View Full Version : Inside the JC Penney MCS 3050 Tuner


uxwbill
12-19-2010, 03:14 AM
Someone asked me if I could get pictures of the JC Penney MCS 3050 tuner's internals. The MCS 3050 is your average AM/FM tuner, with the added bonus of a built in Motorola C-QuAM decoder (an MC13020) to play back any AM stereo broadcasts if you can still find any in your part of the world. There are a few on my end, and I'm a big proponent of quality analog AM broadcasting. Done right, AM radio can sound quite good!

My example is still in excellent working condition.

Here come the pictures, along with some explanatory text. Each picture can, generally, be clicked to see a high resolution version. The high resolution pictures are LARGE and those who may be in a limited bandwidth situation or using an older computer are suggested not to view them!

http://greyghost.mooo.com/mcs3050/3050smallfront.jpg (http://greyghost.mooo.com/mcs3050/3050bigfront.jpg)

There's the front of the unit with the cover off, ready for examination on my state of the art Electronics Examination Table (sometimes called a "bed"). Note that the front panel is NOT plastic. It's made of metal!

http://greyghost.mooo.com/mcs3050/3050smalltuning.jpg (http://greyghost.mooo.com/mcs3050/3050bigtuning.jpg)

This is the tuning and audio board. It contains a few power components, notably the filter capacitors and a regulation transistor (screwed to the heatsink). Also note that each major functional circuit is outlined and labeled.

http://greyghost.mooo.com/mcs3050/3050mcuboard-small.jpg (http://greyghost.mooo.com/mcs3050/3050mcuboard-big.jpg)

And there's the MCU board. The separation is interesting and suggests that someone cared about building a high quality tuner. Somewhere I had the datasheet for that NEC uPD1704C chip, but I can't find it now. It's a 4-bit microcontroller. Note the rather large capacitors, probably used to keep its memory intact when power is not connected to the unit.

http://greyghost.mooo.com/mcs3050/3050mcuboard-numbers.jpg

These are the numbers printed on the MCU board. I thought it said "TEC", but it clearly does not. This board is identified as PWA-1704 / 72917042-2 .

Here are the numbers from the tuning/audio board:

http://greyghost.mooo.com/mcs3050/tuningboardnumbers.jpg

This board is also marked as "PWA-1704" but the other number has changed: 72917042-1 .

AM tuning is done by a Sanyo LA1247 (intended for and designed with AM stereo capable tuning in mind, and having an improved signal-to-noise ratio as compared to the LA1245).

FM tuning is handled by a Hitachi HA11225 FM IF IC and an NEC uPC1235C stereo detector (for which I could not find a datasheet).

Datecodes on the components all suggest a build in early/mid 1985. On the back there is a datecode of "506", which suggests the sixth month of 1985. (I assume that the code on the back must be given in months, as several ICs have year/week (or week/year) datecodes that would not be possible if the rear datecode were also expressed in weeks.

On the back...mine is serial #4561407, model #683-3050, catalog # 853-6641. Power source is listed as AC 120 V (only, no other taps are present on the transformer, nor is there a voltage selector), for use with 60Hz power. It is said to consume 12 watts while operating.

The UL file number is E55522, listing number 154L, and the product service number--which I assume could have been used to order a service manual back in the day--is 683-3050-00. This was made in Japan.

Speaking of the service manual...might anyone have it? I want to find a copy and would gladly pay for shipping. If need be, I can scan it and return it to you. I do not believe that StereoManuals.com has it, but I have yet to ask and be absolutely certain.

Also: anyone want to tell me how many filters or "gangs" (or their electronic equivalent in this case) this thing appears to have? I'll confess that I don't know about the gangs, and I don't see any obvious filters in the circuit.

Perhaps nobody asked, perhaps nobody cares, but I have a golden screwdriver and an open evening. So...

"Now you know."

Hifirob2
12-19-2010, 01:41 PM
Very interesting - and detailed look inside! I see some resemblance to my NEC T-610, and some to my NEC T-6 - along with the tuner sections of my MCS 3260, 3265, and 3285 receivers.

The HA11225 chip is also used in the 3265 and 3285, and I believe in the 3260 as well.

I see only 2 FM "gangs", but I could easily be wrong. I do see two ceramic filters for the FM, and CF601 looks like a higher quality ceramic filter in the AM section.

The board codes are all similar to all of my NEC pieces, but my only one that is sectioned off by names is in the 3265 receiver. My Technics tuners usually had section marks and names on the boards, but with a different font. So my money says NEC built this tuner. You are right with the date code being June, 1985.

The service manual may be hard to track down, even an owners manual. As for specs on the 3050, I have these:

Frequency response of 20 - 15k Hz +/-3dB
Usable sensitivity of 2.0uv
capture ratio 1.2dB
Image rejection 45dB
Stereo separation (FM) 45dB
Quieting sensitivity 5.0uv
Mono THD 0.2%
Stereo THD 0.3%
AM sensitivity 300uv
AM selectivity 23dB
Signal to Noise ratio (FM) 45dB

I think I read over on the Tuner Information Site that they liked the AM stereo performance, but weren't too impressed with the FM sound quality.

Very nice to see the insides! Thanks. :thmbsp:

EddyFranner
12-19-2010, 01:46 PM
I found that MCS made some good gear, interesting break down and photos.

Vintage_Hi-F
12-19-2010, 02:17 PM
I found that MCS made some good gear, interesting break down and photos.

you mean had some good gear made for them. They never made a thing, just like Tandy.

EddyFranner
12-19-2010, 03:31 PM
MCS was a house brand for JC Penny's, who manufactured the stuff?

Hifirob2
12-19-2010, 03:41 PM
MCS was a house brand for JC Penny's, who manufactured the stuff?

Usually it went to the lowest bidder among the big Japanese companies, I think. NEC, Technics, and a few others.

Some items were simply re-badged models, and some were unique, built to spec pieces to compete at a price point.

Quality varied as with most brands, but some pieces were real gems.

Curtis Mathes went the same route for their audio components, using re-badged NEC and Technics for many pieces. If you know what to look for, you can get some good deals on the "unknowns". :yes:

mikeberry
12-19-2010, 09:01 PM
Speaking of MCS, I have an interesting MCS VTR component TV. Model # 685-1015. I think its pretty cool. :D My parents are the original owners.

Hifirob2
12-19-2010, 09:09 PM
Speaking of MCS, I have an interesting MCS VTR component TV. Model # 685-1015. I think its pretty cool. :D My parents are the original owners.


Those are pretty cool. I like that it has four different ranges for the power output. It probably puts on a good show. :thmbsp:

mikeberry
12-19-2010, 09:36 PM
Those are pretty cool. I like that it has four different ranges for the power output. It probably puts on a good show. :thmbsp:

It does, and I can even watch B/W TV; what more could you want? :lmao:

EddyFranner
12-20-2010, 12:43 AM
:thmbsp:Usually it went to the lowest bidder among the big Japanese companies, I think. NEC, Technics, and a few others.

Some items were simply re-badged models, and some were unique, built to spec pieces to compete at a price point.

Quality varied as with most brands, but some pieces were real gems.

Curtis Mathes went the same route for their audio components, using re-badged NEC and Technics for many pieces. If you know what to look for, you can get some good deals on the "unknowns". :yes:

uxwbill
12-20-2010, 01:08 AM
They never made a thing, just like Tandy.
Actually, Tandy (or RadioShack, or whatever you want to call them) claimed that they did have a few manufacturing plants of their own, where they did make some things by themselves. I can't prove it, but I doubt that they were totally making it up, either.

And there was the Tandy Wire and Cable division, which as far as I know, was indeed capable of manufacturing (mostly) coaxial cables.

SixCats!
06-29-2012, 07:29 PM
Hello All,

UXW, nice thread and pictures. I found this old thread searching Google. Today, I just happened to find a VERY GOOD condition MCS 3050 Tuner at the Thrift Shop for six dollars. Heck, it's a nice sounding Tuner, especially for six bucks. I connected the 3050 it to a circa 60's Realistic SAF-40B (7189) Integrated Tube Amp(twenty watts per channel) connected to a 60's pair of Wharfedale W90's. Presently, I'm listening to 102.9 WBLM (Portland Maine). Beatles, Aero Smith, Metallica etc. coming in strong and clear. I live forty five miles North of Portland. It would appear everything is working on this circa 1980's Tuner. I wonder who made it for J.C. Penny ?

Regards,
SixCats!

Hifirob2
06-29-2012, 08:08 PM
Hello All,

I wonder who made it for J.C. Penny ?

Regards,
SixCats!

NEC made the 3050 for JCPenney.