My 1060 Over heating

Whitebear15

Active Member
Im sure sothebody on here can answer this question. I have 2 Marantz 1060s, both have had the amplfier section recapped by professionals.
I decided to recapp the crossover capps and the mains cap along with the power supply board, both done now, with same make and value capps, both amps sound great now, but I have a problem with the second recapped amp, its running quite hot now, it didnt before the recap, its much hotter than the first amp I did.
Could the bios settings need doing now, and if so, is there any easy way to doing that.

Cheers Rob
 
It's a good idea to check the bias (idle current) setting on both channels on both amplifiers.The service manual describes how to set the bias. You'll need a digital multimeter, ideally with mini grabber tips (not probes).

What is heating up? Is it the output transistors? Which side is heating up first? Or is it the power supply? Let's narrow it down a bit.

1060 power amplifier adjustments.jpg
 
Hi Runningdog, Its the output transistors, mainly the right channel, you can feel the heat coming of the heatsinks.
 
I'd also suspect high idle current. If it's not high while it's just been on a short while, say 15 minutes, keep an eye on it as the heatsink warms up. It may not be tracking well. If you can get it to the desired 7.5mV after it's warm leave it there. When it's cooler it will still probably be doing some current, measured as a few mV.
 
Yep, thats what I meant, coupling caps.
I havent got any crocadile clips for my Volt meter, looked at the circuit and wouldnt like to go poking about with the VM probes.
Did some reading in the forums, sombody said you could take bios reading attaching the VM probes into the speaker outputs.
I set my VM to 20mv dc, the meter reading started counting down, untill it read 0 volts, that happened on both channels, what does that mean?
Amp been on playing for the past 3 hours, even thou the heat sinks are quite warm, it sounds great.
 
Connecting your voltmeter to the speaker outputs will give you the DC offset reading (sometimes called DC bias) which leads to confusion. The 1060 is capacitor coupled so 0 volts DC is a good result.

You need to check / set the Idle Current (also called bias). Number 1 is the procedure for the 1060.

Screen Shot 2017-09-20 at 4.39.21 PM.png

The resistors you need to connect across are along the bottom edge of the amp module so it's best to do this adjustment with the amp on its side. Resistors you're measuring across are outlined in red, connection points for your meter are outlined in green.

Screen Shot 2017-09-20 at 4.43.24 PM.png
 
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Brilliant Willyrover, That diagram explains it all, been hunting around AK for the answers for weeks. Couldnt understand what people where going on about. I can understand it now, just need a couple of crocadile clips to proceed. Many Thanks Rob
 
we call them "alligator clips" over here but grabber probes work even better for stuff like that

like these:

http://www.techni-tool.com/458TE244...hhI7GJhJvfJLBne3-dkhbSU2AxRXy7NxoCDSEQAvD_BwE

if you are a retro grouch like me and have an old Simpson or Triplett meter with the weird shielded bananas that allow you to use the DMM type probes that everyone else uses I did find some adapters for those but the part numbers might take me some searching.
 
As for the symmetrical clipping adjustment, if you dont have a scope adjusting the voltage across the coupling caps to 1/2 of the voltage across the main filter cap using trimmers R723 and R 724 will get you darn close. Its only a real issue when cranking it up close to clipping. I tried this and then used a scope to messure the difference and the difference was minimal.
 
Do I leave the speakers conected while taking a reading on the voltmeter?, sorry to sound so thick, Im new to electronics, even thou I ran my own computer shop for 20years, it was a differant ball game.
 
As for the symmetrical clipping adjustment, if you dont have a scope adjusting the voltage across the coupling caps to 1/2 of the voltage across the main filter cap using trimmers R723 and R 724 will get you darn close. Its only a real issue when cranking it up close to clipping. I tried this and then used a scope to messure the difference and the difference was minimal.
Good to hear that Lavane, was wondering how accurate it was.
 
Do I leave the speakers conected while taking a reading on the voltmeter?, sorry to sound so thick, Im new to electronics, even thou I ran my own computer shop for 20years, it was a differant ball game.


For the bias adjustment, I don't think it matters if speakers are connected or not. Idle current won't change much (or at all).

What does matter though is that you take the measurement with no signal input and volume all the way down.


For the second part (symmetrical clipping adjustment), you'll need to drive the amp into clipping with an 8 ohm dummy load attached. Or just follow Lavane's tip in post #10. No dummy load or scope needed.
 
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hopefully this one sets up good right away .. most cap coupled output amps i have set up really required 2 meters as one setting can affect the other .
Good. Point! Even with two meters there is some back and forth. The first one I recapped, a 1030, took what seemed like forever using one meter. And let it sit turned on, no signal for about 20 minutes to get it good and warmed up first.
 
Good. Point! Even with two meters there is some back and forth. The first one I recapped, a 1030, took what seemed like forever using one meter. And let it sit turned on, no signal for about 20 minutes to get it good and warmed up first.
I have 2 VM meters, going to order new leads for them with crocadile clips. Thanks
 
For the bias adjustment, I don't think it matters if speakers are connected or not. Idle current won't change much (or at all).

What does matter though is that you take the measurement with no signal input and volume all the way down.


For the second part (symmetrical clipping adjustment), you'll need to drive the amp into clipping with an 8 ohm dummy load attached. Or just follow Lavane's tip in post #10. No dummy load or scope needed.

Not meaning to hijack this thread but does a video link exist on how to do the clipping adjustment step by step using a scope/ hooking up a dummy load etc? I have an old scope but don't really know how to use it, but really want to learn and would love to know how to do this without damaging anything. I'm sure there are other rookies like myself wanting to learn the same.

GT.
 

It's showing a Marantz 1030 but same idea. Starting at 43:00 bias adjustment then symmetrical clipping adjustment.

EDIT: Just noticed around the 46:00 mark he says the pot he just adjusted is the "DC offset pot". It's actually the bias (idle current) pot.
 
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I have 2 VM meters, going to order new leads for them with crocadile clips. Thanks
I keep a bundle of jumpers with alligator clips on both ends. Cheap and handy. Just clip one end to your probes and the other to your test points. A tube amp I just built had two bias , driver voltage, B+ and B- test points. Having six meters and clip jumpers made quick work of getting it adjusted.
 
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