Intermittent Sound from a Peavey Renown Combo Amp

The Unbrokenstring Crew tracks down some intermittent problems in this wonderful Peavey Renown acoustic combo amplifier.  I think we know where to look, so let’s get to work!

The singer/songwriter owner of this amp uses both channels when performing in small venues

The unit is very clean inside and out.  See the Celestions where the Spiders used to be?

The power consumption label started a flame war in the blog-osphere.  Someone said that the power input requirement was the same as the audio power output.  Welcome to the Internet!

We will remove the chassis.  The loudspeakers are now disconnected.

The reverb tank is disconnected here.

Four big long machine screws hold the chassis in the cabinet.

This chassis is entirely shielded top and bottom!  You are looking at the bottom of the chassis.

The white clip holds the speaker wiring in place when assembled.

The chassis internals are exposed.  The audio power amp is rated at 120 watts or thereabouts, and the heatsink and power transistor setup reflects that.

Oops.  Where did this come from?  It was rattling around inside the chassis.

Front panel controls, from left to right.

One channel is called “Lead Gain” and the other one is labelled “Normal Gain.”

The equalization setup can affect both channels using the pedal-enabled ‘Automix’ feature of this amp.

The volume control looks OK from here, so we need to look at the solder joints on the bottom of the PC board.

While we’re working on this, let’s take some pictures to show where all the connectors go.

And we can take a look at everything to see if that loose nut we found earlier caused any electrical shorts.

These fuse holders are very loose.  I’ll change them out when I get the unit apart.

Another pic documenting where the connectors go.

All the knobs need to come off.

Now the controls need to be unbolted from the front panel.  One of my felt-covered sockets is at work here.

My only criticism of this unit is that the knob shafts are nylon, not metal.  But the PC board is free of the chassis.

The fuse holders were weakened over time, and one side came off of each of them.  All will be replaced.

I will use a little different style of fuse holder to get this unit going again.

We’re wielding the soldering iron like a boss today.

Here is a better view of the finished fuse holder job.

I believe that we are looking at the root cause of the failure.  Examine each of the solder joints for cracks.

These are fairly obvious.

I added a little solder flux to the broken joints, then removed the old solder entirely.

I’m moving down the circuit board and reworking all the cracked joints.  Many other joints were bad besides the ones at the PRE volume control.

In every case, the old solder is removed.  The original solder was probably work-hardened.  I don’t want to contaminate new solder joints with the failed material.

Let’s reassemble this thing and see how it works.

I’m particularly nosy around these power connectors.  That loose nut has me thinking that there MUST be some other arc and spark damage somewhere.

Fortunately, the Peavey engineers configured the connector pins on the circuit board and in the wiring harness in such a way that it is very difficult to incorrectly install the wiring harness.

I think that’s all now, folks.

Chassis is buttoned up.  A quick test shows that all demons are exorcised!  But I never found where that nut came from…

Here’s another happy Unbrokenstring Customer!!

Thanks for reading all the way to the end!

Contact – David Latchaw EE
Cell – 281-636-8626

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