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Marantz PM-KI Pearl Lite repair

JeffS7444

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For what it's worth, my Marantz NR1608 was plagued by intermittent right channel headphone output, and here's some of the thought process I followed:

Did tapping on the chassis make a difference: Usually not
Power on/off: No real difference
Jiggle and unplug/re-plug headphones: No real difference.
Turn up volume higher: Worked, sometimes had to do this repeatedly, and then unit worked fine for remainder of listening session

Clearly there is a lot of relay action going on, as the unit senses when headphone is plugged in and relays are engaged. I disassembled the receiver so I could determine the exact parts being used (Hongfa Technology HF115F 012-2ZS4B). Figuring that some time would pass before the new parts would arrive, I reassembled the receiver, and surprise, the unit worked 100% for a couple of days! I had unplugged the CPU board and a number of interconnects but had otherwise made no changes, so this was "interesting".

On a hunch, I disassembled the receiver once again, but this time I treated the internal (Sn-plated) connections to some contact cleaner before reassembling. Worked great when reassembled, though headphone sensing started to become intermittent. So I squirted a little more contact cleaner into the (Ni-plated) headphone jack. That did the trick! I've experienced no further problems in the months since that time. Why shiny new internal connections in a late model receiver kept in a clean and dry environment should need cleaning, I have no idea.

As for the stock relays, Hongfa Technology is a new name to me, but manufacturer's specifications showed that Marantz had selected sealed units with AgNi contacts, which is exactly the sort of thing that I'd want to see for this application, so I'm glad that I did not waste $$ by replacing perfectly good parts. Your own situation may be different of course, but if no speakers had been connected to your amplifier's "B" terminals, there would have been no current flowing through that suspect relay, hence the contacts should not be pitted or worn. And even if oxidized, Ag is a good electrical conductor.
 
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xaviescacs

xaviescacs

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For what it's worth, my Marantz NR1608 was plagued by intermittent right channel headphone output, and here's some of the thought process I followed:

Did tapping on the chassis make a difference: Usually not
Power on/off: No real difference
Jiggle and unplug/re-plug headphones: No real difference.
Turn up volume higher: Worked, sometimes had to do this repeatedly, and then unit worked fine for remainder of listening session

Clearly there is a lot of relay action going on, as the unit senses when headphone is plugged in and relays are engaged. I disassembled the receiver so I could determine the exact parts being used (Hongfa Technology HF115F 012-2ZS4B). Figuring that some time would pass before the new parts would arrive, I reassembled the receiver, and surprise, the unit worked 100% for a couple of days! I had unplugged the CPU board and a number of interconnects but had otherwise made no changes, so this was "interesting".

On a hunch, I disassembled the receiver once again, but this time I treated the internal (Sn-plated) connections to some contact cleaner before reassembling. Worked great when reassembled, though headphone sensing started to become intermittent. So I squirted a little more contact cleaner into the (Ni-plated) headphone jack. That did the trick! I've experienced no further problems in the months since that time. Why shiny new internal connections in a late model receiver kept in a clean and dry environment should need cleaning, I have no idea.

As for the stock relays, Hongfa Technology is a new name to me, but manufacturer's specifications showed that Marantz had selected sealed units with AgNi contacts, which is exactly the sort of thing that I'd want to see for this application, so I'm glad that I did not waste $$ by replacing perfectly good parts. Your own situation may be different of course, but if no speakers had been connected to your amplifier's "B" terminals, there would have been no current flowing through that suspect relay, hence the contacts should not be pitted or worn. And even if oxidized, Ag is a good electrical conductor.
I don't have the time, the skills and the materials to try to clean the relay contacts, so I prefer to change them.

I've checked everything else as @restorer-john suggested, and it seems the relay of the B channel is the problem. I will replace both though, just in case.

Now that you mention Hongfa, some of the FTR-F4AK024T relays I ordered were actually Hongfa HF24F, way cheaper than the Fujitsu ones, so I'l use the latter.

relays.jpg
 
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xaviescacs

xaviescacs

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Hi folks.

I've replaced the relays. My soldering skills are pretty basic but the final result is quite good. The main issue I had is that sometimes I applied too much pressure and the solder tip sliped and scratched the PCB. At some point I realized the temperature was too law and I needed to be more patient. So the second one, the lower one, went better.

IMG_20220316_153302385.jpg


IMG_20220316_160631837.jpg


Now I have a problem with the missing speaker cable post because the Marantz technical service isn't responding, I asked for the piece 4 months ago and they keep saying they are expecting it.. it takes longer than usual they say...

So I've decided to find an alternative. It won't have "Marantz" written on it but will work.

I wanted to post here to seek for your advice, once more.

I've made some pictures of the post:

IMG_20220321_193054056.jpg

IMG_20220321_193243101.jpg
IMG_20220321_193331689.jpg


Do you think something like this could work? I have no way to be sure the thread pitch is the same. What's your experience on that?

Thanks in advance.
 

restorer-john

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Don't worry about the 'damage' on the PCB. It is 90% cosmetic and only the lacquer. Get some 99.5% isopropyl or methylated spirits and a cotton tip. Clean it up and move on. :)
 
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xaviescacs

xaviescacs

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It is possible that those binding posts have a P of 0.75 mm? The inner screw I mean.

The Marantz ones are named SPKT-1, bit I can't find a data sheet of those with its dimensions.
 
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JayGilb

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index.php


Is this image from a different receiver ? The earlier image had threaded connectors that made contact with the pcb, whereas this one is using insulated washers to keep connectors from contacting the ground plane.
 
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xaviescacs

xaviescacs

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Is this image from a different receiver ? The earlier image had threaded connectors that made contact with the pcb, whereas this one is using insulated washers to keep connectors from contacting the ground plane.
It's the same, but in this picture the PCB with the relays and the whole power amplifier stage have been removed. The posts have two nuts: one more thick, the one in the picture, that tightens them to the chassis, and a thinner one that makes the electrical contact with the PCB.
 
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xaviescacs

xaviescacs

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Job done!

IMG_20220404_134511647.jpg

Almost identical, isn't it?

After replacing both relays both channels work flawlessly at any volume, so problem solved.

Thanks to everybody but specially to @restorer-john, who pointed me towards the right direction. :)

With the excuse of repairing this and another gadget, and thanks to people's advice here and there, I've built a decent soldering kit. Who knows what's coming next...
 
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restorer-john

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Job done!

View attachment 197575
Almost identical, isn't it?

After replacing both relays both channels works flawlessly at any volume, so problem solved.

Thanks to everybody but specially to @restorer-john, who pointed me towards the right direction. :)

With the excuse of repairing this and another gadget, and thanks to people's advice here and there, I've built a decent soldering kit. Who knows what's coming next...

Awseome! Can I say I'm proud of you! :)
 
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Thanks for posting this.

I had the same issue with my speakers A relay on my Pearl Lite, either no sound or very distorted right channel. I didn't have the equipment to swap the relays over. Speaker B relay was ok so have been using that in the mean time.

I took it in and $150NZD later the amp has been serviced and both A and B relays have been replaced with higher spec OEG OSH-SH-224DM3 relays.

It's working great now.

 
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