Marantz SR6013 Frustrating Protection Mode Issue.

[grif3000]

I have a Marantz SR6013. It failed after a few months blowing the output transistors in the Front Left channel of the 5 Channel Amp board. This was fixed by Marantz under guarantee. Two years later the amp (now out of guarantee) fails again & enters protection mode. I asked a couple of repair shops to have a look but they all said they would not touch it due to the time & expense involved.

I had a look myself & traced the fault to the Surround Left channel which had two blown Darlington transistors & six blown resistors on the 5 Ch Amp board. I replaced these & put the amp back together. The amp ran fine for a week until the same 8 components failed again on the same channel. I then suspected the speaker / wiring on the Surround Left channel so I replaced the faulty components again & cross-patched the speaker & wires with another channel. This time the amp ran ok for about three days & the same components on the Surround Left channel blew again indicating that the speaker / wiring was not the problem. I stripped the amp down again & thoroughly cross-checked all the components on the 5 Ch Amp board (just using a meter) but could not find any problems. I changed the same 8 components again & they blew again after around a week. The 5 Ch Amp connects to the Speaker Output board which only has a few passive components but includes a relay. Does anyone have any experience of the output relays failing?

Whilst the Marantz Amp appears to have a good build quality I have to question the value of the Protection mode which doesn't seem to work!

Any thoughts or suggestions on this issue greatly appreciated.

 

[dobrykamil]

Hi.
Did you use original Darlington output transistors and adjusted idle current per service manual?

 

[grif3000]

Hi,
Thanks for the reply. I did set the idle current as per the service manual. I got the transistors from a reputable supplier in the states & they appear to be original. I will however source some others & see what happens. Thanks again for your input.

 

[dobrykamil]

You obviously have problem somewhere else. Something is causing Darlingtons base voltage/current to rise too much. I've marked potentially suspected components, especially those 3 transistors that run quite hot. Don't bother testing them as they'll pass, just replace them.

 

[grif3000]

Thanks again. I'll take your advice & change these components. I'll let you know how I get on.