Marantz 1060 recap fail.....?

[Briant8]

Hi All!
It's been a while since I've worked on any pieces, but here I am elbow deep in a cherry little 1060 amp that I found recently.
She powered up and worked just fine but had that muddy kind of sound that seems to be a popular complaint about them. So I read up on several 1060 recap threads and jumped in.

I've managed to lose the right channel somewhere along the way.
Here are the steps I've taken so far:

Replaced main fuse, DeOxit to all pots, adjusted amp as per the manual, tested all inputs/outputs.

I began the recap and for some reason started with the phono board (P900) and was 1/2-way through it before I realized it, so I just finished it up and tested the unit = all good!

Moved on to the preamp board (P400) recapped and tested = all good!

Recapped the power supply board (P800) and tested = no right channel :-/

I immediately re-Deoxit all pots again and test again = no right channel
I replace all of the original caps back onto P800 and tested = no right channel
(Then put all of the new caps back onto P800)

Backtracked to P400 and replaced all original caps and tested = no right channel
(And then put new caps back onto P400)

(Didn't figure the phono board is in this equation and so have not messed with it's of yet)

Went back to the volume and balance pots and actually removed them one at a time, disassembled them, cleaned them, reassembled them and reinstalled them and tested after each = no right channel.

Swapped wires from volume pot to bottom of preamp board (to test volume pot, it has a right/left output sides despite R/L volume levels not being able to be adjusted independently) = no right channel

Swapped wires from balance pot to volume pot (to test balance) = no right channel

Getting desperate, I actually drilled a very small hole into the backs of all of the other push button control and gave them a DeOxit treatment and then blew them out with canned air = no right channel

Tested preamp out into another amp = no right channel (stopped here as it appears to be the preamp, right?)

Oh, and voltages, let's not forget the voltages! (All tested with ground to chassis)
P800:
J801 = 37.8V AC
J802 = 37.8V AC
J803, 804, 805 = 14mV AC
J806 = 36.4V DC
J807 = 29.2V DC
J808 = 7.22V AC

P400:
J404 = 29.2V DC
J408, 409 = 7.0V DC
J411, 412 = 8.5V DC
J414, 415 = 5.5mV DC
All others 0

So, despite my overwhelming desire to curl into a ball and cry like a baby and then chuck the unit off the balcony, I'm here once again appealing to the Marantz gurus amongst you...



What next?
I'm tapped out of ideas other than the transistors on the preamp board, I guess recapping the power supply board could have toasted them, but why only one side?

Also, I have not touched the main amp board at all.

Thanks in advance!

Brian

 

[willyrover]

I'd say it's more likely a connection broke or a wire pulled off somewhere while moving stuff around during the recap.

 

[tranguru]

801 = 37.8V AC
J802 = 37.8V AC
J803, 804, 805 = 14mV AC
J806 = 36.4V DC
J807 = 29.2V DC
J808 = 7.22V AC

not sure I understand....


J808 should be zero V in DC - why are you using AC?

J807 should be at 27V
806 at 35v DC

difficult to understand why only right ch is out.

check that power xtors are ok - at least h002 and h003

luck
robin

 

[Briant8]

I checked all of them in both AC and DC to see if something funky showed up.
J808 was 0V in DC but showed the 7.22V in AC, didn't know what to make of that and just included that finding.

As for J807 & J806, I just figured that those values were within the margin of error of my DMM. I rarely find any voltages exactly what the schematic says, anyways.

Yeah, I'm stumped!

 

[rBuckner]

I'm with 'willyrover' that it's somewhat likely that a wire got broken off. That or possibly a speaker connection was lost in the jostling around of the unit while working on it. Just to be sure, swap the speaker wires just to verify that a channel is really missing.

If J808 was 0Vdc I bet it wasn't really 7Vac, try again. With power off you can also measure the resistance to ground. It wouldn't be the reason one channel would drop out.

A scope would be best but if you can hook up a steady signal source like an audio signal generator you can measure at various points from good channel to bad in AC volts mode to see where the signal loss is. I've heard of folks using smart phones and sound output from computers as signal sources too.

Where are you located?

 

[tranguru]

I agree actually - issue with ground.

 

[Briant8]

Alas, no scope to use...
I'm in Portland, OR.
I will look again for a loose wire.

(Oh, and J808 still has 7.2V on it and 0V DC. All others tested the same as I listed originally)

So, here's the latest.
Tested amp section with iPod to Aux 1 (uncoupled from preamp), it seems good. Normal sound/volume from both channels.

(So in my mind that leads me back to the preamp, right?)
Recoupled amp/preamp and tested again, noticed that I am actually getting very faint bleed through music from the right channel when balance is turned to left.
It gets slightly louder as balance is turned to the right and then very, very faint again when balance control is full-stop to the right.

And then left channel will get loud very quickly as balance control arely starts to move back towards center.

I completely unsoldered/ resoldered J401, 402 & 403 (this is where the volume pot connects to preamp) and the resoldered J403 ground to chassis.

Now I'm getting white noise sound through Right channel that was not there before.
However, can hear music playing over the white noise sound.
(Music still bleeds through either channel through)

As I'm looking for loose wires, the negative side of the gray double-wire coming from the phono input snaps off of that multi-ground board jumper thing attached to the from of the chassis, so I resoldered that (retested at that point, no change)

Looking further for loose wires, the blue wire between J302 & J406 comes off of J302, so I resoldered that. (No change in sound though...)

So, I'm kinda thinking faulty balance pot here, what do you think? Keep in mind, I've already cleaned it to the point of disassembling it and cleaning it along with the normal Deoxit in the side and top holes.
Or perhaps a faulty volume pot? But again, disassembled and cleaned it as well.

Remaining stumped in Portland,

 

[Denten]

I'm kinda thinking faulty balance pot here, what do you think?

A dead balance control killed both channels on my 2385, I found the problem using an old powered computer speaker that I cut the mini jack off replaced it with probes, followed the signal with that.......worked like a charm!

 

[willyrover]

But it worked correctly before the recap?
I'd be very surprised if the balance pot happened to fail at the exact time you were replacing caps.

 

[Briant8]

That sounds like a genius idea.
I guess I need to dig up a tutorial about how to trace a signal path...
I suppose that and how to actually read a schematic are the next curves on this learning path!

At the moment, I'm trying to recheck my connections to/from the volume and balance pots.
I'm having trouble translating the connections on the schematic of R002 (see pic) to the 8 physical leads on the volume pot.
I mean, I can trace the wires to where they attach elsewhere on the unit, but am unsure wether I mixed one or more of them up when reattaching them, despite labeling and photographing them when I removed the pot

{When I look at the schematic, it appears to me that there are 5 leads on R002 when there are actually 8 on the pot. I've got that the two dots most adjacent to the center dot are the 2 weird leads on "top" of the pot that attach (red & white wires) to the loudness switch; and that the 2 dots outer to those are the blue & yellow wires that go to the balance pot. However, there are 4 more leads on the volume pot, and the main trouble is that I don't know how to discern L/R from the schematic to make sure I don't have any crossed}

Grrrr......

 

[Briant8]

But it worked correctly before the recap?
I'd be very surprised if the balance pot happened to fail at the exact time you were replacing caps.

I know, right!?
I also tested both 250k Ohm pots (as far as resistance) with my DMM and they seemed work just fine.

 

[willyrover]

When soldering in the new caps, is it possible you created a solder bridge somewhere?



Other than that, not sure how to proceed at this point without a way to trace a signal through the preamp.

If you're sure that all the boards (left and right sides) are getting the voltages they need, and that the circuitry is actually active, you need a way to trace a signal.

I recently picked up a scope, but before that, I was able to find a bad solder joint in a Yamaha preamp that was dropping a channel by playing a sine wave (100Hz I think, I used a tone generator app) into both channels with enough amplitude to read an AC voltage on my DMM. Then by comparing voltages on the signal path between the good channel and the bad channel I found where it was dropping out.

I was lucky that problem was between the input and any active circuitry because I'm not sure how this technique would work once you start getting onto the preamp board.

 

[Briant8]

When soldering in the new caps, is it possible you created a solder bridge somewhere?

I thought of that and that's why I cleaned, removed, replaced and resoldered J401-403. And then regrounded P400.
All that got me was the white noise from the right channel that wasn't there before (and a little more volume, I suppose)
The signal bleed through on both channels is what is bugging me. That's usually a dirty switch or pot, right? I will reclean them all again and see what happens.

Thanks for the good ideas, I'll look into tracing the signal path. Are you aware of an easy to understand thread on that topic?

 

[willyrover]

The bleed through into the bad channel could actually be coming from the good channel. (If that makes any sense.) Disconnect the input from the good channel and see if you can still hear anything.

Not sure of any threads about tracing signals. I just got a scope and am starting to figure out how to use it. But generally speaking you input a signal such as a 1kHz sine wave that you can see on the scope. Then, with the schematic, probe the points along the signal path until your don't see the sine wave anymore.

 

[culcuhain]

Are all the caps oriented correctly. I am assuming they are polar specific electrolytic caps.

 

[Briant8]

The bleed through into the bad channel could actually be coming from the good channel. (If that makes any sense.) Disconnect the input from the good channel and see if you can still hear anything.

Not sure of any threads about tracing signals. I just got a scope and am starting to figure out how to use it. But generally speaking you input a signal such as a 1kHz sine wave that you can see on the scope. Then, with the schematic, probe the points along the signal path until your don't see the sine wave anymore.

So, I did deduce that the right channel music is indeed coming from the right channel and not the left by plugging and unplugging the L/R inputs. Volume is still only a fraction of normal, and the white noise static is still present on the right side.
I pulled all caps from preamp board and tested them and then replaced them (they were all normal reading and oriented properly)

I then pulled each matching transistor pairs from the right and left sides one pair at a time. All right side transistors' hfe read lower than the corresponding left side's transistors. Each time I pulled theswapped the stronger reading left transistors onto the right side side of the board, testing function with each pair. This made no difference.

Super bummed now in Portland....
Brian

 

[willyrover]

And you have confirmed the preamp board is "powering up" on both sides?

J404 on the preamp board is fed from J807 on the power supply board. Your original post says that voltage is reaching J404 but then it splits off symmetrically to left and right channels. Can you follow that voltage from J404 through the board and compare good side values with bad side values.?