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Support and repair information for Marantz home theater AV receivers and older audio-only receivers.

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Marantz SR4300 - No Display/Front Panel Dead

Hi guys!

Let me start off by mentioning that this a new hobby, and I'm still learning! I have successfully repaired more simple stereo amplifiers, and this is my first attempt at an AVR receiver. I picked this Marantz up at a junk shop for next to nothing, and thought I'd give it a go!

At first the unit would not power up at all. A few repaired dry joints later, and the amp now clicks into life, and all voltages, 15v, -15, 5v, 3,3v etc are present. I have also cleaned all ribbon cables and connectors.

What I can't seem to figure out: The front panel display is completely dead. I have checked the AC voltage at the connector and there is indeed ~4,5v there, as well as 3,3v and 5v.

Any insights would be much appreciated!

Thank you.

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Hi @swellenuwe

Check if there's 2.6V AC on the main board connector JFN701 pins 2 & 4, JFN702 pins 2 & 3 and front board JFF101 pins 2 & 3.

If both voltages get to JFF101 OK then if could be a faulty fluorescent tube in the display (Marantz p/n HQ300580R, FL DISPLAY model VFD29-1403FS VSLVFD291403FS)

If there's no fluoro tube AC voltage appearing on main board JFN701 pins check the connection on the main transformer.

Here's the service manual that will help.

The main pcb schematic is on p.15 (0f 61)

The front pcb is on p.13

The wiring block diagram is on p.7 although I think that there's a mistake as it shows FN710 going to the standby board and not the main transformer. JW104 on the standby board goes to JFN102 on the main pcb JFN102 does not go to the main transformer as shown

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Hi jayeff, and thank you for the reply! I have just measured the voltages as you describe above. At JFN701 I'm getting 4,9v AC; at JFN702: 4,6v AC; and at JFF101: 4,6v AC. Which is clearly higher than what the schematic tells us. Any thoughts?

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@swellenuwe

Were you measuring each pin to earth or across both pins?

There are 2 different 5V supplies for the front panel.

5VL and 5VD on JFF101 6 & 7, are they both there?

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I measured across both pins. I just re-measured each pin to GND and they both measure 2,7v AC. Both 5v supplies, and the 3,3v supply are present at JFF101.

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After a bit more troubleshooting this morning: When the receiver is first powered on, the main power relay clicks 5 times. 1-0-1-0-1. Thereafter it will usually only click once. Front panel remains dead. I then measure at JFN101: Pin10= +4,4v; Pin5(MUTE)= +3,28v; Pin6 (PROT2)= -0,1v; Pin7 (Prot1)= -0,1v. So it seems there is an active fault somewhere. I measure for DC at the speaker outputs, and there is none. I checked all the large power transistors on the amp side, no shorts. Thoughts? Thanks again, and happy Friday!

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@swellenuwe

Does "Thereafter only click once". mean that it stays on?

Does the speaker relay turn on when the unit is first powered on and then turn off and then turn on again when the Power relay stays on?

I would also check that the various 5V supplies are also on each board e.g. 5VA, 5VD (5VL does appear on the front panel board)

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