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 Post subject: Marantz SR 4000 Receiver
PostPosted: Feb Sun 02, 2020 8:59 pm 
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Joined: Jan Sun 11, 2009 8:39 pm
Posts: 22
Location: Newmarket Ontario Canada
My neighbor gave me this receiver to try and fix as his friend who is a tech guy gave up on it.. It will not power up. I hooked it up to my dim bulb tester and the bulb lit up like a Christmas tree but the receiver would not come on.. I opened it and checked the transformer and it is putting out ac, the fuses have not blown. I disconnected the B+ line and got about 60 volts with the dim bulb tester flaring up and then going out. This unit uses those Hybrid amp modules along with another Hybrid module as a driver I believe. The amp modules are STK 0050 II good for 50 watts or so.
It would appear that one or both modules are shot but I am not sure how to test them.. Should they be removed or left in without powering up the receiver ?

From searching around I have found there is not a lot of love for these particular amp modules and most replacements are Chinese fakes that do not last at all. If anyone has any experience or tips on checking the unit out, it would be appreciated,, I have downloaded the service manual from HiFi Engine to help out. I have not had any experience with these hybrids and prefer discrete components that you can test and replace with substitutes.

Thanks for your time Cheers Wayne


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 Post subject: Re: Marantz SR 4000 Receiver
PostPosted: Feb Sun 02, 2020 9:08 pm 
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Location: NJ 08090
I learned for the most part...If someone's been in it (the tech guy) before and it's still in-op, probably not worth the effort. Especially with the modules. Good chance the previous tech may have messed up some stuff too. Have at it...but I'd probably let it go...just my $0.02.


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 Post subject: Re: Marantz SR 4000 Receiver
PostPosted: Feb Sun 02, 2020 9:21 pm 
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Location: Newmarket Ontario Canada
Thanks Tbirdkid.. I will see what I can do and then let it sail off into the recycle bin Cheers


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 Post subject: Re: Marantz SR 4000 Receiver
PostPosted: Feb Mon 03, 2020 5:12 am 
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i had an SR 6000 DC at one point in my life.

it was a bit cheesier than the 'normal' older Marantz amplifiers, but it really did do a great job. it sounded wonderful and i believe it had 80 watt chips in it.

i liked it.

steve

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 Post subject: Re: Marantz SR 4000 Receiver
PostPosted: Feb Mon 03, 2020 5:31 am 
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If you don't hear the speaker relay click within a few seconds of powering up, most likely one or both of the STK modules are shorted. Then it becomes a parts unit.

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 Post subject: Re: Marantz SR 4000 Receiver
PostPosted: Feb Mon 03, 2020 5:35 am 
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absolutely agreed

steve

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 Post subject: Re: Marantz SR 4000 Receiver
PostPosted: Feb Sun 23, 2020 9:03 pm 
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Location: Newmarket Ontario Canada
The receiver is up and running after replacing both amp modules as well as the voltage amplifier modules.. Dial lights were out so I replaced them and you were right someone played around with the ac lines so the level meters did not work.. The pin on the underside of the circuit board was not connected to the foil, it was broken off so I relocated the pin further along, drilled a new hole and resoldered the pin to the foil line.

Now doing a clean up and letting it cook, so far the modules only reach a temp of 25C when driving my AR3A's for 48 hours at normal volume.. Tried them a lot louder , I do not have a dummy load , and the temp rose only 2 C to 27C.

Not sure I want to tackle another one like this but it does sound pretty good overall. No noise , hiss or hum and the DC offset is 0 mv both channels.. AC ripple is 20 mv both channels

I really do not want it as I have a Heathkit AR1500 so it is going up for sale once I am satisfied with it, Thanks for all the input and this was learning experience for me.. Cheers


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 Post subject: Re: Marantz SR 4000 Receiver
PostPosted: Feb Sun 23, 2020 10:13 pm 
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where did you find the amp modules ?
steve

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 Post subject: Re: Marantz SR 4000 Receiver
PostPosted: Feb Mon 24, 2020 2:40 pm 
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Dutch Rabbit wrote:
where did you find the amp modules ?
steve

Steve, I was wondering the same! I have not worked on any of the receivers that use modules. But I get the idea that there are a lot of counterfeit modules out there.

Just wondern'.

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 Post subject: Re: Marantz SR 4000 Receiver
PostPosted: Feb Mon 24, 2020 3:18 pm 
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Location: Norfolk, VA
I've got several NOS STK0050 from Technics (we were a Panasonic/Technics warranty station for a while), and just last October helped Terry R (on another forum) verify that the GE Modules he was buying were the cross for the STK0050. They aren't hens' teeth yet....

If you can't find true NOS, GE, SK and ECG are viable options - they are simply remarked STK modules. The newer NTE could be, or could be a Chinese counterfeit, so I never attempt to use them. ECG, GE, and SK all got out of the replacement semiconductor business before the flood of Chinese fakes. Another option is RCA OEM - when Thomson dropped the SK line, they took many STK's destined to become SK devices and assigned them a series of OEM RCA part numbers.

http://talonelectronics.com/shop/catego ... ?catid=324

Scroll down the page until you see the RCA packages and you'll see what I'm referring to.

You can also sometimes go "up" in a series to the next, more powerful device. You won't get anymore power, but it will work as advertised. "STK43X" series being the prime example - the 435/437/439 are up-devices, that is you can use the higher number to replace the lower part numbered devices. Same for some of the STK2000 and STK 4000 series - you just have to verify the pinouts on the devices. I've got a Sanyo guide from somewhere around 1999 that explains this - referring to "maintenance types" that can be replaced by "production types" - all simply higher numbered devices that will work in 99% of applications.

None of the up-device stuff works with the STK regulator, pin-driver, motor driver, or convergence amp STK hybrid modules. :cry:

I'd rather be on the hunt for an STK device than an obsolete TO-3 power device. I've grown weary of trying to find high voltage, high current TO-3 outputs for Asian made servo boards. Thankfully, they (NEC, Hitachi, Toshiba and others) went power MOSFET at the earliest opportunity..... 8)

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 Post subject: Re: Marantz SR 4000 Receiver
PostPosted: Feb Tue 25, 2020 3:20 pm 
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Location: Newmarket Ontario Canada
Steve and Don, I purchased the voltage and amp modules from an Electronics Supplier here in Ontario called Consumer Parts Source. It appears to be numbered Company that sells direct and also on EBay.. They had a very good rating and I did not want to order from China so I went with them.. The STK 3062 III module was used to replace the STK 3062 and I only reused the small caps that were on the original module. I am aware now that the data sheet for this version shows a resistor and another small cap added, no doubt to eliminate oscillations. So far I have had no issues, but then I do not have a scope to check this.

I plan on hanging on to the unit for a while to see if all the parts hold, but at this point they seem fine. I ordered an extra STK 3062 III just in case it caused an issue.

I do not know if the Company ships to the US but the link is consumers-parts.com. Hope this is helpful

Cheers Wayne


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 Post subject: Re: Marantz SR 4000 Receiver
PostPosted: Feb Tue 25, 2020 4:21 pm 
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i always liked the sound of stk chips.

steve

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 Post subject: Re: Marantz SR 4000 Receiver
PostPosted: Feb Tue 25, 2020 5:17 pm 
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Kingboy wrote:
Steve and Don, ...
I plan on hanging on to the unit for a while to see if all the parts hold, but at this point they seem fine. I ordered an extra STK 3062 III just in case it caused an issue....
Cheers Wayne

Good to hear, Wayne. Glad that you were successful. Thanks for taking the time to respond.

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 Post subject: Re: Marantz SR 4000 Receiver
PostPosted: Feb Thu 27, 2020 12:23 am 
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Dutch Rabbit wrote:
i always liked the sound of stk chips.
steve
The STK devices were very well designed. They were extremely linear and they were free of “crossover notch distortion.” Numerous “mid-power” (30 to 50 watts/channel) stereo receivers contained STK modules from 1972-1980.

-EB

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 Post subject: Re: Marantz SR 4000 Receiver
PostPosted: Feb Thu 27, 2020 1:42 am 
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i have a vintage onkyo that has STK 50 III or 80 III chips.

it sounds wonderful and has some very conservative power.

steve

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 Post subject: Re: Marantz SR 4000 Receiver
PostPosted: Feb Thu 27, 2020 6:21 pm 
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Dutch Rabbit wrote:
i have a vintage onkyo that has STK 50 III or 80 III chips.
it sounds wonderful and has some very conservative power.
steve
IMHO, Onkyo made superb sounding but moderately priced stereo gear during the 1970’s. Actually they still make high-quality audio and home-theatre gear today.

Some of my favorite Onkyo models:

Their drop-dead gorgeous all-metal silver-face separates from the 1970’s:
    A5, A7, and A10 integrated amplifiers
    T-4 and T-9 AM/FM tuners

All of their receivers with analog tuning. Especially the TX-2500 and TX-4500. These also came in a “series II” version which was equally good if not better.

TA-2050 cassette deck. Same tape transport mechanism as Nakamichi and H-K.

-EB

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 Post subject: Re: Marantz SR 4000 Receiver
PostPosted: Feb Thu 27, 2020 9:17 pm 
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mine is a TX-3000.

it is very conservatively rated...very.

viewtopic.php?t=367754

the chips are 50 III for the output, not 80.

i absolutely LOVE the sound.

the lighting of mine is on page 2 of this thread.

viewtopic.php?f=13&t=366505&hilit=+LED

steve

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 Post subject: Re: Marantz SR 4000 Receiver
PostPosted: Feb Thu 27, 2020 9:52 pm 
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Dutch Rabbit wrote:
mine is a TX-3000.
The lighting of mine is on page 2 of this thread: http://antiqueradios.com/forums/viewtopic.php?f=13&t=366505&hilit=+LED
steve
I'm ordering a bunch of these today:

http://www.parts-express.com/warm-white-3-led-axial-8-vdc-replacement-lamp-5-pack--070-144

These strips with SMT LEDs and lead wires on the ends will work perfectly in a whole bunch of different applications where the original incandescent lamp was a "fuse lamp" or a tubular lamp with wire leads. And they are available in both "warm white" and "green" which are my two favorite colors for re-lamping vintage electronics.

-EB

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 Post subject: Re: Marantz SR 4000 Receiver
PostPosted: Feb Thu 27, 2020 10:09 pm 
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electricboyo wrote:
Dutch Rabbit wrote:
mine is a TX-3000.
The lighting of mine is on page 2 of this thread: http://antiqueradios.com/forums/viewtopic.php?f=13&t=366505&hilit=+LED
steve
I'm ordering a bunch of these today:

http://www.parts-express.com/warm-white-3-led-axial-8-vdc-replacement-lamp-5-pack--070-144

These strips with SMT LEDs and lead wires on the ends will work perfectly in a whole bunch of different applications where the original incandescent lamp was a "fuse lamp" or a tubular lamp with wire leads. And they are available in both "warm white" and "green" which are my two favorite colors for re-lamping vintage electronics.

-EB


those are exactly what i bought (warm white). i bought a few packs as well as they can be very versatile.

what i did on mine, i took a "whatever ohm" (can't remember) 1/2 watt resistor inline and heat shrinked on the power bus wire to the panel lamps. it brought the voltage down so they only see 5.x volts instead of 7-8 v.

the brightness difference was minimal as it also added that nice "glowing" ambiance to the dial.

steve

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 Post subject: Re: Marantz SR 4000 Receiver
PostPosted: Mar Mon 02, 2020 2:01 pm 
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yesterday, i was given an LXI amplifier. it has STK 100 "Darlington" chips.

it is probably one of the last chip amps b/c it is black and looks to be very late 80s.

it certainly isn't like the high end items i have, but it sounds good for what it is, and has that nice warm robust STK sound to it.

there is something about mosfet transistors and darlington STK chips that my ears just like.

steve

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