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  #16  
Old 05-10-2016, 11:04 AM
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maxhifi maxhifi is offline
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I've painted furniture before, and been happy with the result. A good job for me takes multiple coats and tons of work, and of courSe fully stripping the unit down. I think you could do a nice job with a little elbow grease in the preparation stage. Think of it like painting a car, the result depends 100% on attention to detail. If it's worth the effort or not is another question - I for one don't like those BSR changers, or their cartridges, and that 4" speaker in parallel with the big one on that big resonant Masonite front panel is going to give a nasty double peak in the bass region. I think at the time this was sold one would have been far better off spending the same money on a portable record player of somewhat higher quality, from a performance standpoint.
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  #17  
Old 05-11-2016, 09:38 AM
dieseljeep dieseljeep is offline
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Man that thing just defines cheap
In the early 60's, a friend and I went to Sears, with his parents. They wanted to look at the $88.00 stereo, such as the one shown. Naturally, they were not impressed with the sound quality. They ended buying one for around three times the money. Actually a great unit, Warwick built.
Maybe, the one shown, might've been bought from the catalogue, instead of the retail store.
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  #18  
Old 05-11-2016, 03:21 PM
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DavGoodlin DavGoodlin is offline
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When it comes to putting $$ in, look before you leap. I offer a different Sears as an example. Pardon the thread creep but I believe this is german to the discussion, IMHO.

First the console:
This Sears came from a yard sale last summer for $20. It was grimy but dry and complete with ALL the hang tags, service manual, parts list and schematic. Model 6066/528.63560, a 1965 Warwick-built SS chassis with Crescent changer/EV150 cartridge. It has a rear connection and slide switch for connecting 8-ohm remote speakers. The 10" speakers are 16 ohm with NP cap to 16 ohm 5" and 30 ohm 3" cone tweets. If you move the slider to use both internal and external speakers, a 22 ohm resistor is placed in series with the ext spkr screws AND an 8-ohm is then placed in series with the internal speakers.

The condition. I saw no evidence of any servicing after removing 20+ screws hold the back cover. I dutifully cleaned the selector and pots with DeOxit.

The receiver barely made sound and only when tuned to the usual strong stations, I figured the electrolytic coupling caps needed replacement so I got right to work and replaced the 4-3mf and two 150mf output coupling caps. Little improvement was noted and voltages on the drivers-outputs were consistent with the schematic. I got healthy hum when putting my fingers on the phono preamp input.
It sounded just like two bad speakers, so I pull one of the 10 inchers - the cone, compliance and voice coil was in great condition and not rubbing. It even passed Reece's patented thump test, when I smacked the magnet with my palm, it was met with a solid "thunk". OK....
Was the radio and discriminator/mpx demod section at fault? So I bridged new caps and checked voltages there - nothing improved

OK, now lets assume this unit has a receiver problem and serious bench time with signal generators are required Next!

What if we just do the record changer restoration and it comes alive??? OK but that is more work.
Then I looked at the cart and the stylus and pickup bridge was gone, yet it made noise when rubbing around where it would be. I just happened to have used cartridge and bracket that would work, an Astatic 710 (Euphonics style) with flat connectors just like the OEM E-V cart. I refused to rob any of my 3 or 4 Magnavox Micromatics that have a EV-150/158, those consoles might just be less of a PITA than this one has been.

The idler pulley is a small tire- big tire type, no flat spots or nicks. Cleaned up with rubber renu, and put back on. The platter started to spin but with lots of noise. Now what??? Looking very closely at the platter then the aluminum drive turret on the motor answered that one, the ":wedding cake" was worn down at each step such that the pulley could not make solid flat contact on both 45 and 33 rpm. More parts neededof course.. then I spun a good record anyway and it sounded just like the radio

OK, REALLY what can I expect from a worn out cart/stylus and anyway.
The last straw came when I connected a small portable CD player to the phono input and IT sounded as crappy as both the record and the radio.... back to square one. The amp IS the main problem after all this mucking about, let alone issues with the Crescent changer which are also present in a portable Sears I just bout a new Astatic 275d cart for.

If someone wants to refit this console with another record changer and receiver chassis, they can have at it for a song. It also has a factory schematic but the 5-year warranty on the transistors has passed and I suspect that IS the real problem. Anyway, where can you get good cheap germanium replacement transistors anyway?. The only thing this console is good for is the MCM walnut cabinet, still dirty - at least I'm smart enough after all these years to clean-refinish and detail ONLY if I can listen to it play nicely while doing so.

But I have too many more promising and frankly interesting units (think RCA-Magnavox-Motorola- Philco) to restore, plus paying jobs to occupy my limited time and finance the parts Ill need.
Besides, nobody is beating down my shop door to buy these old ceramic cart units anyway:boring
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Last edited by DavGoodlin; 05-11-2016 at 03:40 PM. Reason: add paragraph spaces
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  #19  
Old 05-11-2016, 05:35 PM
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maxhifi maxhifi is offline
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New germanium transistors can be had on eBay from Russia for decent prices, but are not direct fits. If you're a YouTube fan shango066 has a couple videos dealing with replacing germanium transistors with silicon or Russian substitutes which are pretty interesting.

I agree though, repaired junk is still junk. I've had similar luck (or lack thereof) with low quality equipment. I restored a console with the same horrible bsr as that silvertone -$: two 50EH5s for outputs - and even worse speakers. It was definitely not worth the work, it just sucks!

On this topic, americanradiohistory is a website with a huge archive of old magazines. One of the is "RCA Engineer". Some articles are about designing console stereos. Once you see how much thought was put into the good ones (like RCA) it is very obvious why they are better than the bad ones!

Last edited by maxhifi; 05-11-2016 at 05:41 PM.
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  #20  
Old 05-11-2016, 08:05 PM
dieseljeep dieseljeep is offline
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Quote:
Originally Posted by DavGoodlin View Post
When it comes to putting $$ in, look before you leap. I offer a different Sears as an example. Pardon the thread creep but I believe this is german to the discussion, IMHO.

First the console:
This Sears came from a yard sale last summer for $20. It was grimy but dry and complete with ALL the hang tags, service manual, parts list and schematic. Model 6066/528.63560, a 1965 Warwick-built SS chassis with Crescent changer/EV150 cartridge. It has a rear connection and slide switch for connecting 8-ohm remote speakers. The 10" speakers are 16 ohm with NP cap to 16 ohm 5" and 30 ohm 3" cone tweets. If you move the slider to use both internal and external speakers, a 22 ohm resistor is placed in series with the ext spkr screws AND an 8-ohm is then placed in series with the internal speakers.

The condition. I saw no evidence of any servicing after removing 20+ screws hold the back cover. I dutifully cleaned the selector and pots with DeOxit.

The receiver barely made sound and only when tuned to the usual strong stations, I figured the electrolytic coupling caps needed replacement so I got right to work and replaced the 4-3mf and two 150mf output coupling caps. Little improvement was noted and voltages on the drivers-outputs were consistent with the schematic. I got healthy hum when putting my fingers on the phono preamp input.
It sounded just like two bad speakers, so I pull one of the 10 inchers - the cone, compliance and voice coil was in great condition and not rubbing. It even passed Reece's patented thump test, when I smacked the magnet with my palm, it was met with a solid "thunk". OK....
Was the radio and discriminator/mpx demod section at fault? So I bridged new caps and checked voltages there - nothing improved

OK, now lets assume this unit has a receiver problem and serious bench time with signal generators are required Next!

What if we just do the record changer restoration and it comes alive??? OK but that is more work.
Then I looked at the cart and the stylus and pickup bridge was gone, yet it made noise when rubbing around where it would be. I just happened to have used cartridge and bracket that would work, an Astatic 710 (Euphonics style) with flat connectors just like the OEM E-V cart. I refused to rob any of my 3 or 4 Magnavox Micromatics that have a EV-150/158, those consoles might just be less of a PITA than this one has been.

The idler pulley is a small tire- big tire type, no flat spots or nicks. Cleaned up with rubber renu, and put back on. The platter started to spin but with lots of noise. Now what??? Looking very closely at the platter then the aluminum drive turret on the motor answered that one, the ":wedding cake" was worn down at each step such that the pulley could not make solid flat contact on both 45 and 33 rpm. More parts neededof course.. then I spun a good record anyway and it sounded just like the radio

OK, REALLY what can I expect from a worn out cart/stylus and anyway.
The last straw came when I connected a small portable CD player to the phono input and IT sounded as crappy as both the record and the radio.... back to square one. The amp IS the main problem after all this mucking about, let alone issues with the Crescent changer which are also present in a portable Sears I just bout a new Astatic 275d cart for.

If someone wants to refit this console with another record changer and receiver chassis, they can have at it for a song. It also has a factory schematic but the 5-year warranty on the transistors has passed and I suspect that IS the real problem. Anyway, where can you get good cheap germanium replacement transistors anyway?. The only thing this console is good for is the MCM walnut cabinet, still dirty - at least I'm smart enough after all these years to clean-refinish and detail ONLY if I can listen to it play nicely while doing so.

But I have too many more promising and frankly interesting units (think RCA-Magnavox-Motorola- Philco) to restore, plus paying jobs to occupy my limited time and finance the parts Ill need.
Besides, nobody is beating down my shop door to buy these old ceramic cart units anyway:boring
I'm really reluctant to work on early solid state, because of the germanium transistors. They seem to get weak, like a vacuum tube.
Many years back, I was having trouble with an Emerson 888 transistor radio. I went to the Emerson distributor for a replacement oscillator transistor. The technician said, it probably didn't need one. Just heat up the transistor with a soldering iron and it'll come back to life. Sure enough, it did.
What say, fellow VKers.
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  #21  
Old 05-11-2016, 08:44 PM
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Quote:
Originally Posted by dieseljeep View Post
I'm really reluctant to work on early solid state, because of the germanium transistors. They seem to get weak, like a vacuum tube.
Many years back, I was having trouble with an Emerson 888 transistor radio. I went to the Emerson distributor for a replacement oscillator transistor. The technician said, it probably didn't need one. Just heat up the transistor with a soldering iron and it'll come back to life. Sure enough, it did.
What say, fellow VKers.
Neat, I'll remember that trick.
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  #22  
Old 05-12-2016, 08:23 AM
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DavGoodlin DavGoodlin is offline
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I'll fire up the iron and hit the amp transistors once Dave, its worth one last shot.

This console is a good candidate for a retrofitting and I have a spare Magnavox Astrosonic and Micromatic - http://vintagehifi.net/index.php/topic,1476.0.html
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  #23  
Old 05-17-2016, 08:02 PM
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radiotvnut radiotvnut is offline
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I dug into the record player; and, unfortunately, the primary on one of the output transformers is open. It's also unfortunate that it's not a regular AA5-style output transformer. This one has a separate secondary feedback winding and who knows where I'll find one of those. This is a model 6051 and it's not in the Sam's index.
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  #24  
Old 05-18-2016, 01:12 PM
dieseljeep dieseljeep is offline
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Originally Posted by radiotvnut View Post
I dug into the record player; and, unfortunately, the primary on one of the output transformers is open. It's also unfortunate that it's not a regular AA5-style output transformer. This one has a separate secondary feedback winding and who knows where I'll find one of those. This is a model 6051 and it's not in the Sam's index.
Did you look under the 132 chassis numbers. Also look at the numbers around the 6051 listings. It might listed under 6050,6052 etc. Cabinet differences!
I check Beitmans first, that is look at the schematics listed under Sears, Arvin.
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  #25  
Old 05-18-2016, 02:17 PM
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maxhifi maxhifi is offline
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Quote:
Originally Posted by radiotvnut View Post
I dug into the record player; and, unfortunately, the primary on one of the output transformers is open. It's also unfortunate that it's not a regular AA5-style output transformer. This one has a separate secondary feedback winding and who knows where I'll find one of those. This is a model 6051 and it's not in the Sam's index.
Could always do some re-engineering. Some RCA amplifiers took feedback directly from the primary winding of the output transformer, this could be made to work in your case with a normal AA5 transformer and some small circuit changes.
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  #26  
Old 05-18-2016, 04:43 PM
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That's what I plan on doing - just taking the feedback from the plate of the output tube.
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  #27  
Old 05-19-2016, 11:06 PM
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Here's a crude schematic I drew. It's odd that the tone controls are in the cathode circuit of the 12AX7 and one of the leads from the extra winding on the transformer goes back to the tone control. If this was a handwired amp, it would be much easier to modify it. However, since it's a PC board, it's going to be harder to deal with. Leave it to Sears to come up with some goofy circuit design.

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  #28  
Old 05-20-2016, 01:18 AM
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Quote:
Originally Posted by radiotvnut View Post
Here's a crude schematic I drew. It's odd that the tone controls are in the cathode circuit of the 12AX7 and one of the leads from the extra winding on the transformer goes back to the tone control. If this was a handwired amp, it would be much easier to modify it. However, since it's a PC board, it's going to be harder to deal with. Leave it to Sears to come up with some goofy circuit design.

I'd look at the good half of the amp. Is the amplitude of the feedback winding is the same or lower than the speaker winding? Is there significant DC voltage across the feedback winding? If both answers are yes, then just use a single secondary spare and use the one secondary to drive feedback and speaker at once. If only the second is no, then use a large capacitance value to couple the voice coil winding to the feedback circuit so you are not sending tons of DC through the speaker. If it works decently on one channel you may want to do it for both so there is not a tonal mismatch between channels.
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  #29  
Old 05-20-2016, 08:58 AM
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To find out the transformer ratio, apply about 400Hz at the amplifier input, and measure the AC voltages at the primary, secondary, and feedback windings of the good transformer with a VTVM.

I like Electonic M's idea of using the speaker voice coil winding for feedback. No significant DC will make it through the tone control so no need for a blocking cap. If it was off the plate that would be another story.

Anyway once you know the transformer ratio, you will know if you need to change anything to use the speaker winding. If it's significantly different, you can change the value of the 680 ohm reaistor up in value to increase the amount of feedback, and down to reduce it. For example if the feedback winding puts out more voltage than the speaker voice coil winding, you would want to increase the value of the 680 ohm reaistor, and vice
Versa.

In a perfect world this should be accompanied by a change in the 3.3k cathode bias reaistor to keep overall current the same.

If you hook it up and it oscillates, swap the voice coil winding leads. Also make sure the voice coil windings are not grounded anywhere.

I wonder if this chassis was also used in a model with one mono woofer and two separate mid/tweeters. If it was that would explain why the feedback winding was separate in the first place. This thing doesn't look less cheap after analyzing the circuit, but I am happy to see it used negative feedback! (That ought to help control the response of those speakers a bit)

Last edited by maxhifi; 05-20-2016 at 09:27 AM.
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  #30  
Old 05-20-2016, 09:27 AM
dieseljeep dieseljeep is offline
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Quote:
Originally Posted by radiotvnut View Post
Here's a crude schematic I drew. It's odd that the tone controls are in the cathode circuit of the 12AX7 and one of the leads from the extra winding on the transformer goes back to the tone control. If this was a handwired amp, it would be much easier to modify it. However, since it's a PC board, it's going to be harder to deal with. Leave it to Sears to come up with some goofy circuit design.

[]
It wasn't Sears, that came up with the design, it was Arvin.
Evidently, they had some pretty sharp engineers, to go to that extent to design an inexpensive product. You don't even see that in the higher-end makes, Zenith et al.
I have an Arvin sourced, Silvertone table radio with twin speakers and push-pull output. Zenith never did that!
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