Marantz 1120 testing

[met_engr]

Happened across a Marantz 1120 for sale by chance yesterday. Previous owner told me it had some channel balance issues and a scratchy volume pot so I'm cautious to let it drive my speakers since I only have one set currently.

I've had some vintage stuff in the past, but nothing I'd invest much time fixing. I think the Marantz is worth the effort so I took a $ chance. Could use some advice on what I should test, clean, fix immediately before hooking up my speakers...and then things to consider down the line.

So far I pulled the jumpers on the back and used the preamp side only. I ran my turntable in and the preamp out to my main system.

I noticed a couple of things playing around today:

- The volume knob was only slightly scratchy. Optimistic a slight cleaning is all it needs.
- No discernible channel imbalance, but the balance fader needs some work. Sounds ok at the mid-detent. Every other position loses a lot of gain.
- EQ actually works, but there's crossfeed (I think that's the term). If I adjust right side base, both sides increase. If I adjust them together the whole system (left and right) sounds equal.
- High and low limiters work well.

The phono stage sounds really really good for what it's worth. I'm eager to get it fully functional now.

 

[tranguru]

One of my favorite amps.... I have 3 sitting next to me right now
keep an eye on the tape 1 & 2 monitor buttons - seems to have some design issue (have fixed on 5 units + many here on AK have had issues with it) - a real pain to fix because you have to dismantle the entire front plate + chassis + remove pcb and de-solder the switches, open them and clean them (a bit fiddly)

luck
robin

 

[met_engr]

Thanks Robin. I'll have to give the tape inputs/outputs a try. Considering this is my first attempt at bringing life back into an old unit I think the less disassembly I have to do the better....so I hope they work ok!

Been down a rabbit hole this morning. Hirscwi points out Marantz used higher end caps in the phono section...maybe that's why it still sounds good on mine?

https://audiokarma.org/forums/index.php?threads/model-1120-full-rebuild-upgrade.620643/

Popped the cover this morning on a whim to have a look around. I don't see any obvious evidence of repairs, but maybe a discernible eye will know better. I did see a capacitor that may be leaking. Called it out with a note in the photos attached.

 

[tranguru]

I would replace those caps.

but take the boards out to do it - to make sure you get clean solder joints.

I could look at these for hours - even though I have a few of those units sitting right next me

 

[met_engr]

I would replace those caps.

but take the boards out to do it - to make sure you get clean solder joints.

I could look at these for hours - even though I have a few of those units sitting right next me

Same here. I'm a mechy so I guess that's what impresses me the most. The mechanical aspect of the unit itself is cool, but just thinking about all the different aspects of production is impressive.... and prior to computers no less. We struggle with supply issues these days with complex inventory databases!

 

[Lavane]

Those axial caps do need replacing for sure. They were leaky in 33 preamp and 16 amp as well. I wouldn't run your amp like that. Depending on the brand used for the main filter caps, they are probably well over due also.

 

[Lavane]

Those main fter caps look like the same brand I had in my model 16's. Sangmo, Sangamo,, or something like that.

 

[met_engr]

Those main fter caps look like the same brand I had in my model 16's. Sangmo, Sangamo,, or something like that.

You are correct. Sangamo 8000 mfd. Hard to get a pic of the markings.

Something tells me I should probably refresh my memory on safely disconnecting caps before trying to replace those things

Look like something on an old air conditioner!

 

[Dingman]

WTF is going on with that relay assembly?
Not saying anything is wrong, but - what am I seeing? I might have to search that up, looks like a relay in series with another set of exposed contacts?

 

[Lavane]

You should think about replacing them as well at some point. But all the others should be replaced first for sure. I ran into a couple cap values you may have a hard time finding in the lower voltages SS gear uses in an axial. I remember having to use a 22uf cap in place of an axial 16uf because a 16uf in the voltage range I needed wasn't available, and even having to parallel a couple . I've also used radial caps in place of Axial caps when I had too. If the 1120 sounds anything like the other earlier Marantz SS separates I've had it should sound really nice once restored.

 

[met_engr]

Obviously those aren't the relays. Haha.

Deleting post to save face...

 

[met_engr]

Sweet. Found the manuals and schematics without any sort of login credentials or registration.

Link for the next guy...

https://www.audioservicemanuals.com/m/marantz/marantz-1120/

 

[Blue Shadow]

What is with the green boards? My 1120 has blue boards.

 

[met_engr]

Found a cap kit online. Is this good or should I keep looking? I think I'll shoot them an email to see if their axial caps or not.

https://www.audio-high-store.com/product/marantz-1120-upgrade-kit-audio-capacitors/

 

[Lavane]

Found a cap kit online. Is this good or should I keep looking? I think I'll shoot them an email to see if their axial caps or not.

https://www.audio-high-store.com/product/marantz-1120-upgrade-kit-audio-capacitors/

It looks like he may be selling radial caps. They will work, but if you want it to l9ok more original, use Axial's. If you do use radial caps, don't bend the leads right up against the seal. Use needle nose pliers and leave a small bit of the leads straight at the seal. Were there any service bulletins with those service manuals? They can be handy if any service updates were made after the 1120 came out depending on the serial number.

 

[Blue Shadow]

Nichicon KZ MUSE, FG Fine Gold, FW, KW
Are what they say is in the kit. All are radial audio grade caps.

Axials are about 10 times the price since there are so few available anymore. I would think that the low value caps could be replaced with a good film cap for less money. I don't think 17% of the audio population would care if you used radial caps but that other 87% of seriously OCD folks would accuse you of blasphemy. Adding to Lavane's comment about the leads, one manufacturer specifies a 30 degree max bend so leaving an eighth inch before the 90 degree bend is a good idea.

I think there are cap lists out there as I saw a couple in my files. I might have made one but the other was probably grabbed from the web.

 

[met_engr]

Nichicon KZ MUSE, FG Fine Gold, FW, KW
Are what they say is in the kit. All are radial audio grade caps.

Axials are about 10 times the price since there are so few available anymore. I would think that the low value caps could be replaced with a good film cap for less money. I don't think 17% of the audio population would care if you used radial caps but that other 87% of seriously OCD folks would accuse you of blasphemy. Adding to Lavane's comment about the leads, one manufacturer specifies a 30 degree max bend so leaving an eighth inch before the 90 degree bend is a good idea.

I think there are cap lists out there as I saw a couple in my files. I might have made one but the other was probably grabbed from the web.

Gotcha. I figured it was too good to be true. If you could point me towards a list/BOM I'd appreciate it. Haven't found one yet.

I would like to stick with axial caps, if possible.

Saw in another thread someone replaced the transistors too. Should I be shopping for those as well?

 

[Blue Shadow]

I have not gone to Digikey/Mouser and filled in the replacements, yet but from actually looking inside my unit and writing down what I saw:

Marantz 1120
C113/114 PS caps
Phono Selector Board Front to Back
C201 x 1/250
C202 x 1/250
C203 x 1/250
C204 x 1/250
209 47/10
210 47/10
213 6.8/10
214 6.8/10
Tone Board
C303 1/250
C304 1/250
C305/306 0.22/250 check it
C307/308 0.1/100
C309 10/25
C310 10/25
Power Amp
C501 10/20
C502 10/20
C505 50/40
C506 50/40
C509 50/6.4
C510 50/6.4
C511 100/40
C512 100/40
C516/517 0.1/250
C519/520 0.1/250
C401 680/25
C402 680/25
C403 0.1/100
C404 0.1/100
C405 150/25
C406 150/25
C407 150/40
C408 150/40
C409 220/63*
C410 220/63*
C411 220/63*
C412 220/63* could be 330
C413 150/25
C414 33/16
C415 10/63

Shouldn't be hard to roll over to those sites and look over the slim pickins for axial caps and find what they have that fits and finish the list with radials as needed. I really need to get back to this project.

 

[dankik]

The Marantz 1120 SM has a parts list and nice board photos with parts identifiers. Why don't you start with this instead of a visual list? Some of the cap tolerances are 5% or 10%, not the usual 20%. I don't know if this SM is what you found, but I got this from hifiengine.com.
See example below:



Just check a few of these at Mouser and they have the ones I checked in stock now, but as the OP said they are not cheap.
Also, there are some caps on the other boards that are large axials, but not listed as electrolytics in the PL and not shown with a "+" on the schematic (but has a ---)!--- symbol on the schematic)... need to check if these are not polarized?

 

[met_engr]

See example below:

Just check a few of these at Mouser and they have the ones I checked in stock now, but as the OP said they are not cheap.

Appreciate the advice. Being a novice I'm concerned I'll choose the wrong capacitors to be honest. Thinking this is a learning opportunity though. When you're searching Mouser are you only searching by axial leads and then looking for caps with equal mfd (with an equal to or higher voltage rating)...or is there more to consider when choosing a cap?

Also, I've seen mentioned there are "known errors" in the service manual. Is that something to consider or can I just use the lists as is?

I did find a paragraph referencing a diagram and explained the diagram only showed the left channel, but the right was equivalent. The diagram showed left and right though. I was pretty confused for about 3 minutes! Sometimes an obvious error like that is kinda like a Van Halen brown m&m clause....