Marantz 1060B Rebuild & Troubleshooting

[MBuras]

Almost since the beginning of my time on this forum I've heard derogatory comments about the 1060B amplifier. Build quality is terrible, sound is terrible, nothing like the original 1060, etc. So of course I had to find out for myself.

This one came to me in great cosmetic shape and relatively clean compared to most pieces its age.


The problem as noted by the previous owner is that when hooked up to speakers and turned on there was just a loud hum. I confirmed the loud hum regardless of volume being all the way off. And here's where my learning experience comes into play.

I automatically assumed it was a bad filter capacitor. I pulled them and they both measured high on ESR, one much higher than the other. This fed into my reasoning and so I ordered parts cuz I was going to rebuild anyway.

After getting my parts order and rebuilding the power section I was completely mystified when the hum continued. Then followed days of crazy ideas like checking ground connections, checking the rectifier diodes, checking the power switch snubber, etc. No joy.

And then the most brilliant idea ever....check the manual. Duh! And sure enough there is a section on troubleshooting hum.


Point number 3 addresses the issue. I had already replaced the filter capacitors (C808, C809) and the other two power supply capacitors mentioned. That left Q801. Hmmm...hadn't checked that before. Compared voltages to the schematic and something definitely off. Pulled Q801 and put it on my little Ebay tester. Confirmed bad. Decided to check the other 4 power section transistors while I was in there. Also found Q802, Q812 and Q813 were bad. Yikes!

Fired up after power section transistor replacement (after DBT), heard a brief buzz and then silence. Alright, I don't like the buzz but silence after is good, right? Nope. Although all is quiet it's also not playing any music I'm feeding it through Aux.

I noticed on the schematic that Q801 also connects to the preamp board so start checking voltages on QE05 and QE06. One side is fine, the other not so much. Pull them both and test bad. Pulled all preamp transistors while in there and found QE03 and QE04 were bad as well. Replaced all, restested with DBT and sure enough there was music. Yay!!

Goes to show that assuming something is a problem isn't the right way to go. Checking the basics is always a good move. And learning how to at least follow connections/voltages on a schematic (even if you don't completely understand the purpose of the circuit design) is super helpful. I'll put this experience in my toolbox for reference in the future. More learning is good!

Finished pics to follow...

 

[MBuras]

The construction of this amplifier is much like the other late 1970's B models with a single board handling power, preamp, power amp, etc and then some accessory boards. All capacitors (electro, film and ceramic) were replaced with top quality modern components hoping to bring out the best in this design. Almost all uf/pf values were kept the same as original with some minor variations. Again, I wasn't trying to change the design, just realize its potential.

Filter capacitors were upped a little because none of us can resist that, right?


Here you can see lots of the blue Kemet polypropylene films used and well as UPW Nichicons. I still might replaced the trimmers but got them to adjust ok so maybe not.



The phono (foreground) and preamp (behind) were treated to lots of polyester and polypropylene, especially those big Panasonics at the input filter locations of the preamp.



The loudness switch/board is tiny and only has 2 ceramics and 2 films I replaced.



And then the tone control board got the same treatment.

I'm not the final word on anything so take this final assessment with a grain of salt. YMMV.

Overall I think this is a wonderful sounding little amplifier. It has a crazy wide soundstage with a fast, accurate sound without being fatiguing. Not as enjoyable as my benchmark Sansui AU-717 (sorry Marantz fans) but great value for the money. It does lack a few features, the most annoying to me is no way to defeat the tone controls. Also, the volume control has predefinied (detented?) increases which can leave the music either too loud or too quiet with no way to find the sweet spot.

This was a fun project and honestly pretty cheap even with all the film splurges. I bet many naysayers would like this amp a little better if they heard it while blindfolded.

 

[wlhd1610]

Nice work and great write up with pics!

Bob

 

[Steven Tate]

Great work, Mike. That thing is beautiful inside once you did your magic. I’ll bet it sounds great.

 

[MBuras]

Forgot to mention there are no major issues and only 2 minor discrepancies with the parts list in the SM.

CE03/CE04 is a ceramic capacitor that is listed as 68pf but in reality was 220pf.

CF07/CF08 on the tone board are polar electrolytics that didn’t appear to have polarity markings on the board. CF07 should be negative towards the right slider. And CF08 should be negative towards the middle of the board.

And for anyone wondering the filter capacitors are 35mm diameter and 10mm lead spacing on a snap in cap will work just fine. No modifications needed.

Thanks for all the support!

 

[catrafter]

Great work! I enjoy your pictures and write ups, too!

Keep up the good work.

 

[Chicago1985]

The construction of this amplifier is much like the other late 1970's B models with a single board handling power, preamp, power amp, etc and then some accessory boards. All capacitors (electro, film and ceramic) were replaced with top quality modern components hoping to bring out the best in this design. Almost all uf/pf values were kept the same as original with some minor variations. Again, I wasn't trying to change the design, just realize its potential.

Filter capacitors were upped a little because none of us can resist that, right?
View attachment 1220984

Here you can see lots of the blue Kemet polypropylene films used and well as UPW Nichicons. I still might replaced the trimmers but got them to adjust ok so maybe not.

View attachment 1220987

The phono (foreground) and preamp (behind) were treated to lots of polyester and polypropylene, especially those big Panasonics at the input filter locations of the preamp.

View attachment 1220990

The loudness switch/board is tiny and only has 2 ceramics and 2 films I replaced.

View attachment 1220991

And then the tone control board got the same treatment.

I'm not the final word on anything so take this final assessment with a grain of salt. YMMV.

Overall I think this is a wonderful sounding little amplifier. It has a crazy wide soundstage with a fast, accurate sound without being fatiguing. Not as enjoyable as my benchmark Sansui AU-717 (sorry Marantz fans) but great value for the money. It does lack a few features, the most annoying to me is no way to defeat the tone controls. Also, the volume control has predefinied (detented?) increases which can leave the music either too loud or too quiet with no way to find the sweet spot.

This was a fun project and honestly pretty cheap even with all the film splurges. I bet many naysayers would like this amp a little better if they heard it while blindfolded.

Nice work, Do you have the list of caps you changed, the new values, and where u get these from.
Thanks

 

[MBuras]

Don’t have a list but most everything is kept at stock values. Usually source from Mouser or Digikey depending on who has stock of what I want.

 

[Lavane]

And if you order, make a list from what's in the amplifier, not from the schematic or parts list in the service manual. Changes were made during production and weren't often updated in service bulletins or manuals.

 

[goldswimmerb]

The construction of this amplifier is much like the other late 1970's B models with a single board handling power, preamp, power amp, etc and then some accessory boards. All capacitors (electro, film and ceramic) were replaced with top quality modern components hoping to bring out the best in this design. Almost all uf/pf values were kept the same as original with some minor variations. Again, I wasn't trying to change the design, just realize its potential.

Filter capacitors were upped a little because none of us can resist that, right?
View attachment 1220984

Here you can see lots of the blue Kemet polypropylene films used and well as UPW Nichicons. I still might replaced the trimmers but got them to adjust ok so maybe not.

View attachment 1220987

The phono (foreground) and preamp (behind) were treated to lots of polyester and polypropylene, especially those big Panasonics at the input filter locations of the preamp.

View attachment 1220990

The loudness switch/board is tiny and only has 2 ceramics and 2 films I replaced.

View attachment 1220991

And then the tone control board got the same treatment.

I'm not the final word on anything so take this final assessment with a grain of salt. YMMV.

Overall I think this is a wonderful sounding little amplifier. It has a crazy wide soundstage with a fast, accurate sound without being fatiguing. Not as enjoyable as my benchmark Sansui AU-717 (sorry Marantz fans) but great value for the money. It does lack a few features, the most annoying to me is no way to defeat the tone controls. Also, the volume control has predefinied (detented?) increases which can leave the music either too loud or too quiet with no way to find the sweet spot.

This was a fun project and honestly pretty cheap even with all the film splurges. I bet many naysayers would like this amp a little better if they heard it while blindfolded.

I just finished up repairing two of these guys, the build quality is kind of miserable but they sound great. I wasn't a fan, that at least, in mine, all the Transistors were 2SC1400 (failure prone) or 2SA750 (also can be problematic). I also noticed that my larger TO-92L transistors had actually started to "black leg" at the base of the transistor.

Once all that was sorted I was very pleasantly surprised by how nice these guys sound. Sure it's not the OG 1060 but they have an extremely pleasant tone to them.

One odd thing I noticed and can't seem to figure out is that one unit will give an audible buzz when first turned on, only if it's been sitting a bit. The other unit seems to just give a light pop. There's no protection circuit so I guess the buzz is just from my filters charging and amp stabilizing but it's strange to me that two identical units would behave differently. I didn't swap the main filters but they both showed good on my cap tester.

 

[Lavane]

I just finished up repairing two of these guys, the build quality is kind of miserable but they sound great. I wasn't a fan, that at least, in mine, all the Transistors were 2SC1400 (failure prone) or 2SA750 (also can be problematic). I also noticed that my larger TO-92L transistors had actually started to "black leg" at the base of the transistor.

Once all that was sorted I was very pleasantly surprised by how nice these guys sound. Sure it's not the OG 1060 but they have an extremely pleasant tone to them.

One odd thing I noticed and can't seem to figure out is that one unit will give an audible buzz when first turned on, only if it's been sitting a bit. The other unit seems to just give a light pop. There's no protection circuit so I guess the buzz is just from my filters charging and amp stabilizing but it's strange to me that two identical units would behave differently. I didn't swap the main filters but they both showed good on my cap tester.

With the cover off, see if it's coming from the power transformer. If it is, and has endbells covering the windings sometimes putting some folded cardboard inside the bell that puts some pressure on the winding can kill mechanical noise.
I've done that along with using rubber washers on the transformer mounting tabs between the tabs and chassis, both sides of the chassis.
Out of all the 70's Marantz gear I restored I steered clear of the 1060B and the 1090 just because of the construction. The 1060 does look nice though. If they had kept the midrange control, I might have gave on a try.

 

[goldswimmerb]

With the cover off, see if it's coming from the power transformer. If it is, and has endbells covering the windings sometimes putting some folded cardboard inside the bell that puts some pressure on the winding can kill mechanical noise.
I've done that along with using rubber washers on the transformer mounting tabs between the tabs and chassis, both sides of the chassis.
Out of all the 70's Marantz gear I restored I steered clear of the 1060B and the 1090 just because of the construction. The 1060 does look nice though. If they had kept the midrange control, I might have gave on a try.

The buzz is through the speakers and not mechanical, and it only happens if the main filters have fully discharged, right on power on it'll buzz. I just find it strange that one buzzes when the amps warm up and the other doesn't even when everything I've done to each is the exact same.

 

[Steven Tate]

You might see if you can measure AC mV at the main filters during startup and after the hum goes away. There should be less than 100mV or so. I wonder if AC is leaking through during charge up, but settling down when it gets charged. If so, you might need to replace that cap. If you get significant AC, you might even compare to what happens on the unit without hum.