Marantz 1200- should I recap?

mcheinstein

Active Member
Hi everyone, first time posting!

I just got picked up a Marantz 1200 integrated amp and 120 tuner from a single owner who barely used the two units (only $300!). They look nearly in mint condition minus some dirt on the face plates I can clean pretty easily.

marantz stack.jpg

here's the inside of the 1200
marantz 1200 inside.jpg

I've never heard one of these units before, so I have little baseline, but, to my ears, the unit really sings. It sounds truly amazing, giving new life to songs I've listened to hundreds of times.

I'm definitely planning to do a full deoxit on the pots (the left/right pot is a little scratchy), switches, and jacks.

I'm wondering though whether I should be planning to do some serious recapping on the unit. And, if so, which caps should I prioritize? In other posts, people seem to prioritize the electrolytic caps on various boards. I have the schematics for the whole thing, but unsure where to start.

I have a lot of experience soldering and circuit building (PhD in neuroscience) and I have access to a variac and a capacitor checker, so I should have the tools necessary. But, I've never worked on high end audio appliances before.

TLDR: Great condition 1200 integrated amp. To recap or not? If so, what should I prioritize?
 
Suit yourself but if it sounds good run it for a while.There is no reason to replace caps unless they don't pass spec, and or the amp has sonic issues that reveal the caps are bad...when you open it up look for swollen or bleeding caps, they need changing , but have it checked before you change stuff out..you got a great deal so keep it that way....if it sounds right it's right...
 
That amp has all axial caps except for the main filter caps.

I just repaired one.

You won't "see" and bad caps. Why does anyone think they can do that? You won't see any "leaking" either. Where did that dumb idea come from?

Bad caps have lousy ESR and you need good test gear to even test that. If you take a cap out to test it, why put it back!?!?! Just replace it. They're cheap and you don't have a proper cap tester.

The amps are a tad tricky because the output sockets are not board mounted. Taking the outputs out to replace the caps gets tricky when trying to get the outputs back in correctly. The sockets need to locate in the holes in the heat sinks properly.

You need a Variac and watt meter to adjust the amp bias. The amps need to be removed to adjust them.

I rebuilt the protection circuit and recapped the relay board, that was the issue. I would do a full recap but the owner is a cheap ass. I hit the tone board with a recap because I had it out to fix a bad solder joint on the connector.

Note, the boards are not marked so watch how things are oriented before removing them!
 
Suit yourself but if it sounds good run it for a while.There is no reason to replace caps unless they don't pass spec,


if it sounds right it's right...

The first part is OK.

That last line? Never saw that in any service manual ever.
 
That amp has all axial caps except for the main filter caps.

I just repaired one.

You won't "see" and bad caps. Why does anyone think they can do that? You won't see any "leaking" either. Where did that dumb idea come from?

Bad caps have lousy ESR and you need good test gear to even test that. If you take a cap out to test it, why put it back!?!?! Just replace it. They're cheap and you don't have a proper cap tester.

The amps are a tad tricky because the output sockets are not board mounted. Taking the outputs out to replace the caps gets tricky when trying to get the outputs back in correctly. The sockets need to locate in the holes in the heat sinks properly.

You need a Variac and watt meter to adjust the amp bias. The amps need to be removed to adjust them.

I rebuilt the protection circuit and recapped the relay board, that was the issue. I would do a full recap but the owner is a cheap ass. I hit the tone board with a recap because I had it out to fix a bad solder joint on the connector.

Note, the boards are not marked so watch how things are oriented before removing them!

This is photo of two of the caps from my 2440 I just replaced along with 4 other that had leaked fluid and no longer tested at spec.

Below is a couple of links to the dozens of articles online about visually inspecting caps and leakage issues, both electrical leakage and fluid leakage.

Further below are photos of caps that have swollen up up and leaked out fluid from the seams....

I'm not a fool regarding advice and further once you have trained your ears enough you will notice the signs of bad caps pretty quickly by listening as well as testing...

image.jpg

http://www.capacitorlab.com/visible-failures/

http://www.vintagesilversmith.com/Marantz/2385/filters/2385_filters.himage.jpgimage.jpeg
 
If it sounds right it is right ... Is one of the oldest axioms of experienced sound engineers...once your critical listening is honed from years of work, ( no not damaged by volume levels, I'm talking about people a little farther up the food chain) you will hear anomalies that clue you in that all isn't right..
 
This is photo of two of the caps from my 2440 I just replaced along with 4 other that had leaked fluid and no longer tested at spec.

Below is a couple of links to the dozens of articles online about visually inspecting caps and leakage issues, both electrical leakage and fluid leakage.

Further below are photos of caps that have swollen up up and leaked out fluid from the seams....

I'm not a fool regarding advice and further once you have trained your ears enough you will notice the signs of bad caps pretty quickly by listening as well as testing...

View attachment 893682

http://www.capacitorlab.com/visible-failures/

http://www.vintagesilversmith.com/Marantz/2385/filters/2385_filters.hView attachment 893685View attachment 893684

Top photo is assembly glue.
Bottom photos are capacitor plague. Only found on certain years when those crap caps were used. You won't find that in 70s vintage.

Yes, its possible to hear bad things going on.
I will not accept "sounds good-is good" as a valid test on operational condition.
It may be fine for sound engineers dialing in the sound on good gear, not a valid assessment of the gear. Sorry, I disagree.
 
Thank you Blhagstrom and FOH engineer for your thoughtful responses. Very interested in blhag's opinion given you've just repaired one.

I have a variac and wattmeter, and I plan to adjust the bias tonight.

Given your thoughts, and correct me if I'm wrong, it sounds like you recommend a substantial recapping, which I am not opposed to. My ears are not terrible, it sounds good and confirmed it with someone else I trust.

I guess my question boils down to: if I were to start recapping the beast, are there any common trouble makers in this unit I should make a bee-line for? Or, is it that there are limited ways of knowing which ones are bad (given that I can't explicitly hear where defects may be coming from), and I should indiscriminately recap as completely as possible? Or something in the middle?

Thanks!
 
T
Top photo is assembly glue.
Bottom photos are capacitor plague. Only found on certain years when those crap caps were used. You won't find that in 70s vintage.

Yes, its possible to hear bad things going on.
I will not accept "sounds good-is good" as a valid test on operational condition.
It may be fine for sound engineers dialing in the sound on good gear, not a valid assessment of the gear. Sorry, I disagree.[/QUOTE

Thats fine, but you said caps dont swell or leak.in fact they do, I changed out a handfull on a rough but fixable Marantz 140 all original and all showed signs of internal leakeage , swelling casing ..I wouldnt change anything until it tested as out of spec...or the amp had sonic issues indicating trouble..
 
Though not always successful, I try to use the terms "DC leakage" when talking about electrical properties of caps. "Venting" or "Rupture" is another good term that applies to the pix above. I've only seen it on computer boards, but the capacitor plague did affect a lot of stuff during a certain time period.
 
The 1200 was my favorite Marantz piece of all time. It has both the 3300 preamp and the 250 power amp. And not just watered down versions of both but real fully blown versions of both (should never use that word blown in electronics).

Ok I'm going to give it to you straight. The 250 on top of being one of the best all time amps in history is also known as one of the most unstable amps in history. What that mean isn't that it's going to blow up on you. But what it DOES MEAN!~!!!! is when you go to restore it you may never get it working again. How do I know that - just do a search and from personal experience.

I plan on doing a posting of how Bob Speece did my Marantz 250M rebuild. There you will see what needs to really go into these things to restore them properly.

Listen to it, use it, enjoy it, but PLEASE don't try to rebuild it yourself. Even with some electronic knowledge the 250 HAS stumped the best of us.
Picture of Bob adding after market bulletin update fly back diodes
Marantz 250 diode.jpg
marantz 250 on semi.jpg

Picture of Bob adding new OnSemi MJE21195/96 output transistors installed on their heatsinks with new mica insulators and Dow 340 heatsink compound.


Marant 250 caps and resistor.jpg

Now READ THIS. this is the email from Bob explaining some of the things he did.

"I replaced the drivers with new correctly matched 2SC783 and 2SA483's with new mica insulators and Dow 340 heatsink compound making sure that the small nylon spacers were in place.

I replaced the predrivers with new matched ST 2N3440 and 2N5416's.

I replaced the differential input pair with matched and heatshrink bonded MPS6519's.

Used Vishay AML138 for the axial caps and a Panasonic FC for the 100uf tantalum C527.


Tomorrow I plan on working on the right channel amp board with the same treatment.

Those oem original type Toshiba TO66 and ST 3440/5416 transistors are rare and hard to source but they are the best and look far better than shoehorning in some TO220's like others do.
 
Heard loud and clear. I really don't want to mess this thing up. Sounds like I should keep it as is, and, if I have problems, I'll consult with a professional. My experience is all with much newer equipment where I have had a lot more resources/knowledge base/equipment on hand. Doesn't sound like this should be my first rodeo in vintage audio.

Thanks for your input, I do appreciate it!
 
I have a 1200B in for a rebuild and they are very similar to the (non-B) 1200. I know because I've rebuilt one of those too. The 1200B is humming and for sure one or more caps on the board that is full of larger axial caps (470uF from memory) is/are open circuit as observed on an o-scope. The ends of all of them are visually swollen out. So I recommend at least recapping this board. I'll be using the much respected Vishay AML138 series axial caps on my job. I know of the series thanks to good pal, Tom AKA Catrafter.
 
Thank you Blhagstrom and FOH engineer for your thoughtful responses. Very interested in blhag's opinion given you've just repaired one.

I have a variac and wattmeter, and I plan to adjust the bias tonight.

Given your thoughts, and correct me if I'm wrong, it sounds like you recommend a substantial recapping, which I am not opposed to. My ears are not terrible, it sounds good and confirmed it with someone else I trust.

I guess my question boils down to: if I were to start recapping the beast, are there any common trouble makers in this unit I should make a bee-line for? Or, is it that there are limited ways of knowing which ones are bad (given that I can't explicitly hear where defects may be coming from), and I should indiscriminately recap as completely as possible? Or something in the middle?

Thanks!

Fairly sure the unit is rare enough that there is little "known" trouble makers.

Given the age, new fresh caps are not a bad move.
As noted, the caps are all axial except for the filter caps and it would be a shame not to use axial.
Replacing them is simple, but note that the boards are not marked so YOU need to maintain correct orientation.
I noted the challenge about accessing the amp boards. Those loose output sockets are tricky.

I think its a worthy amp for a refresh on the caps.
I've done enough full recaps to know that the reward is there and this amp is not as difficult and many other things.

The one I fixed had problems coming out of protection.
It would buzz and struggle to :"snap" in.
Replacing the caps and protection transistors on the relay board has cleared up the problem.
All the replaced parts test good on test gear. They just don't work well in circuit.
I have repaired too many things where the parts test good but the unit doesn't work to bother putting old parts back in, especially caps.
 
Though not always successful, I try to use the terms "DC leakage" when talking about electrical properties of caps. "Venting" or "Rupture" is another good term that applies to the pix above. I've only seen it on computer boards, but the capacitor plague did affect a lot of stuff during a certain time period.

1999-2007

https://en.wikipedia.org/wiki/Capacitor_plague

Electrolytic capacitor info

https://en.wikipedia.org/wiki/Electrolytic_capacitor

Hmmm, found a new doc online. You got to love Google.

http://www.cde.com/resources/catalogs/AEappGUIDE.pdf
 
I hadn't see that CDE doc before- excellent and should be required reading. Very complete, good depth and well organized.
 
I have a 1200B in for a rebuild and they are very similar to the (non-B) 1200. I know because I've rebuilt one of those too. The 1200B is humming and for sure one or more caps on the board that is full of larger axial caps (470uF from memory) is/are open circuit as observed on an o-scope. The ends of all of them are visually swollen out. So I recommend at least recapping this board. I'll be using the much respected Vishay AML138 series axial caps on my job. I know of the series thanks to good pal, Tom AKA Catrafter.

Thanks for the info. Yes the ps board component assembly is the one with 6 large axials that are 470uF. I'll take a look at them tonight.

Fairly sure the unit is rare enough that there is little "known" trouble makers.

Given the age, new fresh caps are not a bad move.
As noted, the caps are all axial except for the filter caps and it would be a shame not to use axial.
Replacing them is simple, but note that the boards are not marked so YOU need to maintain correct orientation.
I noted the challenge about accessing the amp boards. Those loose output sockets are tricky.

I think its a worthy amp for a refresh on the caps.
I've done enough full recaps to know that the reward is there and this amp is not as difficult and many other things.

All the replaced parts test good on test gear. They just don't work well in circuit.
I have repaired too many things where the parts test good but the unit doesn't work to bother putting old parts back in, especially caps.

Thanks, blhagstrom, for your thoughts, esp. on keeping track of the board orientation. If i do work on this thing, I will be extremely diligent with taking photos and making notes of everything as I go.
 
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