Marantz 4270 newest victim

Richs_Trains

AK Subscriber
Subscriber
Hey all,

In my crazy effort to aqquire every Marantz quad, I picked up a 4270 with a wood case. The 4270 arrived in one piece, the wood case, not so much. Anyway, thank goodness this one worked when I got it, just needed the usual de-oxit treatments and general cleaning. I have re-capped the power supply (most were jumping out of their skins!) and both amps and for once did notice a significant change in sound, mostly after re-capping the power supply. I have order filter caps and hope to have them by next week. Unfortunately, the unit came with no metal cover and the wood case is marginal (even after re-gluing it and filling in the missing pieces with wood putty), so I had to find one on the bay. Hate it that people cut up good machines for parts just to make money, but I have to admit they have saved my a** a few times. Anyway here's the picts till now...
4270_1.jpg
4270_3.jpg
4270_2.jpg

Thanks... Rich
 
Those Marantz quads sure do have a high knob/button count. Something to like about that.
 
Hi Rich, did you make a parts list for this unit and if so do you mind sharing? I supposedly have one incoming with a few issues, not sure if a simple deoxit and new relays will cure it or if it has more issues.

Good show saving that one, hope it sounds as good as it looks!
 
That's going to be a nice one. It's going to look great in a wood case. Keep us up to date on the progress! :thumbsup:
 
Hi Rich, did you make a parts list for this unit and if so do you mind sharing?


Sorry N8Nagel,

I don't have a list, I just have bins with a lot of the caps Marantz' use, so I usually go value for value. I actually thought I didn't have the axial 220uf 50v on the power amp, but had 4 in the drawer. I have heard it recommended to use 105C caps on the power supply (I only used 85C nichions) and that the relays are very difficult to replace. I use pretty much all nichion audio caps, but I really think any quality modern caps is an improvement. It sounds pretty good on the 'bench' (kitchen table) and when I get the metal cover and the filter caps, I think I'm going to put it in place of my 4070 quad in the living room. Thanks Rich
 

Sorry N8Nagel,

I don't have a list, I just have bins with a lot of the caps Marantz' use, so I usually go value for value. I actually thought I didn't have the axial 220uf 50v on the power amp, but had 4 in the drawer. I have heard it recommended to use 105C caps on the power supply (I only used 85C nichions) and that the relays are very difficult to replace. I use pretty much all nichion audio caps, but I really think any quality modern caps is an improvement. It sounds pretty good on the 'bench' (kitchen table) and when I get the metal cover and the filter caps, I think I'm going to put it in place of my 4070 quad in the living room. Thanks Rich

These receivers sound really good. Got my first one free from a customer! Said his kid blew it up. He blew the speakers. It was sad looking. The face was black. After. Good cleaning,replacement lights..good to go. Used it as my bench amp for a month. Too good to stay there. Moved to the livingroom. Putting it there is a good idea. Mine is hooked to JBL L100s up front with small Pioneeres on the back. Have two Dual's for music. It really sounds great. You will not be disappointed! I like it so much, I bought a second 4270 that lives in my bedroom hooked to a pr of ADS 810s. End most days playing a record on another Dual turntable. Enjoy! I really like quads and receivers. The lights are really cool. Moved the Marantz 2252 to the bench. It's no slouch, down in the shop. It's my test amp. Running a Dual 601 there, plus a Garrard SL 95 that is a study on how to get to work. Down to auto start not working. It will shut off automatically, but not it I move the lever...another story. Enjoy your 4270. I have owned many systems over the years and both 4270s are the best!

Eric
 
Finished the 4270 tonight when the filter caps came in, first ones I ordered were too tall (been checking the diameter, I guess I'll have to check the height now also!). Sounds great, looks good in the wood case, going to hook it up in place of the 4070 tomorrow and take a picture for AK. Thanks for your help AK ... Rich
 
The 4270 never came with a metal top, atleast the two I've seen and the one I own didn't. The wood case IS the case for the unit.
 
That looks way nicer than the one that arrived on my desk today:

y4m29A59A7ML74qjGyl7rkU2uYu7qMkNTf-cpkp_mWcwfuj8ICtwYq0P1vlCByE5bTxWHQ8SSXgjgPVAZakcTU7hVY8gLXFxwlMb1_Bv4EBe32qNOfooQJWTnue0oLcs4QzbjT5n5R7v4OO7UAQTpvKW0qynD_ZuT0ZyJLesQ4z6c9C2akuRO3pMDDlDSjTwccIrRjZJWao8YecWFE3vtl7gg


This one's had a hard life and has 180mv DC offset on left channel. Also power button is stuck ON. And it had a metal case top that was crudely modified to fit.

Hints on correcting offset welcomed.
 
The 4270 never came with a metal top, atleast the two I've seen and the one I own didn't. The wood case IS the case for the unit.
I have one at home with a metal cover. It had a wood case when I bought it. Sometimes folks would remove the metal cover when installing into a wood case.
 
...Hints on correcting offset welcomed.

I'd suggest replacing either the H701/H703 differential pair or H702/H704 depending on which channel is off. Use KSA992 and gain (Hfe) match them. It's a start anyway!
 
The 4270 never came with a metal top, atleast the two I've seen and the one I own didn't. The wood case IS the case for the unit.

Mine has a metal case, I don't know if it is original or not, but it looks it.

FWIW mine has the small Phillips screws on the faceplate not the big hex bolts (I've seen both, don't know which was earlier or later or if Marantz just used whatever was around.)
 
Mine has the phillips screws too. I assumed those were incorrect. But I don't know much.
 
Interesting! Looking at the faceplate on my 4270 there's no scratches that would indicate that the larger hex head screws were ever there. So it's likely an early one.
 
I'd suggest replacing either the H701/H703 differential pair or H702/H704 depending on which channel is off. Use KSA992 and gain (Hfe) match them. It's a start anyway!

OK so there is no adjustment that affects offset on these - it's just the balance between the pair of transistors.
I don't want to get into this thing for a lot of $ without knowing that it's basically working. But those transistors are pretty cheap...
 
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