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Restoration worklog: Marantz Esotec PM-4

bonsaichop

bonsaichop

Member
Restoration worklog: Marantz Esotec PM-4 (15WPC Class A) Finshed!

*update* If you havn't heard of this amp before it's worth checking out. 60wpc class A+B or hit the magic button and it does 15wpc of Class A :)

Here's some info if you havn't seen one before;

http://audio-database.com/MARANTZ/amp/pm-4-e.html
http://www.thevintageknob.org/marantz-Pm-4.html

Hey all,

Well while my 2220B is off the bench awaiting for parts and having it's components run in I thought i'd start on my next project A Marantz Esotec PM-4. I paid a little more than I should have in it's condition but it was supposedly working. When I plugged it up, it had a bad left channel, a quick clean of the pots didn't help, and then it lost sound in both channels! Upon further inspection it looks like 6 caps have already leaked out, and even started corroding surrounding components! Nothing that can't be fixed however so here it is. The PM-4 restoration work log!

First off, here's some outside pictures of the unit, very nicely built, as much as I love the external heatsinks on the sides, it makes for a pain in the ass when handing the unit, everything you hold onto digs right into your fingers!

This unit actually doesn't have the Esotec branding, from what i've read apparently this would be one of the later units, after Phillips lost the naming rights to Esotec and had to rebadge everything sans the Esotec name. Which might make this unit a bit rarer than most? Or less? Who knows?


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Uploaded with ImageShack.us

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Uploaded with ImageShack.us

Uploaded with ImageShack.us

Anyway that'll be enough to wet the appetite for the moment, I'll add more a bit later on today.
 
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Cool looking unit. I'm sure it will sound incredible once you get it up and running. :)

Looking forward to updates on this.
 
Ruxman said:
Cool looking unit. I'm sure it will sound incredible once you get it up and running. :)

Looking forward to updates on this.
Click to expand...

Thanks :) I can't wait to get it up and running myself!

Continuing on from the first post, the disassembly is a bit strange, the faceplate and the top cover come off at the same time, all the knobs have to be removed, and all the screws around the side for the front panel and the top panel have to be removed. after this the top comes off in a lift and pull action aswell as the front plate. The word of caution is that when you remove the front plate, you essentially remove the screws holding down the front bar behind the plate which has the tone board and switch selector board/phono preamp it's all a bit of a juggle. Boy was it dusty inside! just a real nice thick layer of dust. It also looks like someone has cleaned the front plate with something that has removed the gold/champagne colour as the back of the plate was the color I expected it to be, but the front plate is a bit more silver like the 1xxx series amps.


http://www.flickr.com/photos/66195499@N07/6028281976/ by Bonsaichop, on Flickr

http://www.flickr.com/photos/66195499@N07/6028282392/ by Bonsaichop, on Flickr

http://www.flickr.com/photos/66195499@N07/6027730823/ by Bonsaichop, on Flickr

http://www.flickr.com/photos/66195499@N07/6028283146/ by Bonsaichop, on Flickr

http://www.flickr.com/photos/66195499@N07/6028283548/ by Bonsaichop, on Flickr

http://www.flickr.com/photos/66195499@N07/6027731985/ by Bonsaichop, on Flickr

http://www.flickr.com/photos/66195499@N07/6028284758/ by Bonsaichop, on Flickr

http://www.flickr.com/photos/66195499@N07/6027733173/ by Bonsaichop, on Flickr

And then I found the issue, leaky caps! I'm not sure if they were leaking or if it's the glue but the residue was already starting to corrode the heatsinks and resistors in the vacinity.


http://www.flickr.com/photos/66195499@N07/6028288058/ by Bonsaichop, on Flickr

http://www.flickr.com/photos/66195499@N07/6028287698/ by Bonsaichop, on Flickr

(continued next post)
 
(continued)

Now to get alot of the caps out, it wasn't as easy as going from underneath. The unit's structure is made of 4 cross beams connected to the heatsinks which make the sides with a front, rear, top and bottom cover. Not fun! I had to work one side, removing the side heatsink, removing the existing caps, put the heatsink back on to give it structural integrity, then clean the boards using orange cleaner and IPA to remove the glue and dust then take the heatsink back off to solder the new components in place...

Then for the other side, lather.. rinse.. repeat.


http://www.flickr.com/photos/66195499@N07/6028627545/ by Bonsaichop, on Flickr

http://www.flickr.com/photos/66195499@N07/6029183216/ by Bonsaichop, on Flickr

http://www.flickr.com/photos/66195499@N07/6028626519/ by Bonsaichop, on Flickr

http://www.flickr.com/photos/66195499@N07/6028627069/ by Bonsaichop, on Flickr

Soaking the board before removing the goo.


http://www.flickr.com/photos/66195499@N07/6029182626/ by Bonsaichop, on Flickr

Cleaned boards, very embarrassingly I had to get pretty rough to get the goo off. The boards got a little scratched, but once the new caps are in you won't see any of the marks anyway.

http://www.flickr.com/photos/66195499@N07/6029181534/ by Bonsaichop, on Flickr


New Panasonic TS-HA 10,000uF 63v caps. An upgrade from the existing 6,800uF 35v. I also added 1uF 250v film caps as bypass caps underneath each of the 10,000uF filter caps.


http://www.flickr.com/photos/66195499@N07/6028636255/ by Bonsaichop, on Flickr


The old caps were pretty nasty, the stuff that came off was equally as nasty...


http://www.flickr.com/photos/66195499@N07/6029187468/ by Bonsaichop, on Flickr

http://www.flickr.com/photos/66195499@N07/6029184188/ by Bonsaichop, on Flickr

http://www.flickr.com/photos/66195499@N07/6029185100/ by Bonsaichop, on Flickr

And finally a nice clean board! All new Panasonic caps. I also (but regrettably didn't photograph) took the relays off and gave them a good clean, they weren't making perfect contact when I tested them with the DMM.


Untitled by Bonsaichop, on Flickr

For anyone that's curious how I don't get all the screws and whatnot mixed up, I found a novel way of organsing everything every time. I found these 'bead boxes' meant for market stalls that have a glass cover. Using an overhead pen (cleans off with alcohol) I just start writing on the glass. Once the job is done I can give it a quick clean ready for the next job. I have a few of these so If I'm working on several projects I'm not mixing everything up.


http://www.flickr.com/photos/66195499@N07/6029182016/ by Bonsaichop, on Flickr

I had to order in some caps for the tone board and switch/phono board so once they're in i'll get working on that and post some more pictures.

Anyway hope you enjoy to whoever is having a look :)
 
I've never seen that amp before. Looks to be a nice integrated, I like the layout. Good work on the restoration, that glue is a pain to clean up.

I'm gonna have to find some of those bead boxes. That's the best idea for organizing parts I've seen.
 
Jailtime said:
I've never seen that amp before. Looks to be a nice integrated, I like the layout. Good work on the restoration, that glue is a pain to clean up.

I'm gonna have to find some of those bead boxes. That's the best idea for organizing parts I've seen.
Click to expand...

Yeah those bead boxes are fantastic, and reusable!

The amp itself is from 1980 and does 60wpc Class A+B or hit the magic button and it does 15wpc Class A :)

A good bit of info can be found about the amp below;
http://audio-database.com/MARANTZ/amp/pm-4-e.html
http://www.thevintageknob.org/marantz-Pm-4.html
 
Leicalover said:
Great work! I enjoy reading your posts. Thank you! :thmbsp:

Jan.
Click to expand...

Thanks! I enjoy writing them up knowing that people do enjoy reading them. Although I do get a little long winded at times :)

aidynphoenix said:
what kind of orange cleaner did you use on the boards?
Click to expand...

I use "De-Solv-It" (http://www.rcr.com.au/index.php/De-Solv-it/De-Solv-it.html. Pretty good stuff when it comes to removing stickers and the such. And it's pretty benine to most surfaces, the only thing it says that you shouldn't use it on is suede, silk and leather. Best used with a small spray pump bottle.

Update time! The ordered caps came in on Friday but I didn't have a chance to work on it until today. Replaced all the caps in the tone/preamp board. Also replaced the NP electrolytic caps in the speaker switch selection board with film caps (0.22 and 0.47 uf respectively). From my understanding and please correct me if i'm wrong but it's generally considered not good to have electrolytic caps in the audio line so to speak and these should be replaced with their film counterpart.

So that's all the boards recapped no more fiddly soldering woohoo!


http://www.flickr.com/photos/66195499@N07/6040317171/ by Bonsaichop, on Flickr

So I started testing the voltage across the speaker terminals and one was at 357mV! and the other was at 0.1mV.. A much better value. I'm just hoping that it wasn't always set at 357mV and I just accidentally bumped it while working on the unit. Somehow I don't think that this was the case.

Plugged it up to my crappy test speakers for the test run (some pretty hard driven Wharfedale Delta 30's).. the sound wasn't bad, but wasn't that great either. Thinking that this is because of the crappy speaker effect, I tried them on my office setup (Cambridge S30 + Yamaha NS-100M) and still.. not bad not that great. This can't be! My blessed Class A amp sounding pretty ordinary?! As a last resort I tried them on my Mission 710's.. still the same unsatisfying sound. It almost sounds muffled on all the ranges. In Class A and Class AB. Even my partner who I use for my "untrained ear" test said that she though it was pretty average after listening to my restored 2220B and restored 2275 for the past few days while i've been working on them... I'm not sure what's going on here but listening to this amp almost feels like a chore. I've got a pair of Marantz HD 880's coming in a couple of days so i'll give them a go on those bad boys and see if anything happens.

...Unsatisfied :(

I'll have a look in the next couple of days at possibly replacing the input diffs to see if that will have any effect. I tried taking out the bypass caps to see if that was the culprit but i still sounded the same, if not worse. The only other thing I can think of is that the upgrade to the 10,000uf caps may have done something, but I highly doubt it. Unfortunately I have not reference point to compare them to as the amp was barely functioning when I first received it.

Moving on..


So to change focus on the sound quality I polished up the faceplate and all the knobs and button caps. Boy were they filthy! I've taken akin to using diluted simple green to start off the cleaning process with the aluminum parts that have any aluminum rust (the white rust i'm sure we're all aware of). Then I use a magic eraser with my own detergent/deionised water mix and finish off the process using some aluminum polish or just buffing it clean.

Below are some more cleaned up photos of the faceplate, plus a couple of glamor shots with the cover off. Rainy weather today so I was unable to get to work cleaning up the top grill. But I'll keep this post updated once I have done it.

Enjoy the photos!


http://www.flickr.com/photos/66195499@N07/6040316167/ by Bonsaichop, on Flickr

http://www.flickr.com/photos/66195499@N07/6040316483/ by Bonsaichop, on Flickr

http://www.flickr.com/photos/66195499@N07/6041448640/ by Bonsaichop, on Flickr

http://www.flickr.com/photos/66195499@N07/6040898321/ by Bonsaichop, on Flickr

http://www.flickr.com/photos/66195499@N07/6041449004/ by Bonsaichop, on Flickr

http://www.flickr.com/photos/66195499@N07/6040897465/ by Bonsaichop, on Flickr

http://www.flickr.com/photos/66195499@N07/6041448216/ by Bonsaichop, on Flickr

http://www.flickr.com/photos/66195499@N07/6040897853/ by Bonsaichop, on Flickr

http://www.flickr.com/photos/66195499@N07/6041446716/ by Bonsaichop, on Flickr
(A bit overexposed sorry!)

http://www.flickr.com/photos/66195499@N07/6040896747/ by Bonsaichop, on Flickr
 
Did you use the amp even though the dc offset at one speaker terminal was over 350 mV? That isn't even supposed to work. Normally an amp wouldn't come out of protection with that kind of dc offset.

And if it works, it won't sound good.
 
Ruxman said:
Did you use the amp even though the dc offset at one speaker terminal was over 350 mV? That isn't even supposed to work. Normally an amp wouldn't come out of protection with that kind of dc offset.

And if it works, it won't sound good.
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No no! I should have mentioned that. I did bring it back down the best I could, it was sitting between .-5 - 1.5mV.

I was surprised aswell that the protection circuit didn't kick in. I even changed DMM's to make sure that there was nothing wrong with my test equipment. But it was def. reading ~350mV.
 
im loving this photography .
which camera is it that you are using .
the light effects are almost studio grade
plz tell about this photography
im thoroughly enjoying this thread.
i have a pm-6 , id love to make fotos like that of my amp too:tears:
 
Love to follow your threads, nice work and great photos. See pic below this has worked well for me on the glue, and no scratches. Mini plastic spatula, and wood tool.


 
quadklipsh said:
im loving this photography .
which camera is it that you are using .
the light effects are almost studio grade
plz tell about this photography
im thoroughly enjoying this thread.
i have a pm-6 , id love to make fotos like that of my amp too:tears:
Click to expand...

I'm using a Canon 7D SLR with a Canon 24-105mm F/4L lens. When working on reflective surfaces I also use a Canon CP-L II polarising filter to reduce the amount of reflections.

For the flash I'm using a Canon 480EX-II. The great thing with the 7D is that it has remote trigger for the flash so the flash does not need to be connected to the camera and can be set to go off wirelessly. The flash is set on 2 2/3 brightness and I keep it pretty high and pointed towards the ceiling so that the light 'bounces' down giving that natural studio look.

Most of the 'work in progress shots' are done with the flash connected to the camera, also pointing upwards.

The type of camera you use and the lens aren't such a big thing, it's what you do with the flash and how you direct your light which is the big difference.

I'm no professional photographer by any stretch of the imagination, I just like taking pictures and most of them turn out pretty awful anyway!

With a somewhat sense of irony the photo below of my camera kit was not taken with my camera but with my partner's little IXUS 105. Took me longer to take a photo with this point and shooter than it did with my SLR. I kept trying to look into a viewfinder that it doesn't have!


http://www.flickr.com/photos/66195499@N07/6043320523/ by Bonsaichop, on Flickr

patfont said:
Love to follow your threads, nice work and great photos. See pic below this has worked well for me on the glue, and no scratches. Mini plastic spatula, and wood tool.


Click to expand...

Thanks! Well i'll keep posting up new threads on the work I do as long as people enjoy them!

I never thought of using a wood tool, I do use the following though (http://us.element14.com/menda/35621/probe-nylon-spudger-5-5/dp/88H3027) got a few hundred of them from a friend a long time back, they're nylon sticks that are also ESD safe. Fantastic for an infinite number of uses. Although the glue on this unit was some kind of mutant strength glue as I could only really get it off by using a flat blade.

It's a sunny day today so I'll probably get started on the cover and report back later today.
 
Well it got to dusk before I could start work but it didn't take long either. With the trusty wirebrush angle grinder and about 10 minutes of light 'brushing' the old paint and rust was off!


http://www.flickr.com/photos/66195499@N07/6044667425/ by Bonsaichop, on Flickr

http://www.flickr.com/photos/66195499@N07/6044667735/ by Bonsaichop, on Flickr

http://www.flickr.com/photos/66195499@N07/6044668231/ by Bonsaichop, on Flickr

http://www.flickr.com/photos/66195499@N07/6045218068/ by Bonsaichop, on Flickr

http://www.flickr.com/photos/66195499@N07/6044668831/ by Bonsaichop, on Flickr

http://www.flickr.com/photos/66195499@N07/6045216602/ by Bonsaichop, on Flickr

I gave it one coat underneath and i'm just about to duck downstairs to do the 3rd coat on the top but it's already looking pretty suave :) with a bit of luck it'll be nice and dry by tomorrow and we can start putting it back together.


http://www.flickr.com/photos/66195499@N07/6045218898/ by Bonsaichop, on Flickr


... then i'll have another crack at sorting out the sound...
 
Liking the sound yet? :D

I've noticed that this type of amp needs really bass-heavy speakers. That way, it will sound really natural and pleasant. Using weak speakers that normally sound nice with a "normal" Marantz won't work well with these, as Marantz seemed to use some type of design to make up for bass loss in speakers.
 
Ruxman said:
Liking the sound yet? :D

I've noticed that this type of amp needs really bass-heavy speakers. That way, it will sound really natural and pleasant. Using weak speakers that normally sound nice with a "normal" Marantz won't work well with these, as Marantz seemed to use some type of design to make up for bass loss in speakers.
Click to expand...

It's growing on me but you know what, you're absoloutley right. It does need bass-heavy speakers whereas most of my stuff is bookshelf size.

... though..

I picked up a pair of Marantz HD 880's tonight :D once I figure out how to sneak them into the house past my little lady i'll give them a good whirl.

The bad boys in the middle :D
http://akdatabase.org/AKview/displayimage.php?album=1&pos=122
 
Complete!

So while i've been waiting for my several coats of paint to dry on the cover I've had the Marantz plugged up in my office listening to it non stop for a week. The verdict? It is actually quite a great sounding integrated! But it doesn't sound like the earlier Marantz units. I think I've just been listing to the 2xxx and 1xxx series of integrateds' and receivers for too long. My ears were expecting the same warm sound that these deliver. The PM-4 sound is very detailed. It's nice and sharp and really stands out when you're listening to really strong vocals. It's just different to what you would expect from a 70's Marantz unit. Which should be expected as this was an early 80's Esotec series unit.

Going back to my 2220B I've been working, it sounds almost muffled compared to the PM-4. I really think it just caught me off guard when I tried it last time.

The great news is she's all done! Cover is now complete with 4 layers of engine block high temp paint in satin black, followed by 3 coats of clear satin sealer to protect it. And it looks fantastic! Below are the final modeling shots, I did touch up the colour post production because the flash doesn't quite capture it right but I hope you all enjoyed my worklog as much as I enjoyed writing it and working on this wonderful little amp!

Be sure to check out the full restoration gallery on my Flickr Gallery. There's a few more photos that were not included in this worklog.


http://www.flickr.com/photos/66195499@N07/6082741604/ by Bonsaichop, on Flickr

http://www.flickr.com/photos/66195499@N07/6082740324/ by Bonsaichop, on Flickr

http://www.flickr.com/photos/66195499@N07/6082200749/ by Bonsaichop, on Flickr

http://www.flickr.com/photos/66195499@N07/6082741168/ by Bonsaichop, on Flickr

http://www.flickr.com/photos/66195499@N07/6082742052/ by Bonsaichop, on Flickr

http://www.flickr.com/photos/66195499@N07/6082742394/ by Bonsaichop, on Flickr

http://www.flickr.com/photos/66195499@N07/6082202891/ by Bonsaichop, on Flickr

http://www.flickr.com/photos/66195499@N07/6082203311/ by Bonsaichop, on Flickr

http://www.flickr.com/photos/66195499@N07/6082198075/ by Bonsaichop, on Flickr

http://www.flickr.com/photos/66195499@N07/6082199981/ by Bonsaichop, on Flickr

http://www.flickr.com/photos/66195499@N07/6082738452/ by Bonsaichop, on Flickr

\ by Bonsaichop, on Flickr

http://www.flickr.com/photos/66195499@N07/6082739200/ by Bonsaichop, on Flickr

http://www.flickr.com/photos/66195499@N07/6082240179/ by Bonsaichop, on Flickr
 
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This type of amp "ruined" audio for me, because now I cannot enjoy anything inferior, and it is very hard (and expensive) to find something that sounds better.

I still get an urge to get some nice old-fashioned Marantz sound every now and then, though. But not for long listening sessions. Can't take that warmth for extended periods.

Marantz clearly designed those amplifiers to work for everyone, even those not into music or top quality sound. It's like mainstream radio, everyone can like it, to some degree.
 
Yeah you're right, I switched from the 2220B back to the PM-4 after I took the photos and it was like going home. I understand why I didn't like them at first at all, but now I've really messed things up being more critical of the 2xxx sound. Though I do still enjoy it, It doesn't feel the same anymore!


Ruxman said:
This type of amp "ruined" audio for me, because now I cannot enjoy anything inferior, and it is very hard (and expensive) to find something that sounds better.

I still get an urge to get some nice old-fashioned Marantz sound every now and then, though. But not for long listening sessions. Can't take that warmth for extended periods.

Marantz clearly designed those amplifiers to work for everyone, even those not into music or top quality sound. It's like mainstream radio, everyone can like it, to some degree.
Click to expand...
 
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