SR-2000 / STK080G /Cicon Electronics

Kevin K7ZS

Kevin K7ZS

New Member
Got the bug to look at the Marantz SR-2000 I received in a lot of stuff from an Estate purchase. Very nice shape, no wooden cabinet, lamps out (already have the LED replacement kit)

I suspect that the STK080G power modules are bad as the sound output is low and poor quality. (Can't compare to my 2245 which I've owned since new, but this receiver has a problem)

Lots of potentially bogus parts on ePay, from China ... but I do see a pair available from Cicon Electronics in NY state.

https://www.ciconelectronics.com/stk080g.html

$20 each compared to $7 from Cheena, but I wonder if anybody has experience with Cicon. Anybody come up with an acceptable replacement set (the 082 or?)

Also, anybody know where a Service Manual download might be (without paying $20 for that too?)

I know automatically replacing the power modules without a little digging is probably not the perfect troubleshooting technique, but these have a history and while I can find the parts, and my zero dollar investment, it couldn't hurt.

No recent threads on this 1980 machine ... any thoughts?

Thanks - Kevin K7ZS
 
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Kevin K7ZS said:
Also, anybody know where a Service Manual download might be (without paying $20 for that too?)
Click to expand...
SR-2000 SM here: https://www.hifiengine.com/manual_library/marantz/sr2000.shtml

The first thing to try is clean the volume control and switches with Deoxit (or other cleaner) to make sure there is no oxidation causing output signal issues.
Next is to check the voltages at the Power Supply output and voltage to the amplifier modules. See schematic.

upload_2022-6-30_10-11-1.png
 
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Hi dankik

I did find a (medium quality) scan, thanks for the nice P/S Scan. I do have both D5 and F5 (Fader Lube) cleaners, so I will do the basics first. Thanks for reminding me of proper troubleshooting techniques! Do the basics first.

Thanks and stay tuned!

-Kevin
 
Do you need the manual? I have the one from hifiengine.
One other thought... have you tried listening using headphones to see if there is a difference?
 
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Hi Dankik

I took the cover off today, and lo and behold, one of the power modules had already been replaced, with an NTE1327 which I haven't checked to see if it's a suitable replacement ...

But ...

In the meantime, I used F5 Fader Lube on all of the control pots. I made a mistake by not listening on headphones BEFORE the fader lube, but without having speakers handy I threw some low quality (tablet) audio into the TAPE2/AUX port, and on headphones it sounds clean! (Of course no match for a 2245 ;)) I will try into speakers this afternoon, but the low output and muddy sound of my first trial into speakers (6 months ago) seems to have improved. I will put on speake rs after lunch and see how it goes.

All else is working, I replaced he meter and dial indicator lamps with LED modules, and she looks OK now after cleaning knobs (Of course no match for a 2245 ;))

First blush issues:
FM reception seems poor (300 ohm twin lead antenna) and AM reception with internal bar antenna very thin? I am 20 miles from the towers here in the Portland Oregon west side, but they are line of sight.

Also, tone controls appear fine with the exception of the treble adjustment seems very minimal to non-working? (or my upper range hearing is long gone ... I but I think I should hear a more pronounced difference).

I did download a service manual, readable enough - and if I expand each board and 'screen capture' from it I have a acceptable printable copy to check voltages.

To be continues, but feels like some progress. I'll be checking the NTE part to see if it's a proper sub, but I can't tell much difference from LEFT and RIGHT channels, so maybe it is?

If I run into a SM unreadable page etc. I may ask for that, thanks for the offer.

THANK YOU!

-Kevin
 
Kevin K7ZS said:
with the exception of the treble adjustment seems very minimal to non-working?
Click to expand...
upload_2022-6-30_16-25-52.png

The Treble control is purely passive and in series with the Mid and Bass controls. Maybe your ears are like mine, not what they used to be.
 
Well, CAIG DeOxit ... once again ... has come through! Hooked up the SR-2000 to some Pioneer speakers in the shop, and damned if it didn't sound very good. Had one brief dropout of the left channel, but a little DeOxit D5 on the speaker switches took care of that, and played at decent volume levels for 30 minutes without incident. The treble control also had a bit more pronounced effect on the tone, so I think partly the headphones (not Audio headphones) plus 69 year old ears are largely to blame. Game the SR-2000 to a neighbor to play with, with a pair of Bose AM-5's so he's enjoying it. I still need to service / check the radio section ... STEREO light only flickers after passing the 'zero beat' with the FM stations, but for now my friend gets to play his recorded material on a much nicer receiver than he had. So, a good day. THANKS and when I start working on the FM section in particular, I'll probably be back!

Thank you AGAIN AudioKarma and Dankik!

-Kevin
 
Yes, my neighbor is enjoying it, the FM is working fine at his place. Maybe it's time to install the LED and new Vellum in my 2245. I redid original bulbs about 5 years ago, but have the LED's here... I did a 2010 for my friend and after I figured out to do Double Vellum to get rid of the 'hot spots' it came out crisp and even.

SO rewarding to keep these classics alive! I have done primarily Ham Radio work on Kenwood, Collins and Drake gear made the late 60's through early 80's until they started becoming black boxes. Same satisfaction! Keeping these radios from that dreaded Ill Fate!

'73' in HamSpeak -Kevin
 
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