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 Post subject: Home-Mark stereo console
PostPosted: Jun Tue 04, 2019 3:03 am 
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Joined: Dec Sun 21, 2014 5:03 am
Posts: 278
Location: Traverse City, MI 49684
I found a low-end console sitting at curbside a couple weeks ago just before a thunderstorm was going to hit and it followed me home. It's labelled "Home-Mark" and has a model 336 number on it. The cabinet was nearly perfect, with unusually nice veneers for a cheapie, and everything except the grille cloth and speakers was in good physical shape. The cloth was all gone as were the cones of the speakers. At first plug-in, the FM stereo light came on but I had no sound because of no speakers. Later, when I plugged some small speakers into the speaker-out jack, nothing lighted up.

It seems to have series-string tube heaters (two 50C5s and 6 12-volt tubes) but there is also a two-tube multiplex device that's separate but with no visible power supply (two 6-volt tubes). There's a larger transformer on the bottom of the unit where the tiny output transformers are. That's at least for B+, I figure, and maybe it has a 6-volt tap for the MPX device.

The console is identical to this one, a Madison-Fielding, and mine has two M-F branded tubes:
https://www.ebay.com/itm/Madison-Fieldi ... 2920913575

Mine also has the MPX device that the pictured one lacks. That one is called a "360" in the ad but Madison-Fielding made some much higher-end separates and one of the amps is a 360.

That's a long way to asking if anybody has leads on a schematic for either the Madison-Fielding or Home-Mark brands.

Thank you,
Chris Campbell


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 Post subject: Re: Home-Mark stereo console
PostPosted: Jun Tue 04, 2019 3:26 pm 
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Joined: Jan Wed 16, 2013 12:04 am
Posts: 1531
Location: 77001
Hi Chris,

I found an M-F "360" series found in Sams,
but it is as you said a high-end amp from M-F.

None of the M-F listings in Sams is a low end product.

Hotwax


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 Post subject: Re: Home-Mark stereo console
PostPosted: Jun Wed 05, 2019 12:19 am 
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Joined: Dec Sun 21, 2014 5:03 am
Posts: 278
Location: Traverse City, MI 49684
I'm a bit surprised that a company that made and sold higher-end stuff was also selling low-end consoles like this one. It has 6" woofers, 4" tweeters, and a single-ended 50C5 amp with tiny output transformers. But the one in the eBay ad I linked was M-F branded and a couple of the tubes in mine bear that label also. It's sort of like H.H. Scott or Marantz selling a suitcase portable with a crystal cartridge. My best guess is that somebody bought the name and upgraded or downgraded the product depending on sequence. The only problem with that hypothesis is that the little console and the high-end components appear to have been produced at about the same time.

Maybe when I pull the chassis it will have some more identifying info.

Low-end or not, I'm always a sucker for old electronics, especially when they're about to get rained on or crushed by the garbage truck.

Chris Campbell


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 Post subject: Re: Home-Mark stereo console
PostPosted: Jun Wed 12, 2019 3:32 am 
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Joined: Dec Sun 21, 2014 5:03 am
Posts: 278
Location: Traverse City, MI 49684
Let's try again. My first reply disappeared when I hit "submit."

The little console lives in the town where I grew up, not where I live, so I visit it on weekends. This past weekend's project was to pull the chassis to figure out why the series-string filaments weren't lighting up when the tubes all tested OK. In the process of removing the chassis, I dropped it and broke off the FM antenna twinlead. $^&*#@!!! Luckily, that was easy to re-solder. Then I put an ohmmeter on the on-off switch, a DPST slide switch on the volume control shaft. Hmm, no continuity. I had no cleaner but a couple bursts of WD-40 cleaned it up and it tested as OK. AM worked, FM worked, FM stereo worked, and the record changer passed the "needle-scratch" test. The motor won't go yet.

Getting the chassis back in is a two person job. When back in, I hooked up two external speakers, turned it on, and bingo! The stereo light came on and soon enough I had sound. It was grainy or hummy and without much gain for a while, but the modern-looking filter caps seem to have reformed after it played a while. Now I have ordered some upgrade speakers--rubber-surround nes from Parts Express, cheaper at $5.99 each than the OEM Quams on eBay and probably better sounding.

Chris Campbell


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 Post subject: Re: Home-Mark stereo console
PostPosted: Jun Wed 12, 2019 4:03 am 
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Joined: Feb Wed 04, 2015 12:26 am
Posts: 906
First, if is this a low power tube unit. DO NOT replace the speakers, you will not be happy at all with the results. Speakers for tube amplifiers are matched for the power of the amp, and the enclosure/cabinet they sit in. They all work together as a cohesive unit.

Also, this system must be completely rebuilt electronically. Especially if this has a power transformer. If a series of certain parts goes out, it can cause a cascade failure , taking parts out that are not replaceable at the least, or start a house fire at the very most. It can happen very fast. It noted that this is series string unit, all caps still must be replaced.

The changer will need to be cleaned and relubed to restore full operation.


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 Post subject: Re: Home-Mark stereo console
PostPosted: Jun Wed 12, 2019 4:59 am 
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Joined: Aug Tue 24, 2010 8:56 pm
Posts: 5661
Location: Northeast Florida
I find it odd that this unit uses a crystal cartridge, considering it has a preamplifier stage.

I've seen one lower-end console than that, and it was built by Arvin. Phono-only, 3 tube ac/dc amp, and a 6" speaker for each channel with no tweeters

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William


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 Post subject: Re: Home-Mark stereo console
PostPosted: Jun Wed 12, 2019 11:34 pm 
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Joined: Dec Sun 21, 2014 5:03 am
Posts: 278
Location: Traverse City, MI 49684
Thanks for all the comments. Here are some replies.

First of all, it's likely a ceramic cartridge, given its age (after early 1961, at least, because it has a factory-installed multiplex unit added on). There's no dedicated preamp, as far as I can see, although I don't have a schematic for the device. Ceramics were common with the V-M 1200-series changers of the era.

I'd love to see a schematic but all efforts to locate one have failed. A search under the Madison-Fielding model number of an identical unit sold under the M-F name on eBay just turns up the high-end M-F amp using the same model no.

Also, the only power transformer may be for the MPX unit, although I can't tell for sure. The filaments are series-string, at least on the main chassis, although I think the added-on transformer may supply the 6V for the two MPX tubes. I didn't try to figure out the circuit when I had the chassis partway out because I was in a dark garage, struggling with maneuvering the chassis that doesn't easily disconnect.

I know that it's risky to power-up an old device, but this one has modern-style, plastic covered filter caps, and if the transformer does supply B+ to all the tubes, it's a small and likely inexpensive device. I just figured that the risk was small.

As to the speakers, they were gone. As found, the device had no grille cloth and the cones of all 4 speakers had been ripped out. Voice coils & spiders intact, but the wires to voice coils were broken. Similar Quam 6" speakers on eBay were half-again more expensive than the 6-1/2" 4 ohm speakers that Parts Express had. I already had some inexpensive tweeters from PE that I'll try. I'm not sure that a lot of listening tests went into filling this little console with speakers, and if the Parts Express models sound dismal, I can always revert to Quams. But those look like AA5 table-radio speakers, so I'm not sure that they would be an improvement. We'll see.

On the plus side, this is an attractive little console in very good physical condition. The design is simple, the veneers are real and good-looking, and it wasn't banged up. Everything was there. I saved it from the crusher. And with a bit of prompting, it worked! If it sounds better than expected, or if I find a location where I can use it as a daily driver on FM, maybe I'll worry about cap replacements. Right now, I'm just getting started.

Chris Campbell


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 Post subject: Re: Home-Mark stereo console
PostPosted: Jun Wed 12, 2019 11:39 pm 
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Joined: Jan Wed 16, 2013 12:04 am
Posts: 1531
Location: 77001
Thanks Chris for saving another hi-fi !
Hotwax


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 Post subject: Re: Home-Mark stereo console
PostPosted: Jun Wed 12, 2019 11:47 pm 
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Joined: Dec Sun 21, 2014 5:03 am
Posts: 278
Location: Traverse City, MI 49684
Hotwax wrote:
Thanks Chris for saving another hi-fi !
Hotwax


I never pass a forlorn electronic orphan. Another person observed that the magic words are "old and free." And this one was just too good looking to leave there with a rain storm approaching.

Chris Campbell


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 Post subject: Re: Home-Mark stereo console
PostPosted: Jun Sun 16, 2019 3:23 am 
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Joined: Dec Sun 21, 2014 5:03 am
Posts: 278
Location: Traverse City, MI 49684
The little console got its $5.99 6-1/2" woofers and some tweeters, also from Parts Express, price forgotten, today. The tweet needed plywood adapter rings--smaller than originals--but the new woofer fit exactly on the existing studs. I used push-on connectors so the chassis can be removed.

Sound is surprisingly good, nice bass and high, but it's a bit weak on gain. Not sure about that... maybe weak B+? But there's no notable distortion--sounds pleasant and well-balanced, so any component issues aren't affecting sound quality, just quantity. Maybe I'm just expecting too much noise.

Chris Campbell


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 Post subject: Re: Home-Mark stereo console
PostPosted: Jun Sun 16, 2019 3:04 pm 
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Joined: Jan Wed 16, 2013 12:04 am
Posts: 1531
Location: 77001
Good job, Chris.

How about a photo or two ? [ : )

Can you also show me what kind of
push on connectors you used ?

Hotwax


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 Post subject: Re: Home-Mark stereo console
PostPosted: Jun Sun 16, 2019 3:46 pm 
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Joined: Dec Sun 21, 2014 5:03 am
Posts: 278
Location: Traverse City, MI 49684
I've got some photos and will try to post next week when I'm at home and can go through the whole re-sizing exercise. I'll also post a short YouTube video I made. The connectors were the standard crimp-on flat devices from the hardware store. They weren't a perfect fit for the speaker lugs but were close enough. The old speakers were soldered in, which made it impossible to extract the chassis very far.

I was out listening to the unit last night to see what the AM performance was like at night--not spectacular is the answer. I did notice a bit of hum on FM. The filter caps probably do need replacing. When I had the chassis out as far as it would go last weekend I couldn't quite see the filter cap markings. I still hope for finding a schematic, maybe under the Madison-Fielding name.

But the good news is that it works, the new speakers sound quite good, and the phono cartridge is intact. Oh yeah, and that the garbage crusher did not eat the whole thing a few weeks ago when I spied it.

Chris Campbell


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 Post subject: Re: Home-Mark stereo console
PostPosted: Jun Sun 16, 2019 3:54 pm 
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Joined: Dec Sun 21, 2014 5:03 am
Posts: 278
Location: Traverse City, MI 49684
I just went out to the garage and checked the push-on connectors. They're from Ace Hardware although they're a standard size. The older label says "Terminal--insulated" and "disconnect." The newer box says "Female disconnect." These are for 22-16 AWG wires. The Ace part no. for both new and old packaging is 34519. A narrower connector (the tweeter had one wide and one narrow lug) bears part no. 3015393. They just slide on.

Chris Campbell


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 Post subject: Re: Home-Mark stereo console
PostPosted: Jun Sun 16, 2019 4:03 pm 
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Joined: Dec Sun 21, 2014 5:03 am
Posts: 278
Location: Traverse City, MI 49684
The woofers I used:
https://www.parts-express.com/6-1-2-pol ... m--299-609

The tweeters:
https://www.parts-express.com/t-25-2-1- ... m--279-452

I used the existing .5 mfd. high-pass cap to the tweeter because that's all I had on hand.

Chris Campbell


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 Post subject: Re: Home-Mark stereo console
PostPosted: Jun Sun 16, 2019 6:24 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 2649
Location: Haledon NJ USA
The reason for the lack of volume may be that you're using woofers with a soft edged cone. These will not work properly in a cabinet with a vented back. See the note on the page where you purchased them: "Designed for use in sealed cabinets".

Looking forward to your video.


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 Post subject: Re: Home-Mark stereo console
PostPosted: Jun Mon 17, 2019 5:01 am 
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Joined: Dec Sun 21, 2014 5:03 am
Posts: 278
Location: Traverse City, MI 49684
The good news is that they're louder than the Radio Shack systems that I used for initial testing. And I was worried that the speakers would be over-compliant without the air cushion behind them, but at least in terms of tonal balance, they are surprisingly good. The voice coils don't bottom out on the magnet structure--an ugly noise if there ever was one. The original speakers were what you'd find in an AA5 radio, and I didn't expect that the console would sound very good with them. To find out it would have cost me $16 (eBay) vs. the $12 I paid for these. It seemed like a reasonable gamble.

I do think there's some electronic explanation. The AM section is quite insensitive, especially at the lower-frequency end, and the FM section is not greatly better (although that's with the internal dipole, the standard two-wires-stapled-to-cabinet). Maybe next week I'll take along a folded dipole on a stick and see what that does for FM. I'll also take a look at the AM ferrite bar antenna and make sure that none of the wires were damaged when I was struggling to get the chassis back in.

Chris Campbell


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 Post subject: Re: Home-Mark stereo console
PostPosted: Jun Mon 17, 2019 5:21 am 
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Joined: Aug Tue 24, 2010 8:56 pm
Posts: 5661
Location: Northeast Florida
For the AM section--tune to a station around 1400 and adjust the antenna trimmer on the tuning condenser. I'd estimate that 75% of the radios I work on benefit from it

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William


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 Post subject: Re: Home-Mark stereo console
PostPosted: Jun Tue 18, 2019 3:15 am 
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Joined: Dec Sun 21, 2014 5:03 am
Posts: 278
Location: Traverse City, MI 49684
tubes4life wrote:
For the AM section--tune to a station around 1400 and adjust the antenna trimmer on the tuning condenser. I'd estimate that 75% of the radios I work on benefit from it


I don't have a schematic--any quick way to tell from the outsidewhich is oscillator and which is RF?

Chris Campbell


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 Post subject: Re: Home-Mark stereo console
PostPosted: Jun Tue 18, 2019 3:19 am 
Member

Joined: Dec Sun 21, 2014 5:03 am
Posts: 278
Location: Traverse City, MI 49684
I just made a very short (1 min. 40 sec.) YouTube video of the little console playing. In the very first seconds you can get a glimpse of the baskets of the old speakers on the floor behind. The previous owner had ripped the cones out and the grille cloth off. ???. I have some still of the new speakers outside the console, but first I'l have to take a deep breath and submit to the "resizing" process (a daunting thing because I have to relearn each time). I'm amazed at how good this little flea-powered device sounds through its puny output transformers.

Here's the link:
https://youtu.be/d7vQtXntV9A

Chris Campbell


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 Post subject: Re: Home-Mark stereo console
PostPosted: Jun Thu 20, 2019 3:20 am 
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Joined: Dec Sun 21, 2014 5:03 am
Posts: 278
Location: Traverse City, MI 49684
Let's see if I can add photos after resizing (a great struggle). I'll show two views of the new speakers (tweeter has plywood adapter ring for fit) and one view of the console lying on its face, new speakers on the left and the old speaker baskets on the right.

Chris Campbell


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