Classic Hifi Care

Picked up this solid state suitcase portable ($5 on marketplace) with the idea of robbing the changer to upgrade my 1948 Olympic console to enable playing LPs, but now I'm feeling reluctant to destroy this nicely equipped little guy! Speakers and amp all there, in good visual condition. Apparently the same components used in the small SC-601 console. The cabinet sides and bottom are in rough shape, though, water damage apparently. Heavy cloth/plywood construction. Lots of changer manuals in the downloads section, but what model is this one? I haven't removed it yet. That's an EV-158 cartridge, sans stylus, but Gary has it.

From the 1963 catalog:

It seems a shame to use a nice Magnavox stereo for parts. You might find one of those ubiquitous three-in-one combination stereos with a VM or BSR changer that would make an easier changer swap than would the Collaro. Good luck....

It looks like a Collaro 600 series changer to me.

Bill

If it can be saved it looks like it would be a good one to have. Nice price too.

Here's a few shots of the works, maybe that's a chassis number? The PT in the amp is tiny, and no heatsinks on the output transistors, so only a few watts per channel, I suppose. All germanium, but RCA hopefully. Anybody have a source for a schematic? I couldn't find one in Downloads, and elsewhere on the web I looked were close, but not specific to this model. Lots of electolytics to replace, for sure.

Sams 644 may get you as close as you are gonna get. The speakers were made by Chicago Telephone Supply in the 33rd week of 1964. If the stereo currently works, you may be able to get by with changing the components using the values that are there without a schematic. Good for you for attempting to save it. Good luck......

Magnavox was vague with specifics on model numbers. They did a lot of "mixing and matching" with the various components. Many times, it is nigh impossible to find the exact schematic you need, so you have to use your imagination a bit. I never did find an exact schematic for the radio tuner or the TV chassis in my Stereo Theater.

I did find a schematic on Radiomuseum for the chassis 505-01-00. In the component location drawings, it looks like mine, though the photo of the portable stereo unit is not exactly the same. So, it's probably pretty close! I'll put a PDF in the Downloads section if anyone is interested. The bass control is very strange, it appears to be just a voltage divider between the two input channels! Can't understand how that works....

From the photo, it looks like the amp's output transistors are transformer-coupled to the prior stage. My Heath AA-22 is the same.

Chris Campbell

Removed the changer, here's the label. And, I was bummed when I first got this guy, no 45 adapter. But, turns out it was hiding at the back of the changer drawer! I'm impressed that they measured wow and flutter at the factory. Does the W prefix signify something different than the M, K, & L prefixes?

And rumble at 3 frequencies. Collaro was a competitor with Garrard in the changer world of the time, I think.

Chris Campbell

Well, turns out both of the 7.5" (they are not 8") speakers are shot, one is seized and both cones are rotten and insect-eaten. This thing must have been sitting in water at some point. Good news is the changer and amp weren't damaged by water. The 4" tweeters are perfect. Somebody must have worked on the changer at some point, the grease is not in too bad shape. But they lost the E-clip that holds the platter and spindle in place which explains why the platter was not seated when I first opened it up! I had an o-ring that works (like VM uses) to secure the platter and the spindle works just fine. After a little oil and grease on a few places, cleaning the idlers, and shoring up motor mounts, it works like a champ--selects the correct record size, drops record, shuts off, etc. The motor mounts were pliable, but a little short, so I used some rubber from on old squeegee to add a little thickness (I know, this is a kludge, but I'll check for motor noise later). It ran a little fast, the idler was partially hitting the 45 portion of the speed spindle, so I adjusted the height and now it's spot-on! Tracking force was already set at 3 grams, on spec. I know I'm lucky that it was in such good shape! Waiting on the stylus.

I found the correct changer service manual at Vinylengine.com:
https://www.vinylengine.com/library/mag ... atic.shtml

Sorry, the Vinylengine link I gave above won't work, but #Hotwax referenced that manual in a post on ARF via this link:
https://antiqueradios.com/forums/downlo ... ?id=500973

Even with bad woofers and a few other things the 5 bucks was well worth it.

Bill

William wrote: ↑Tue Sep 23, 2025 11:10 pm Even with bad woofers and a few other things the 5 bucks was well worth it.

Some people pay $5.00 for a cup of coffee. It's gone in 5 minutes. The little portable will give joy for many more years.

[I will admit that I ordered some high-end coffee on the recent vacation in Santa Fe, but we're allowed to get a little wild and crazy on vacation, right? At home, I make coffee at the office, two days' worth at a time for reheating in the microwave, which will make coffee lovers barf.]

Chris Campbell

I'm working on the amp now, all electolytics replaced and controls deoxed. Out of curiosity, I checked the speakers for continuity: 3 out of 4 open! I'm guessing the output caps were breaking down and feeding the 18 volts VCC directly to the voicecoils sometime in the past (no power cord when I got it).

The good news is that all voltages check ok, but one channel is mostly dead, so I've gotta find that issue.
The changer was making some rustling noises while running, coming from the platter idler. I didn't want to spend $ for a replacement, and the original was pretty pliable except for a hard, uneven glaze on its edge. So I chucked it in my drill and ran it against a 100 grit sandpaper block until all the hardened edge was gone and "fresh " rubber was exposed. Now it's silent running and the numbers are much better! I have some intermittent connection issues with the cartridge which I need to fix before I can see if the audio will be OK when actually playing a record.

It's cool that there are some schematic symbols on the PCB underneath and traces outlined on top. It sure helps with diagnosis.

Chris Campbell

Yes, Chris, it's helpful, but what is really frustrating is that the component and test point markings are completely different from my schematic!

The amp problem turns out to be that one channel is oscillating, swamping the power supply. Haven't figured out what's causing it yet ....

Well, the oscillation was because my left channel test speaker had a loose connection on the rear terminals, and I didn't realize it, so that channel didn't like an open circuit load! Now the little amp appears to work just fine.

It's not a very sophisticated amp, of course. What's really strange is that the cartridge inputs are connected together through two 100k resistors, with their center tap going to a 7 meg pot to ground, which is the "bass" control (lower left corner). Must be highly dependant on the particular cartridge electrical characteristics in order to work? And the balance control is a single pot connected between channels which just fades one channel or the other to ground. Methinks this is to save $ on pots!

Thanks to RadioMuseum, here's a schematic (I paid and joined up after I downloaded this)

Correction on the balance control --it's connecting the negative feedback circuit of each channel together through that pot! I can't figure out how that works, and in practice it really sounds crummy: there is a significant change in the fidelity/loudness as the control is rotated, with the center position actually sounding weaker and worse!

Also had a strange low frequency oscillation occur when I connected a larger speaker to one channel, varying from about 30 to 75 Hz, depending on the positions of the volume and balance controls. I don't know what the impedance of the original speaker array was, since they are shot, but apparently the amp prefers a load above 8 ohms. The oscillation doesn't happen with the two 8 ohm test speakers in series.

Also found a better schematic (matches the component markings on the circuit board) in the 1966 Beitmans book.

Check C3/6 and C10/13?

Chris Campbell