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2270

HBrown

HBrown

Active Member
2270 Project

I'm beginning to look at a 2270 picked up VERY reasonable which has a MISSING volume pot/knob.
Haven't even thought about powering it up sans pot. Guy it came from says it powers up, but he couldn't test it cause the knob was missing. Turns out the pot itself is missing. Gonna tear into it later and see what I can see. Anybody wanna enlighten me as to hard to find a pot is? Are replacements available? Am I looking at having to go with a used one from the bay? Lord knows what I'm gonna find under the hood.
 
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I could not find a new replacement, but that doesn't mean they aren't available. Used pots are not all that hard to find. Getting one for a reasonable price is a bit more difficult. I suspect that a pot form a 2270 would carry a premium as compared to some less popular models. There are usually several to choose from on the auction site. It does not necessarily need to be from a 2270. It does need to be 250kohm - audio taper (vs. linear taper, which is used for example on a balance pot). And it needs a separate tap for the loudness circuit. Some models use a 50kohm pot, which will not work.

I have had good luck interchanging from a couple models. I even used the volume pot from a 4 channel (4240 I think) on a 2325 by cutting off two sections. If it indicates 250kohm and was a volume pot on a Marantz, there's a good chance it will work.
 
I have asked a local supplier of used parts, to see if they have one.
Getting an original is the best option. But if that does not pan out for you, you can sub as "hirscwi" has mentioned.
Problem is, if the pot is not 250K and tapped at the same part of the wiper, then the loudness compensation network will be off. So if you use a different value of pot, then look at the schematic of the model that it came from and duplicate its loudness compensation network. On the 2270 it is on P650. It is a simple RC network, 2 caps a nd 2 R's.

If you do not require the loudness feature then practically any pot from say 50K to 250K will work. (use the tone controls to do the same thing)
You do want a audio taper pot however.
here are a few options
http://ca.mouser.com/Passive-Compon...1yzokfjZ1yzrybd&Keyword=potentiometer&FS=True

Rick
 
Thanks for the responses. I'm crossing my fingers- a local guy is checking- thinks he may have a pot. In the meantime I have noticed some components on the protection board near the relay appear to be missing- empty solder holes- I'm trying to get the schematic printed and identify the components. If I had to guess this unit was stopped in mid repair by someone else- there are sharpy notes written all inside the chassis identifying parts. The missing parts suggests that further repairs were declined- or else it became a parts unit. Guy I got it from didn't know any history on it- it was in a lot of stuff he bought. He said he tried to power it up and the face lights up so there may be hope for it.
 
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Shoot a picture of the board and post it. We'll chime in with whether or not anything is missing. Sometimes the same board is designed to fit several usages/models so it would be normal for some parts to be missing.

In order to hook up with the very generous offer made by whld1610, you'll need to be a subscriber. That info can be found on the home page I believe. Well worth it IMHO.
 
I am re-building an old Kenwood KR-5030/5330,
so I am getting my BOM together, based on the schematic & parts list, see my example, as below, just the PS section. Always good to look at the pcb to verify as sometimes the pcb does not match the docs.
Then I create a project in Mouser project manager and go to work.

Audio (X09-1240-10 B/2) (Power Supply Section)
Cm49,50:10,000uF/50V (ale-pol) 35x80mm 2-pin tab
667-ECE-T1JA183EA (Snap In 18000UF 63V ELECT THA)

Cm52:22u/50V (ale-pol) use 47uF/63-100V
667-EEU-FR1J470 (Aluminum Electrolytic Capacitors - Leaded 63volt 47uF 6.3X11mm LS:2.5mm Bulk Strait)
667-EEU-FR1J470B

Cm53:100u/50V (ale-pol) use 220-470uF/63-100V
667-EEU-FR1J221L (Aluminum Electrolytic Capacitors - Leaded 63volt 220uF 10X25mm LS:5mm Bulk Strait)
667-EEU-FR1J221LB

Cm55:220uF/16V (ale-pol) use 220-470uF/25V
667-EEU-FR1E331 (Aluminum Electrolytic Capacitors - Leaded 25VDC 330uF 8x11mm LS3.5mm )

Cm56:100uF/16V (ale-pol) use 470u/25V

Cm57,58:220uF/35V (ale-pol) use 470uF/35V

Dm15:M4C-3 (200V/10A bridge? with heatsink)
Dm17:WO6B
Dm18:YZ-140 (14V zener glass 500mW)

Dm19,20: WZ-240 (24V zener glass,DO-41)
512-1N4749ATR

Qm25:2SC789(Toshiba,70V,4A,30W@25Ccase,hfe=40-240A0.5A,Ft=3MHzTO-220AB)
512-KSD363YTU (BCE)
Click to expand...
In the meantime I have noticed some components on the protection board near the relay appear to be missing- empty solder holes-
Click to expand...
Check against the assembly drawing too, I know it is hard to figure out based on those photo-copies.
 
pics

Boards are pretty dirty on topside of chassis. It's missing the feet also. When I went to look at it, it was the first Marantz unit I have had my hands on. Right now I'm missing the vol pot, volume knob, & chassis feet for sure. I don't see anything burned so far. My perception is this is a fairly early 2270. Where would the date of manufacture be?
 

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If it's an early model as serial # indicates! it may be an champaign engraved face version, which adds to value. If that's the case, and it's cheap, I'd definitely pick it up and restored it.
 
Compare your unit against the two schematics from hifiengine, see what one matches, hopefully it is one of them.
2270_service_full.pdf
and
2270_service.pdf
There are very noticeable differences when I take a quick look at them.
 
pics

Faceplate detail... I guess that's engraved? I can feel the lettering is recessed. Pretty sure this one is silver color- but under a different light it looks different...
 

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Indeed it's engraved, doesn't look champagne so it's even rarer. There was a run of champagne which are less common, a run of silver engraved which are even less common and the rest that were standard 2270's. I'd buy that unit in a heartbeat and completely redo it.
 
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My guy came through with a 250 k pot from 'a marantz receiver'. Got to dig into the manual and see which part number its supposed to be in the 2270.
 
pot pic

Ok- I'll be a monkeys uncle. The pot the guy came up with appears to be correct- I'm gonna soak it in deoxit and try to figure out which wires go where. Probably gonna have to 'rewire' cause it looks like they just cut the old pot off with no regard for the wires.
 

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That's generally how you pull a pot for somebody. Just remove the solder from the eyelets and the wire will come with it. Desolder the old pot from your 2270 and install to the new pot one wire at a time.
 
That's the thing- the pot was MISSING from the unit- I had to find one. Unbelievably, a guy local to me happened to have one. Some of the wires left in my unit are cut off too short to reach- gonna have to replace a few of them after I figure out what goes where.
 
Ah ok, well , if you aren't in a super hot rush I can pull the bottom of my unit off and tell you what wire goes where tomorrow.
 
Thanks bkthking- no, I'm in no hurry. Tell you what though- before you do that, let me study whats left of the wires there and the schematics and then if if I can't get comfortable with what goes where I may take you up on that offer. Thanks.
 
HBrown said:
Boards are pretty dirty on topside of chassis. It's missing the feet also. When I went to look at it, it was the first Marantz unit I have had my hands on. Right now I'm missing the vol pot, volume knob, & chassis feet for sure. I don't see anything burned so far. My perception is this is a fairly early 2270. Where would the date of manufacture be?
Click to expand...

Looks to me like the wire colors and locations are written all over the IF strip cover in felt pen.

You are missing transistors H809 and 810 on that power supply board. I bet the relay wouldn't click and these were suspected. If the amps are otherwise working I've seen these go leaky but usually it's a bad cap C807 (220uF). So I recommend ordering these (Mouser part numbers):

C807: 647-UHE1E221MPD
H809/10: 512-KSC2383YTA (as recommended by avionic - thx!) Check the pinouts per the datasheet (link is on the Mouser web page) for pin orientation, you mave have to rotate and or cross legs to get the legs in the correct holes. Use insulation if legs get crossed.

It could easily be that one or both amps are bad which would also keep the relay from clicking on. That's a whole other layer of fun! :D
 
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