General Electric RP-1590-A Stereo

Page 1 of 4 1, 2, 3, 4  Next

Go down

General Electric RP-1590-A Stereo

Post by Wildcat445 on Mon Dec 15, 2014 11:57 pm

This stereo has been an off and on project for the better part of 15 years. The schematic can be found in Sams Photofact 609, Folder 5, if you would care to follow along. I have pictures that I will post as soon as I get them downloaded to my computer.

This stereo was purchased new in 1961 by the father of the man who painted my black Buick. We have been friends and business associates for probably 30 years and he has generally aided and abetted my radio hobby. Our shops were back to back when I was in the auto restoration business, and he lets me use his drive on lift when I need to tinker with the Buick. He used this old stereo in his shop until it went on the blink, and was hauled to his parts room and forgotten.

He dug this old thing out when I still had my shop, maybe 12 years or so ago. It is your basic early-'60's stereo with two 6 inch speakers in the main cabinet and two more 6 inch speakers that swing out from the cabinet for "expanded stereo" whatever that is. It has a VM changer, Electro-Voice 26 cartridge. It utilizes a transformer power supply with 5Y3GT rectifier, 12AX7 audio amplifier and two 7189 output tubes for single ended stereo audio output. It has your typical GE printed circuit chassis, reinforced by a metal plate, and has been thoroughly baked by the tubes and by poor cabinet ventilation. This particular instrument was modified sometime when Don was in college by adding a two tube pre-amp and a Pickering unknown model magnetic cartridge. Also added were about six switches to control the amp, turntable and speakers in ways still unknown to me and with tape input, tuner input and tape output jacks added to an already crowded cabinet. This thing was originally just a record player. All the added doodads did was to make a fairly competent stereo basically an unusable pile of garbage that sat on long chrome legs. Like many instruments that have been converted from ceramic cartridge to magnetic, the VM changer suffered from tracking, skating, and changer mechanism woes, rendering any possible benefits of the magnetic cartridge basically worthless. I took a look at this thing and told Don that if he wanted me to get interested in the project he would have to find a parts set and basically start over. That put the project on hold until this past summer when Don found an old dog-eared parts set that was in worse shape than the one he had, except it was basically complete and had not been hacked. There were no wing speakers, but that was not an issue.

I don't have more than triage facilities here, so I pressed my long-suffering frau's kitchen island into service as a stereo repair rig. I had no Variac, no isolation transformer, no dim-bulb so this was gonna be a down and dirty repair. Not pretty. I put these two stereos side by side on the island, ran a cheater cord to the original stereo and found out what I had. Basically a one-channel stereo with the right channel dead as a two-dollar mule. I found the audio output transformer primary was open. That one was now the parts set. I fired up the parts set and found the left channel dead in it. The motor ran in the TT, but the platter did not turn. I pulled the platter and found most of the turret parts gone. The motor was spinning, but that was it. No drive tire. Fortunately the TT ran in the original instrument. I got out the Sams and started running voltages and measuring resistance to try to find out why I had no left channel. I found no screen voltage to the 7189. There was screen voltage on the other tube. I dug that tightly-packed chassis out and found a burned trace in the PCB. I soldered in a piece of wire across the broken trace. I now had screen voltage. The rest of the voltages on the chassis proved to be fairly close, so I soldiered on. I found the left channel now not dead, but it was barely audible, very weak. I got to digging some more and found the problem to basically be between the cartridge and the grid of the 12AX7, pin 2. What is there is a PCB with the treble, bass, loudness, balance controls mounted on it. The "Expanded Stereo" switch is separate, but mounted on the same bracket. With the aid of a good light, I found a place on this PCB with a trace that looked not very good. It checked with continuity, as did the wire to the cartridge. But it didn't look right to me. I decided to use the part out of the original stereo, which looked really good. There was already a couple repairs on that board, so replacing it with the other one seemed a better plan. This operation, which took me a couple hours by the time I cleaned all the controls and a couple other little incidentals, worked out to solve that problem. I now had two channels that worked somewhat the same and I can now forge ahead.

The next project with this rescue is the turntable. I am going to use the original turntable, with the parts TT's cartridge and wiring. I may still need a drive tire and certainly a new needle after I get the TT cleaned and lubed and ready for service. Don is going to handle cabinet restoration himself, since he has an upholstery guy who can handle the tolex and grille cloth operations necessary. He has some kind of whiz bang computer program that can reproduce the graphics on the cabinet.

WC

Wildcat445
Member
Member

Number of posts : 5168
Registration date : 2011-09-19

Back to top Go down

Re: General Electric RP-1590-A Stereo

Post by Guest on Tue Dec 16, 2014 12:34 am

Sounds interesting, looking forward to the photos! Smile

Guest
Guest


Back to top Go down

Re: General Electric RP-1590-A Stereo

Post by Bill Cahill on Tue Dec 16, 2014 2:49 pm

Sounds very interesting, and, I'm looking forward to pictures. I'd also re cap the unit, and, especially if they are paper, replace the electrolytics.

_________________
Please also join us here;  http://videokarma.org/index.php
avatar
Bill Cahill
Admin
Admin

Number of posts : 4583
Age : 66
Registration date : 2008-03-12

Back to top Go down

Re: General Electric RP-1590-A Stereo

Post by Wildcat445 on Tue Dec 16, 2014 8:15 pm

The amp chassis has ceramic caps, so there are no paper ones. It has filter caps, a cathode bypass cap and the crossover caps, all of which will get replaced. There is no hum, but they are 50 years old. I am going to soup up the power supply like I do with my Magnavox stuff. It actually does not sound too bad for what it is. I haven't checked the resistors yet, but I'll wager that some are drifted high.

I'll get the pics downloaded when I get a minute. There is a real rats nest in the original instrument. They could not use the tube shields on the add-on preamp. They hit the bottom of the turntable. You could not crank down the turntable bolts without breaking the tubes in the preamp. The job was a total hack. It never worked right.

WC

Wildcat445
Member
Member

Number of posts : 5168
Registration date : 2011-09-19

Back to top Go down

Re: General Electric RP-1590-A Stereo

Post by Wildcat445 on Tue Dec 16, 2014 9:53 pm

If I have done this right, the pictures I promised are on the way.

This is the parts set that we will use for the final product.



The amp and wiring.



The VM changer.


Wildcat445
Member
Member

Number of posts : 5168
Registration date : 2011-09-19

Back to top Go down

Re: General Electric RP-1590-A Stereo

Post by Wildcat445 on Tue Dec 16, 2014 10:02 pm

Here is a picture of one of the issues I had to address. Look on the left hand lower side of the PCB and you can see how black it looks.


Wildcat445
Member
Member

Number of posts : 5168
Registration date : 2011-09-19

Back to top Go down

Re: General Electric RP-1590-A Stereo

Post by 75X11 on Tue Dec 16, 2014 10:22 pm

I prefer those units with the separable speakers.
avatar
75X11
Member
Member

Number of posts : 4900
Age : 61
Registration date : 2013-03-10

Back to top Go down

Re: General Electric RP-1590-A Stereo

Post by Wildcat445 on Tue Dec 16, 2014 10:30 pm

What little I have heard of this one is fairly impressive for what it is. I haven't figured out the red grille cloth yet, although it is quite attractive in person. It obviously is not correct. If I understand correctly, you can either listen to the speakers in the cabinet or turn on both the internal speakers and the separable wing speakers. This thing was probably the top of the line in portable units. This same chassis and TT was used in a console. I thought at first that this was a three-channel, but it's not.

WC

Wildcat445
Member
Member

Number of posts : 5168
Registration date : 2011-09-19

Back to top Go down

Re: General Electric RP-1590-A Stereo

Post by 75X11 on Tue Dec 16, 2014 10:45 pm

Probably red to point up the speakers. That was a mighty special unit when new.
avatar
75X11
Member
Member

Number of posts : 4900
Age : 61
Registration date : 2013-03-10

Back to top Go down

Re: General Electric RP-1590-A Stereo

Post by Bill Cahill on Tue Dec 16, 2014 10:47 pm

I have a Symphonic portable stereo that puts out up to 5 watts of audio in each speaker. It has also a deluxe VM changer with a 12" extension on the turntable. Smaller tone arm, though. You're lucky yours doesn't have the usual GE made changer. They were crummy.
Mine uses only extension speakers with a tweeter, and, a woofer.
There are two sets of speaker jacks on the back of the unit. Two,, one for each channel, are wired in reverse of the main ones. I found that when you connect four speakers, it sounds like an early version of quadrophonic. It's only two channels, but, reverse second set of speakers puts out an interesting stereo effect.
It's actually a very fine machine with excellent bass, and, treble. Single ended 6BQ5 tubes drive the speakers. has a 12AX7 preamp, and, a 6CA4 rectifier...
Controls are loudness, bass, treble, and, balance.
Except that the handles on the speakers tend to rattle with the bass, which drives me crazy, I really love the machine....
Symphonic didn't only build children's record players like everyone thinks. This was an expensive machine when new....

_________________
Please also join us here;  http://videokarma.org/index.php
avatar
Bill Cahill
Admin
Admin

Number of posts : 4583
Age : 66
Registration date : 2008-03-12

Back to top Go down

Re: General Electric RP-1590-A Stereo

Post by Wildcat445 on Tue Dec 16, 2014 11:10 pm

Here is a picture of the hack. Just a huge pile of shielded wiring. Lots of slide switches, one three position switch for record, tape, and tuner. A rocker power switch to shut off the turntable motor and still allow the amp to work. It is semi-wonky and caused me untold grief before I figured out what it did. I still don't know the purpose of the slide switches for sure. I think they replace the original "expanded stereo" switch, but I have no idea why anyone would do that.


Wildcat445
Member
Member

Number of posts : 5168
Registration date : 2011-09-19

Back to top Go down

Re: General Electric RP-1590-A Stereo

Post by Wildcat445 on Tue Dec 16, 2014 11:43 pm

Bill, IIRC, this changer is a semi-custom unit made just for GE by VM.  It has the heavy-looking tone arm on it, which is really quite light.  Some of those had a contraption on them to clean the needle, or some such bilgewater.  I am eternally grateful that this particular changer is not so equipped.  The changer in the parts unit has been parted before.  It has a General Industries motor that works okay.  The original changer also works pretty well, until it cycles.  Then it stalls.  It needs "the touch" that they all need.  I'll have to change the needle and maybe the drive tire and go from there.  The usual cleaning and lubing, of course, including the motor.  I appreciate that VM is a workhorse and that parts are available for them, but it sure is a cheesy looking contraption compared to a Collaro.



WC

Wildcat445
Member
Member

Number of posts : 5168
Registration date : 2011-09-19

Back to top Go down

Re: General Electric RP-1590-A Stereo

Post by Ragwire on Wed Dec 17, 2014 11:08 pm

The preamp wiring looks more recent than I expected--like a 1980s job or something.
avatar
Ragwire
Member
Member

Number of posts : 526
Registration date : 2013-05-20

Back to top Go down

Re: General Electric RP-1590-A Stereo

Post by Wildcat445 on Thu Dec 18, 2014 12:01 am

I am not sure when this instrument was modified, but I would say you are pretty close.

WC

Wildcat445
Member
Member

Number of posts : 5168
Registration date : 2011-09-19

Back to top Go down

Re: General Electric RP-1590-A Stereo

Post by Wildcat445 on Sun Dec 21, 2014 7:06 pm

I put some more time into this thing.  I have learned two things.  First, this thing does not sound that bad, for what it is.  Second, I sprained my arm patting myself on the back.  It has developed another fault.  Or I did not totally fix the first fault I found.

The original unit was modified with a Pickering 480-E cartridge.  I don't know it that is good or bad, but that is what somebody hacked into it.  It sounded okay, I guess.  Not great though.

I changed the tone arm from the parts changer to the original changer.  The cartridge in there now is a ceramic Sonotone, again of unknown model.  It actually sounds better to me than the Pickering did.  But, unfortunately, not for long.  I played three records, turned sides and all hell broke loose.  I started getting a scratching sound out of the speaker, then a small pop, then a silent left channel again.  If I shut the stereo off, let it cool about 15 minutes, it comes back on with both channels.  After a couple minutes, more scratching, a little pop, and no left channel.  If I turn the balance control full to the left channel, you can hear audio, but it is very weak and distorted.  Shut it off, let it stand, it comes back on for another couple minutes.  There are no paper caps in the amp.  If it had paper caps, I would suspect a coupling cap.  It has a .01 ceramic coupling caps for the 7189 tubes.  Ceramic caps don't EVER go bad, now do they?  

What I have done thus far is to check all the grounds, all my solder connections, reheated them just for grins, and have run what voltages I could without removing the chassis, which is a horrible job that I will do whatever to not have to do that.  I fear that is my next step.  I have tentatively eliminated anything ahead of the 12AX7.  Methinks that the next place to look is between the 12AX7 and the 7189 for the left channel.  I am going to try to include the schematic.  Please bear with me, as this is new territory.

Great, my file type is not allowed!  What kind of file type do I have, and what kind do I need.  I think I did a JPEG, but I sure won't swear to that.

One more time.



Sorry that the schematic is on its side.  I'm probably lucky it's here at all.  I did some kind of Adobe Reader thingy that messed things up.  I need to take time to read the screen when I do this stuff.  

It appears to me that the main speakers and the wing speakers are connected in series.  The audio should not work at all with the wing speakers disconnected, but they do.  At least ONE of them does!  Connecting the wing speakers makes no difference concerning this new issue.  C11 is the coupling cap that I am suspecting of causing my problem.  I have swapped tubes around, with no change.  The "Expanded Stereo" switch does nothing as far as I can tell.  I am going to change the 90uf caps, but I don't think they are causing my problem.  I shorted them out for a test, and it made no difference.  I kluged the changer in this instrument to the tape input of my Magnavox Symphony, and the cartridge appears good.  I have changed the shielded cables from the changer to the PCB that I changed earlier with no change.  

WC


Last edited by Wildcat445 on Sun Dec 21, 2014 9:37 pm; edited 1 time in total

Wildcat445
Member
Member

Number of posts : 5168
Registration date : 2011-09-19

Back to top Go down

Re: General Electric RP-1590-A Stereo

Post by Wildcat445 on Sun Dec 21, 2014 7:53 pm

More pictures of the GE stereo project.

The rear of the original instrument, showing the tape and tuner inputs that were added.



The rear of the replacement instrument, the one we will restore.



The pre-amp that had been installed to accommodate the Pickering magnetic cartridge.  It is as tight as it looks.  One tube can not sit straight.  The tube shields contacted the bottom of the changer.  The changer could not be tightened down for transport or the tubes could be broken.  This shot shows the extra switches and the guitar amp plug that was added.  Whoever did this thought of everything!



The Pickering magnetic cartridge in the original instrument.  This table appears to have an Alliance motor, while the parts instrument changer has a GI.  This tone arm had been ground on so it was not usable for the ceramic cartridge. Note the kluge of plastic that was used to align the cartridge, not successfully, I might add. This thing has proven to be more of a mess than I remembered.



WC


Last edited by Wildcat445 on Sun Dec 21, 2014 8:07 pm; edited 2 times in total

Wildcat445
Member
Member

Number of posts : 5168
Registration date : 2011-09-19

Back to top Go down

Re: General Electric RP-1590-A Stereo

Post by 75X11 on Sun Dec 21, 2014 8:01 pm

You say you let the unit cool and it restored function. Got a hair dryer that you could focus on the suspect ceramic? Are those bipolar caps forming a crude crossover network? They may have a function.
avatar
75X11
Member
Member

Number of posts : 4900
Age : 61
Registration date : 2013-03-10

Back to top Go down

Re: General Electric RP-1590-A Stereo

Post by Wildcat445 on Sun Dec 21, 2014 8:23 pm

I have a hair dryer, but working room with the chassis in place is beyond tight. I have to remove the TT, jumper the plug and then figure out a way, none convenient, to wrestle the chassis while I try to take measurements. The rear speaker connections and the filter cap have to be removed in order to get enough wire to move the chassis. The motor board has to be removed. The knobs, the top trim, the front trim board all have to come out to work on the chassis. A Concert Grand is a piece of cake in comparison. It is possible that I overlooked another burned trace on the PCB.

I have not figured out the purpose of those 90uf caps. It appears that there is some sort of feedback circuit involved. I have jumpered those caps and it did not make a difference. I posted the diagram so that perhaps someone could clear this up for me. I have not run across a setup like this before.

Here is the instrument we will restore, and a shot of those caps.



WC

Wildcat445
Member
Member

Number of posts : 5168
Registration date : 2011-09-19

Back to top Go down

Re: General Electric RP-1590-A Stereo

Post by Wildcat445 on Sun Dec 21, 2014 9:48 pm

I was digging thru the original instrument, trying to make some sense of some of the controls.  I ran across what appears to be the original owners' manual, dated 12-8-61.  Apparently, it had been "missing" for several years, presumed lost.  The owners' manual does not say anything about the wing speakers having to be connected in order for the main speakers to work.  It certainly appears to me, per the schematic, that they do.  The "Expanded Stereo" selection is for "enhanced presence" by sending more treble thru the wing speakers, delivering "greater stereo enjoyment."  Hocus pocus if you ask me.  A gimmick.  Bilgewater.  I don't think the 90uf caps so employed have any effect on my dead channel, at least at this point.  Assuming that the wing speakers do have to be connected, a dirty or corroded connection at the speaker plugs might cause the problem I'm having.  Why it works okay for a couple minutes then quits, I have no idea.  I'm just throwing out ideas, pending my further checking.  This thing worked great when I played three records on one side.  When the instrument switched off, then it was restarted was when the trouble started.  I have a few more things to check.  I'm sure I'll get to the bottom of this eventually.  

The needle has an Astatic symbol on it.  The cartridge, however is a Sonotone 16T-SD.

I think I will clean up those speaker connections well before I forge ahead. I need to make sure that something simple is not causing me grief.

WC

Wildcat445
Member
Member

Number of posts : 5168
Registration date : 2011-09-19

Back to top Go down

Re: General Electric RP-1590-A Stereo

Post by Wildcat445 on Sun Dec 21, 2014 10:51 pm

I MAY have just had an "ah-ha" moment with this stereo.  I checked the right channel wing speaker plug and found it essentially shorted.  The "hot" terminal showed continuity to the "common" terminal.  That would account for why the right channel worked with the wing speaker disconnected.  I got to looking at notes I made during my preliminary investigation and found a notation about a "wonky right wing speaker plug-intermittently dead."  I remember my plugging in the right wing speaker and it killed the channel, so I unplugged it immediately.  The left channel wing speaker plug does not show continuity across the plug.  I have looked at the schematic over and over, and am convinced that the main speakers, listed as "6 inch, 3-4 ohms" are connected in series with the wing speakers "6 inch, 3-4 ohms."  The output transformers are listed as having "8 ohm" secondary impedance.  It would seem reasonable, considering this, that the wing speakers need to be connected for the audio circuit to be complete.  I may replace both wing speaker plugs to see if this eliminates the problem.  This has to be something simple.  This stereo worked just fine playing one side of three records.  I want to be sure of this before I pull the chassis and possibly chase my tail.  I also need to run the common negative connections on the wing speaker plugs all the way to the filter caps to make sure of good connection there.  Printed circuit chassis have different faults than hard wired chassis.  We all know how much grief a bad connection can cause. This is getting interesting now.

WC

Wildcat445
Member
Member

Number of posts : 5168
Registration date : 2011-09-19

Back to top Go down

Re: General Electric RP-1590-A Stereo

Post by 75X11 on Sun Dec 21, 2014 11:25 pm

Good work.
avatar
75X11
Member
Member

Number of posts : 4900
Age : 61
Registration date : 2013-03-10

Back to top Go down

Re: General Electric RP-1590-A Stereo

Post by Wildcat445 on Mon Dec 22, 2014 12:04 am

While I appreciate your good words, I'm not ready to take a bow just yet. At least I have an avenue of investigation. I'm not totally baffled. Yet. Shocked

WC

Wildcat445
Member
Member

Number of posts : 5168
Registration date : 2011-09-19

Back to top Go down

Re: General Electric RP-1590-A Stereo

Post by Wildcat445 on Mon Dec 22, 2014 12:19 am

You guys may be getting sick of this project, but I am having a ball!

I have been tinkering with the changer. It actually works pretty well. It changes records, (with a little help), it seems to track reasonably well, and it shuts off when the last record plays. So it seems like it will work with a little TLC. The drive tire slips,(hence the need for help) and one of the motor mounts is totally gone, the other two are pretty bad. I'm surprised it works at all.



The picture did not turn out very well, but perhaps you can see the condition of the motor mounts. The plan is to change the drive tire, motor mounts, and then clean and lube the motor and mechanism. And change the needle. Then check and set the tone arm pressure. I'm not sure what that should be, but I'll bet that Gary at VM Enthusiasts does. That should put the changer right.

WC

Wildcat445
Member
Member

Number of posts : 5168
Registration date : 2011-09-19

Back to top Go down

Re: General Electric RP-1590-A Stereo

Post by 75X11 on Mon Dec 22, 2014 1:11 am

You keep reporting, I'll keep reading. Those things kind of grab hold of you, don't they?
avatar
75X11
Member
Member

Number of posts : 4900
Age : 61
Registration date : 2013-03-10

Back to top Go down

Re: General Electric RP-1590-A Stereo

Post by Bill Cahill on Mon Dec 22, 2014 2:04 pm

I'm having more, and, more disc caps fail.
Even brand new ones.....

_________________
Please also join us here;  http://videokarma.org/index.php
avatar
Bill Cahill
Admin
Admin

Number of posts : 4583
Age : 66
Registration date : 2008-03-12

Back to top Go down

Re: General Electric RP-1590-A Stereo

Post by Sponsored content


Sponsored content


Back to top Go down

Page 1 of 4 1, 2, 3, 4  Next

Back to top

- Similar topics

 
Permissions in this forum:
You cannot reply to topics in this forum