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DBT faint but never unlit.

R

ReisDaddy

Active Member
Hello, i have Marantz 1180dc, power it up with DBT.

Before i make a thread in Marantz sub forum but its different story, but maybe i was in the wrong subforum, is it ok to make new thread here? Full story is in here:

https://audiokarma.org/forums/index...ide-restoring-marantz-1180dc-1180-dc.1037127/

So my new problem is..
I use 75w bulb. Start bright 100%, goes dim but after 5-10 seconds starts to light up until it is maybe less than 5% bright even after the relay click.
Here is DBT when all board in complete.

IMG_20230822_080356.jpg

Trying to narrow down, then i detach all board including filter, pre amp, main amp, only relay board and rear panel left. The DBT still lit very faint, maybe less than 5%.
Here is the DBT result that relay board only left on the amp:

IMG_20230915_164040.jpg

This DBT when plugging my 40w solder:

IMG_20230918_093038.jpg

I am new to this vintage amplifier. Is this normal? Or something happened somewhere?
Any idea where to troubleshoot?

Here is the relay schematic.

SM-Relay.jpg

Thank you for any input.
 
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xraytonyb just released a video this morning you might be interested in.

2 things in common with you. its a marantz and the dim bulb does not go completely dim.

he does everything with a dmm, not fancy gear.

just gives you an idea for troubleshooting. it is not necessarily your solution.

 
Perhaps you could find the idle current draw of this unit online? I had a Marantz 1122DC here yesterday that I finished working on. A 65W bulb would stay faintly lit on that thing. I would think the 1180DC would have a fair amount of idle draw. 90 Watts per channel amp? I could see where a 75W bulb might be too small to test an amp that big.
 
ReisDaddy said:
Trying to narrow down, then i detach all board including filter, pre amp, main amp, only relay board and rear panel left. The DBT still lit very faint, maybe less than 5%.
Here is the DBT result that relay board only left on the amp:
Click to expand...
I think something is going wrong here if only the relay board draws more current than a 40 Watt soldering station. You might have too much leakage in one of the main filter capacitors.
 
Thank you guys for all your input.

ecluser said:
I think something is going wrong here if only the relay board draws more current than a 40 Watt soldering station. You might have too much leakage in one of the main filter capacitors.
Click to expand...
I will report back.

Warren-Oates said:
Perhaps you could find the idle current draw of this unit online? I had a Marantz 1122DC here yesterday that I finished working on. A 65W bulb would stay faintly lit on that thing. I would think the 1180DC would have a fair amount of idle draw. 90 Watts per channel amp? I could see where a 75W bulb might be too small to test an amp that big.
Click to expand...
May i see the photo of the DBT result of Marantz 1122dc?

@painttoad Thank you for the video, but its not complete yet.
But almost the end of the video around 1:20:00, he try to power the main amp directly using jumper from big caps. The DBT is totally unlit.
 
Last edited:
@HPMguy i did nothing yet, when i check the DBT again, it is orange filament. At the camera/photo its looks glowing more.

I just check the iddle current the meter set to 20A, result is 0.14 A x 220v = 30w?

IMG_20230919_094513.jpg

Is it normal?
 
I gave it back to the owner yesterday, no longer have it.

30 watts with only the power board? Is that what you are saying?
 
Warren-Oates said:
I gave it back to the owner yesterday, no longer have it.

30 watts with only the power board? Is that what you are saying?
Click to expand...
Yes. Only relay board (PN00) + big caps.

If im not wrong, marantz power board is P8xx right? In marantz 1180dc its power board in the pre amp board in the same board to phono.
So currently exclude power board.
 
I did pull the JN11 and JN12 on relay board, so there is no power goes to relay right?
Result same orange filament.

Im afraid to desolder the cable that in square rectifier, or the leg of big caps.
What is the easiest way to check the big caps? so many cable around it, afraid to ruin them all.
 
Last edited:
I can unscrew and desolder the plate that hold big caps negative pin.

IMG_20230919_124220.jpg

The DBT is still orange filament. While i can check the big caps, i think its still good 19.21mF and 19.62 mF.

So i can move on and live with that orange filament right?
 
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painttoad said:
xraytonyb just released a video this morning you might be interested in.

2 things in common with you. its a marantz and the dim bulb does not go completely dim.

he does everything with a dmm, not fancy gear.

just gives you an idea for troubleshooting. it is not necessarily your solution.

Click to expand...
that guy is working on electronics while wearing a gold ring and a metal watch... I think he is the "Dim Bulb"
 
30 watts with no relay and no main caps? That should translate into some heat somewhere. Transformer get warm? Bridge? I would leave it on for a bit and try to figure out what is getting warm for a clue where the 30 watts is.
 
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