up to the center tap of the power transformer and then check all the ground connections to make sure they are close to Zero. Any high resistance readings should be re-soldered or tightened. Check for loose connections in the chassis, Look for any burnt resistors or other components near the power supply and elsewhere on the PCB. If a resistor is burnt you won't be able to read the color value. This should give you a good start. Power up the amp and check the filter capacitors to make sure they are holding charge with your meter.

[deluxe reverb92]

Sorry for the ridiculously delayed response!

Alright, so there's no burnt up components.

There's two fuses, a 3A and a 1.5A. The 1.5A was blown. When i replaced it, the amp made a scratchy sound for a second, then the fuse blew again.

The filter caps aren't shorted, and when i powered the amp up one read 20V and the other read 40V.

Not exactly sure how to do that test on the power transformer....on one side there's a black wire and an orange wire, and on the other side there's two orange wires, and a black wire.

Thanks again!

[Enzo]

If the filters are not shorted, then check the main rectifiers for shorted, D27,28,29,32.

After that, I suspect the LM3886 power amp IC.

Your transformer won;t likely blow the secondary fuse.

[deluxe reverb92]

Hey guys,

Sorry for the EXTREME delay here...this amp got put off for a while.

the only IC on the power board besides the 4560D reads "CA3080E"..... is that the same as this one: http://focus.ti.com/lit/ds/symlink/sn65hvd3080e.pdf

thanks guys!

[Enzo]

I don;t think that is true, That thing with 11 legs standing on the edge of the board is also an IC, it should say LM3886 on it. It is a thousand times more likely to blow fuses than a CA anything.


And for that matter, no, a SN65HVD3080E is not the same as a CA3080E. Google "CA3080" and the first couple hits are data sheets of CA3080. It is an OTA - operational transconductance amplifier IC. I sincerely doubt it is blowing fuses.

[deluxe reverb92]

heh.....right....I found it. haha.

thanks a million enzo! i just placed an order, i'll let you know how things go.

[deluxe reverb92]

Hey guys.....wow, this amp got put off for a long time! Happy new year!

So, i replaced that IC, and it still blew the fuse. What's next?

P.S. I really appreciate any and all help, even though im not that active on here!

[Enzo]

Replaced WHICH IC? My LM3886 or your 3080?

[deluxe reverb92]

the LM3886!

[Enzo]

Stay where you are, someone will be by soon to shoot you.

Does it blow fuses with no 3886?

You should have NO speaker connected until it can keep a fuse. Is your speaker connected and is it shorted?

Did we ever check the four main rectifiers?

[km6xz]

Hi Enzo
To save a lot of time and damage how about a sticky post at the top for minimum requirements for assistance. Like no load on a solid state amp until proven stable. A VOM or DMM as minimum test devices, and keep adding it it when an obvious condition it not met.
The speaker and fuse sellers much love the current fad of DIY amp repair. The tube rebranders are making a killing on every suggested first fix, for any symptom is replace $100 in perfectly good tubes.

[deluxe reverb92]

yeah, good thing, but they better hurry up or I'll do it myself!

word...no speaker is connected. checked the rectifiers already, and the filters are good, too.

I'm back at school now for a few weeks, so its gonna have to wait until I get home, but I will take out the IC and report back. I feel like maybe i got a bad one....how likely is that?

Anyway, thanks again for the help...will report back asap!

[deluxe reverb92]

ok guys....sorry again for the long lapse...haven't had much time to work on this thing in a while.

I replaced the 3886....and it stopped blowing fuses!

BUT. When I power it on, it hums loudly for about 30 seconds, then I am able to hear the instrument at very low volumes, regardless of the gain. Also, if i strum hard, for example, I hear the instrument loud and distorted like for a few seconds, before it returns to the near whisper volume.

WHAT THE HECK? I'm so lost with this one...