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Leestereo's Marantz 1090 Restoration/Upgrade

bktheking said:
I spent a good few hours listening to this integrated. I find the newer marantz stuff sterile, lifeless and almost lacking in the marantz vintage sound. This unit was all but that. I listened to the 1090 connected to my Quartets. Klipsch speakers are very revealing if you didn't already know. Ben was the pioneer at the 1060 BOM, those people that have followed that BOM know what a 1060 is and what it sounds like after Ben's list is applied- it's nothing short of breath taking. The 1090 is just that- crisp , clean and anything but fatiguing to listen to. I had a 1090, it didn't sound anything what Ben has produced with this unit- awesome work brother.
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That's kind of how I felt about my 3200 after I was done with it. Its pretty bright. I like it, but I can listen to my 33 or 1030 all day long but after about 1/2 hour I have to turn the 3200 off. Maybe it can use a ceramic cap upgrade.
 
I'll second the comments about Ben's perceptiveness relative to truly improving the sound. It goes deeper than "what's the most expensive cap I can stick in" - he really understands the functioning of the circuit and how to make significant changes. I found the improvement to the 1090 to be very stiking.
 
Sorry to resurrect this thread after so long, but I've had a torn up 1090 sitting on my bench for months. Is there any chance of getting a parts list for the replacement/upgrades that Leestereo used?

Jack
 
In the process of doing the "Lee" mod. I notice that c423 isn't listed in the original manual. After pulling the cap I noticed the original is 47uF not 10uF as listed in the Lee mod. The modification calls for a 33uF/50v. Is this correct?
 
The C423 capacitor is in the schematic, it shunts the zener Q410, the replacement was a 100µF/50V low ESR type. I also corrected the text in post#7; thanks for catching this mistake in the thread, fast400.
 
I'm trying to put together a Mouser order to refurbish my 1090 following Leestereo's recipe. The Panasonic stacked film caps are apparently going extinct. Will these: http://www.mouser.com/ProductDetail/EPCOS-TDK/B32529C1474K189 work instead? They have 5mm lead spacing, and they are the "cut tape" version, which I'm hoping will have leads that are long enough to work with. Or can someone suggest another alternative? Need .47uF and 1.0uF, 50 or more volts.
 
drew_t said:
...The Panasonic stacked film caps are apparently going extinct. Will these: http://www.mouser.com/ProductDetail/EPCOS-TDK/B32529C1474K189 work instead? They have 5mm lead spacing, and they are the "cut tape" version, which I'm hoping will have leads that are long enough to work with. Or can someone suggest another alternative? Need .47uF and 1.0uF, 50 or more volts.
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The TDK stacked film capacitors will substitute fine; you can also use the Wima MKS2 types or the Kemet R82 types (these are also available from Mouser). Links to the "cut tape" versions for WIMA: http://audiokarma.org/forums/index....anasonic-film-capacitors.703698/#post-9438638
 
@Leestereo so a question, cause I’m currently considering having this done to a 1090 that I’m acquiring.

In your professional opinion, if you compare this to a marantz 22xx (45/70/??), is the 1090 a better “building block” to start from to get a GREAT outcome out of a vintage piece? Or am I better off investing in a different model? I realize this is fairly subjective, but just wondering what your thoughts might be considering your tech knowledge and inside viewpoint on all these units.

Much thanks!
Eric
 
EricMN said:
...In your professional opinion, if you compare this to a marantz 22xx (45/70/??), is the 1090 a better “building block” to start from to get a GREAT outcome out of a vintage piece? Or am I better off investing in a different model? I realize this is fairly subjective, but just wondering what your thoughts might be considering your tech knowledge and inside viewpoint on all these units...
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It depends on the type of sound that one is looking for. The early-to-mid 70s 22xx receivers have a "warm" sonic signature, whereas the later 22xx receivers (and integrated amps) have a more "neutral/clean" sonic signature. Also consider the components that will be paired with the receiver/amplifier: there are many examples of some pairings that work better than others, i.e., synergistic couplings.
 
Leestereo said:
Main Power Amp Restoration/Upgrade


Signal Path Capacitors:

The stock capacitors in the input high-pass filter (C701, C702) were 2.2µF low leakage electrolytic capacitors and these were replaced with 1.0µF Panasonic stacked polyester film capacitors. The F3 of this high-pass filter is 3.1Hz.

The stock capacitors in the low-pass filter (C705, C706) were ordinary 100pF ceramic capacitors. These were replaced with Wima FKP2 polypropylene capacitors of the same value. The F3 of the low-pass filter is 1.6MHz.

The stock C733, C734 capacitors, which determine the low end cut-off of the negative feedback loop, were garden-variety 100µF/16V, 85°C polar electrolytics. These were replaced with 100µF/16V Nichicon MUSE ES bi-polar

The stock phase compensation capacitors (C740 and C741) in the negative feedback loop were ordinary 20pF ceramic capacitors. These were replaced with C0G/NPO capacitors of the same value.


Non-signal Path Capacitors

The capacitor (C704) which shunts the input differential stage zener, was a 10µF/35V electrolytic and was replaced with a 33µF/50V Panasonic FM 105°C low ESR type.

The local decoupling capacitors (C735, C736) were 10µF/50V electrolytics and were replaced with 47µF/50V United Chemicon LXZ low ESR types.

The filtering capacitors for the protection circuit (C711 and C712), were 100µF/35V electrolytics and these were replaced with 120µF/50V Nichicon PW low ESR types.

The capacitors C723, C724, C725 and C726 which shunt the output sampling diodes in the protection circuit were 10µF low leakage electrolytics and these were replaced with 10µF/35V Silmic II audio grade capacitors (somewhat overkill here, but these were the only "low leakage" 10µF caps I had on hand).


Other Upgrades

The open frame trimmer resistors (R771 and R772) used for setting the bias current were replaced with 500ohm mutlti-turn types. The idle current was increased to 25mA from 13mA (the heat sink is still very cool to the touch at the higher setting).

The capacitors in the preamp muting circuit, CV03, CV04 and CV05 were replaced with same value capacitors. Note that CV04 was a 330µF/10V capacitor rather than a 220µF/10V as indicated on the schematic; similarly, CV05 was a 47µF/63V capacitor rather than a 47µF/6.3V as indicated on the schematic.

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Good morning. Sorry for asking on an old topic. Can you tell me the original value of the two trimmers (R771 e R772)? I'm working on a 1090, only the right channel works, the left channel has no sound. No regulation of idle currents. I can't understand the problem. Do you have a tip for me? Thank you
 
Massimogdf said:
Good morning. Sorry for asking on an old topic. Can you tell me the original value of the two trimmers (R771 e R772)? I'm working on a 1090, only the right channel works, the left channel has no sound. No regulation of idle currents. I can't understand the problem. Do you have a tip for me? Thank you
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According to the service manual, R771/R772 are 1k trimmers. It's not called out on the schematic, but is in the parts list in the SM. It looks like @Leestereo used a 500 ohm trimmer as a replacement.

So no sound on the left channel: where to start... I would recommend you start your own thread in the Marantz forum and ask for help. What do you mean by "no regulation of idle currents" on the left channel? What measurement do you see for the idle current? Are you saying you can't get it to stabilize? What is the DC offset measurement on the outputs? Are the output transistors blown, do they test good? Carefully measure voltages on the output transistors, and measure the good channel for comparison.

See what I mean? Troubleshooting can go down a lot of roads. Best to start a new thread for yourself.
 
Thanks for your time, I will purchase the 1K trimmers. I can't record idle currents on the left channel, no readings. By rotating the trimmer the measurement remains 0. While the right channel is playing I can feel the heat of the power transistors, only on the right side. On the left there is no sound and no heat on the power transistors. It seems that something is not making the left channel work. But everything seems correct. Thanks for your reply, you were very kind.
 
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