Marantz 2270 Protective Relay?

[rs732]

I picked up a Marantz 2270 from a seller on CL yesterday. I asked the seller a bunch of question regarding if the unit had any issue. The seller claimed to be a tech and mentioned that the unit only needed the lamps replaced. This should of been the first red flag (a tech doesn't know how to replace fuse lamps?) The unit seemed to be in decent condition and was an early champagne model,and the price was fairly decent.

I'll cut to the point. I got home and connected the receiver to a set of JBL L100's and turned it on. As soon,as I cranked the volume to give the speakers a bit of a punch both channels shut off. I connected some other JBL speakers that I use as testers and the same scenario occurred. I turned up the volume and both channels shut off. The same thing occurred while just using headphones. In order to get the sound back on you have to power off the unit and wait a few seconds and keep the volume low.

I opened up the unit,replaced the lamps and sprayed all the switches and pots. The multi path button won't stay depressed,but at the moment thats not my concern.

Theres signs that units has been previously worked on. The volume knob feels a bit loose and has a globby soldering job. Also,the power switch was replaced and has an acrylic button. When,i opened up the unit i noticed there was a wire dangling over the muting control amplifier it looks like it should be screwed down to the board.

Does anyone have any advice on how to go about repairing this issue?

 

[runningdog]

The multipath switch is not supposed to stay on, it is a momentary switch by design.

Can you hear or see the relay clicking when the sound goes away, and just before the sound comes back? There is a speaker protection circuit and it may be doing it's job, which is to open or leave open the relay if the signal coming from either main amplifier could harm a speaker.

Many things can cause this. It could be as simple as the DC offset setting is way off, so one or both main amps are pumping DC into the speakers. DC offset is an easy adjustment if you have a voltmeter. There are several other possible issues. The first step is to isolate where the problem is.

Go to the back of your 2270. Turn off the receiver and remove one of the jumpers connecting the Pre Out to the Main In. Turn on the receiver. Only one channel will be working now. Turn up the volume and see if it cuts out as before.

Then remove that jumper and put the other jumper back. Repeat the test, this time for the other channel.

If the sound cuts out when you turn it up on one channel only, then that points to the channel having issues. If it cuts out no matter which jumper is in place, that opens up some more possibilities.

There are more tests you can do, with a pair of RCA cables and the Pre/Main jacks. But do the test above first.

 

[wlhd1610]

Please make sure the power is off whenever inserting or removing those jumpers unless you're using sacrificial speakers.

Bob