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Marantz 2270 refurbish

HVHiFI

HVHiFI

Hudson Valley HiFI
Sponsor
I was asked for a fairly detailed 2270 restoration thread. I recently was sent two of them to be serviced. I will post a bunch of pics of the first which is almost complete, then as I do the second any detailed pics anyone may want can be added.

First, condition wise this pair are within 1000 serial numbers of each other, mid 20000s. They both work, but are both not to factory spec. On the scope with an 8 ohm load they are pushing around 42-50 watts maximum out of each channel. Clean waveforms and will not clip even at maximum volume. I am sure the electrolytics are tired and should have some other updates as well.

I will post pics and descriptions as I go along. For this work Panasonic supply filter caps, Nichicon electrolytics PW and KL series, and Panasonic stacked films will be used.
 
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Power supply before shot, speaker relay foil side, and after shots. Nichicon PW used for high temp and new Omron MY2 relay.
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Phono preamp. Film caps changed to Panasonic film. Tantalums and electrolytics changed to Nichicon KL. Pair of transistors on sides of large electrolytic changed as well.
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Tone board. This board is easier to access if you remove the faceplate and release the tone controls board above this board. It allows the board to turn more free. Note, none of these boards need to be removed to service. This board gets an array of Nichicon KL and Panasonic film subs for the 1uf elec.
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With the faceplate off cleaned the cigarette tar and gunk off. Dial removed and all lamps replaced. Owner wanted incandescent replacements but new vellum. Once back together here is the finished face and a shot of the old vs new vellum. If your wondering why your Marantz dial is green looking this is why. The amp boards are next to be done and will be posted soon as they are.
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She's looking good Mike.
I appreciate the running description as you go through the photos of the various boards. Very instructive. I'm anxious for the adjustment process.
Thanks much.:thmbsp:
 
Nice!

40 to 50 wpc is about half of a correctly operating 2270. You might want to double check that.

Jk
 
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HVHiFI said:
With the faceplate off cleaned the cigarette tar and gunk off. Dial removed and all lamps replaced. Owner wanted incandescent replacements but new vellum. Once back together here is the finished face and a shot of the old vs new vellum. If your wondering why your Marantz dial is green looking this is why. The amp boards are next to be done and will be posted soon as they are.
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Click to expand...

Nicely done.

When I look at the lower picture in post #8, I see some slightly brighter spots where the lamps would be behind the dial.

One of my 2270's looks just like that (and blue not green). It came this way and I thought someone may have put slightly brighter bulbs when/if he re-lamped. Maybe 8v/250 (or 300?) vs 8v/200mA.

Can you tell me what value the ones you are using are?

Thanks.
 
PB - thanks for the kind words. Yes, I will show with details biasing the amp section.

JK - thank you also, yes, the 2270 factory spec was 70wpc but it is not uncommon to see them push 90 watts before clipping. I should have specified, pre-service testing showed both only putting out 40-50wpc. I have not tested since the work has been done. I am hoping we are back up to exceeding factory spec when these are finished. Always rewarding see them back to their former glory.

Onemug - Thank you. The bulbs I use are from Dave (AKer Dgwojo) as he is THE man for lamps. I replaced all the fuse style lamps in the dial and meters. They are 8v/200mA. What you are describing is what it is for lack of better term. The lamps since they are incandescent will be a tad brighter in the middles. This client wanted then over LED for that reason. He is an original owner and he wants it like day one. I have seen and done LED conversions and it looks sharp as well. I do as the client wants. Obviously, LED has it's advantages as well in longer life and almost no heat. I think increasing the mA of the lamp may cause even more heat and possible problems. Perhaps someone can bring more info on that for you.
 
HVHiFI said:
PB - thanks for the kind words. Yes, I will show with details biasing the amp section.

JK - thank you also, yes, the 2270 factory spec was 70wpc but it is not uncommon to see them push 90 watts before clipping. I should have specified, pre-service testing showed both only putting out 40-50wpc. I have not tested since the work has been done. I am hoping we are back up to exceeding factory spec when these are finished. Always rewarding see them back to their former glory.

Onemug - Thank you. The bulbs I use are from Dave (AKer Dgwojo) as he is THE man for lamps. I replaced all the fuse style lamps in the dial and meters. They are 8v/200mA. What you are describing is what it is for lack of better term. The lamps since they are incandescent will be a tad brighter in the middles. This client wanted then over LED for that reason. He is an original owner and he wants it like day one. I have seen and done LED conversions and it looks sharp as well. I do as the client wants. Obviously, LED has it's advantages as well in longer life and almost no heat. I think increasing the mA of the lamp may cause even more heat and possible problems. Perhaps someone can bring more info on that for you.
Click to expand...

Would you believe that High Fidelity Mag measured the 2270 Power @ 103WATTS/Ch-RMS 20~20KHz at less than .05% THD and IMD.
Yes, Marantz specs were very conservative back then.
Slightly less so in the 2275 and 2285... all of which made essentially the same POWER.

Regarding the fuse lamps... has anyone been able to source an 8v 150ma version of this fuse lamp? I'd personally prefer to tone the display down a notch.
 
HVHiFI said:
PB - thanks for the kind words. Yes, I will show with details biasing the amp section.

JK - thank you also, yes, the 2270 factory spec was 70wpc but it is not uncommon to see them push 90 watts before clipping. I should have specified, pre-service testing showed both only putting out 40-50wpc. I have not tested since the work has been done. I am hoping we are back up to exceeding factory spec when these are finished. Always rewarding see them back to their former glory.

Onemug - Thank you. The bulbs I use are from Dave (AKer Dgwojo) as he is THE man for lamps. I replaced all the fuse style lamps in the dial and meters. They are 8v/200mA. What you are describing is what it is for lack of better term. The lamps since they are incandescent will be a tad brighter in the middles. This client wanted then over LED for that reason. He is an original owner and he wants it like day one. I have seen and done LED conversions and it looks sharp as well. I do as the client wants. Obviously, LED has it's advantages as well in longer life and almost no heat. I think increasing the mA of the lamp may cause even more heat and possible problems. Perhaps someone can bring more info on that for you.
Click to expand...


Thanks. I have bought from Dave, agree he is excellent.

I have incandescents in all 3 of my 2270's. 2 of them have the dial lit evenly, the 3rd has the slightly brighter spots. Haven't opened the 3rd one up to check the values. All the bulbs are working.

I also thought that maybe the velum, in my 3rd, could be a little thin in those areas but you said you replaced the velum in yours and with the factory correct bulbs and it still has some brighter spots so who knows.

Not a big deal.
 
I just got my hands on a 2270 and 2230B. I've never owned a 70's Marantz but have been a bit obsessed with them recently. I'm at work and haven't been able to test them out yet. What is a ballpark idea of what I should expect to spend to have them cleaned/tuned as long as no major parts need replaced? What should I expect for a full bore restoration (recapping, etc.)?

Thanks in advance...you definitely seem to know your way around these!
 
Hi pnw, and welcome to AK. Two very nice receivers. Give them a listen and see if there is anything obvious wrong with them. Static, popping, or uneven channels you can hear easily. Many of them still sound good but are just lacking the power due to aging components weakening the amp. Some are still pushing out over factory spec nearing 40 years old! A good restoration is clutch to keeping them playing on reliably. I don't like talking estimates in informative threads, my email is mike@hudsonvalleyhifi.com , you can message me anytime. Thanks!
 
Amp boards : much easier to access if you take the time to remove the heat sink and outputs as in the first pic. Replaced the electrolytics and tantalum with Nichicon KL. Inspected, cleaned, and lubed the variable resistors. Reinstalled outputs with new thermal paste and back together. This receiver had the service done to remove the 2SC984B and replace with a 2SC496 so no need to do the service bulletin. The next 2270 did not have the replacement so it will be done. I have some modern ON-Semi transistors to replace it.
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Amp alignment : Three adjustments were made here. First up was the power supply / protection board. Put your meter between J802 and J803 and adjust R809 for 35VDC.
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Next, DC offset, hook your meter to each set of speaker terminals and adjust R762 variable resistor for as close to zero you can possibly get.
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On to idle current. This 2270 is a 26xxx serial number so you put the meter between J756 and J754. Adjust R763 variable resistor for 5mVDC.
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After 15-20 min recheck and readjust if needed.

Once in check, with an 8 ohm load, 1kHz sine wave, amp is now pushing 86wpc before clipping.
 
HVHiFI thanks for taking the time and effort to post the details of your 2270 refurbishment you have done a great job and I'm enjoying following your thread. :thmbsp:

I'm particularly interested as I just (mostly) finished restoring my 2245 and had taken a lot of before and after pictures with the intent of posting them as I went along but never got around to it.
 
Hey Rasputin, thank you, post them up and any curves it threw at you in the process. I not only want to show my work but also encourage anyone doing their own restore.
 
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