Contemporary II turntable grounding question

Hi-
I have a Contemporary II console that came without a changer so I bought a used/unrefurbished Garrard 210 for it that seemed to play fine on a modern
more powerful amplifier. When I hook it up to the console, though,
the sound is weak and there's a buzz coming through the speaker. I'd attached the ground wire to the sheet of metal under where the changer is because it looked like the old record player was grounded there. A tape player attached to the same inputs on the fisher amp sounds fine as the tubes, sockets and selectors have all been tested/replaced and cleaned respectively. Can anyone tell me where to ground the record changer or if this sounds like I need a new needle /cartridge since they look like original GE VR-22.
thanks
Will

Contemporary II, you say . . . I just might be able to help. Which Contemporary II do you have? There was the mostly mono Fisher factory version that has the R-30S chassis and a three-way 15/8/4" speaker set-up to which could be added the 560 Stereo Companion for stereo. There was also a version with some sort of stereo speaker set-up installed in the Contemporary II cabinet that must have also included a mono power amp (the 30-A?). It was sold by Liberty Music Shops and possibly other high-volume music stores outside of NY metro area. If it's one of the later, you need to post some photos of that extremely interesting model. Even if it's one like mine, photos would still be of interest to the Fisher console tribe here on this forum.

Are you listening in stereo or mono? I would suspect some sort of cartridge or jack phase issue. If you've got your R-30S set up to play in stereo and the cartridge or the RCA jacks are wired out of phase that would explain the weak signal - I'm not sure about the hum. None of the Fisher console manuals I have for consoles from this period mention anything about grounding the changers. I don't think the RC-121 Mk. II in my Contemp. II has any wires other than the RCA pair and the power cord - though that metal plate below the changer compartment may have been wired to the changer chassis. I suspect grounding was achieved via the shielding on the RCA cables which connect to the chassis ground on the R-30S. It also occurs to me that if you are using the mono phono setting (with the dot, stereo is the one with the little triangle) it's also possible that the L and R channels are being summed and canceling out if they are wired out of phase.

Good luck. I'm looking forward to photos.

Carter

Did the changer work when you plugged it into the magnetic input of a test amp? If so, sounds like the console phono input is for a ceramic cartridge. You can get a phono premap, a little black box and inset it between the changer and console amp. The GE cartridge while as vintage as they come back in its day was considered to be a fine cartridge. As for the hum, when you get the cartridge issue resolved it may go away or then you can tackle it. You may need to wire to the amp and then do a touch test of the other end under the changer to find a good ground point. SOme changers and tables had dedicated grounding screws or points so you may find one on the table.

Thank you Brian and Red1!

The Contemporary II I have is the R-30-S chassis and originally had the Garrard Rc121 mkII (remember using it as a kid). I will try to post pictures
when I get this issue resolved.

While waiting for replies I took the 210 out of the console and set it in the cut out box that came with it. I screwed the ground wire into the metal plate and plugged the turntable rca's and plug into the amp. While the volume of the album was somewhat lower than I expected (maybe a somewhat worn stylus?) there was no hum . I had it set on mono phono(circle) and tried
with both rca plugged in and an rca combiner plugged into A channel only.
So the B channel is very weak but there's no hum or buzz. I guess the two channels are not being combined to mono for some reason. BTW The table worked quite well on the test amp (a Nikko from the 80's). When I put the changer back into the console the buzz came back. I think part of the changer must be just barely touching the metal plate underneath the cutout causing the hum--will check this out

I passed along a schematic of the 610ST chassis which is similiar to R-30-S to a friend who is an electrical engineer and very familiar with vintage stuff to
see if he can find any likely places where the B channel would be cut off from output since it is also being eliminated from the Aux jacks. If either of you know a common cause I would love to know ! thanks very much
Will

I am assuming that since you report the B channel to be very weak you must be listening in stereo. However, the R-30S only has the single channel power amp (though it has a stereo pre amp). I am still not clear how you're powering your "B" channel. Do you have the model 560 stereo companion with a 30-A amp or some other powered extension speaker? If you're using the 560 there's an input level adjustment on the 30-A you can use to match the levels right to left.

It sounds like you have your hum issue mostly figured out. You just need to fiddle with the changer's placement in the console until you figure out what's touching what or if it's cable routing, pinched tone arm leads or something like that. In my Contemporary II there's pretty good clearance between the bottom of the changer and that metal plate. Has the changer compartment in yours been modified in some way to accommodate the RC 210?

EDIT: Referring back to my previous post, this is a link to a post with some information on the "Liberty" Contemporary II. Is this what you have?

http://www.audiokarma.org/forums/showthread.php?t=359206

Sorry if my previous post was confusing. When I say the B channel is weak
all I mean is that no sound comes out of the unit (mono) when I have an input
RCA only plugged into the 'B' socket on the phono or aux . I don't have the 560 companion, unfortunately. My unit is not the one in the link although the finish is similiar. My dad bought this one in Wilmington,DE in '59. There's a couple nicks in the finish but the cloth is pristine and all in all the unit looks nice.


I think your comment about the stereo pre-amp makes it a good place to start.
I had replaced the fisher EF86's with some sovtek and did swap positions and there was no difference. Are those the only pre-amp tubes?

I made a cutout for the 210 but the depth of the space in the console may not be enough. That was the only change I made as far as that goes. It may be that I will need to get an rc121 mkii (just missed a restored one on ebay).
I looked through the hole where the cords come out of the cutout area and can
see that something is touching the metal. Not sure if I can jack the cutout up enough.

Anyone ever track down a schematic for the R-30-S?

thanks

My understanding of these quirky stereo pre amp/mono power amp Fisher receivers (R-30S, 610-ST and the sans tuner 510-ST) is that the B channel does not normally feed into the A channel power amp. It's possible that that the A and B phono inputs are summed when the selector is set to the mono phono setting but I'm not positive that is the case.

In order to definitively test the function of your B channel you will need to take the line level signal from the output labled AMPL on the rear panel (the one on the far right in the photo below) and connect it to a power amp. I guess you could connect the B channel output to the A channel AUX input although that would be running the signal through both the A and B channel pre amps which may distort if the initial input is too hot. Ideally, the B channel output would be run to it's own dedicated mono power amp (one with no pre amp) and a suitably remote speaker system in order give you proper stereo separation.

I'm thinking that the current TT has a magnetic cartridge, and the original had a ceramic. If it sounds weak and tinny in the phono RCA, then the amp is set up for a ceramic cartridge. One of two ways to go. 1.) get a ceramic cartridge, or 2.) get a phono preamp. Cost is about the same.

Larry

Larry -
thanks the original TT was a garrard rc121-mkii and I'm not sure what they
were sold with. This garrard 210 has a GE VR-22 and that I believe is a magnetic cart. Any suggestions for a replacement ?
thanks
Will

I have two RC-121 Mk. II's; one in my Contemporary II and one in a '59 Series 510. I acquired both with what I believe to be their original Sonotone 8T ceramic cartridges. My Sister-in-law's Custom Electra III with the 610-ST chassis also came with a Sonotone 8T on its RC-210. Brian and Larry's suggestions that your GE VR-22 cartridge's output might not be sufficient to drive the R-30S's amp is a strong possibility. I had assumed that cartridge was ceramic but I see it is a variable reluctance cartridge which is classed as magnetic.

Looking at the schematic below for the 610-ST (which I believe to be very similar to the R-30S,) I was surprised to see that all the inputs use the exact same pre amp circuits with NO RIAA or any other EQ other than the tone controls. Actually, I think that's a plus since it gives you two line level inputs. You'll probably get better results with a modern outboard phono preamp than with the comparatively primitive circuits that were used back in '59 anyway.

The EC92/6AB4 triodes in the 610 replace the EF86/6267 pentodes in the R-30S. The signal then passes through the tone control filter networks, the volume control, the front of section 3 in the selector switch and then to the respective halves of the ECC81/12AT7 before being fed to either the onboard ECC83/12AX7 driver/inverter and power tubes or the AMP B output.

The selector switch DOES, in fact, sum the A and B channels for the settings marked with the DOT and feeds the B channel signal to the AMP B output for the settings marked with the little triangle. I verified this on my Contemporary II.



Still looking forward to some photos.

Wow thank you so much for the detective work! What I understand you to say is that
the selector or ECC81/ECC83/EL84's route are involved with the weak B input signal ?
I'll snap a couple photos tonight with any luck!

If the signal is ONLY weak through the B channel input (when you have a mono source selected) then the EF86/6267 and half of the ECC81/12AT7 would be the only tubes (or parts of tubes) exclusively in the B channel.

The ECC83/12AX7 and the EL84's only come into play after the signals are summed. So if the signal sounds OK from the A channel input you can rule those out. There is also the possibility of dirty contacts in the selector switch as well as the tone control and volume pots. Not to mention all the resistors and caps (two of which are probably electrolytic) involved in the B channel preamp circuits.

EDIT: You swapped your EF86/6267 with no effect so that really leaves the ECC81/12AT7 as your only suspect tube. Replace it with a substitute that you know is good which doesn't necessarily mean a new one. (It's possible that an AK member in your area might be able to help you with that - but we'd need to know your location.) I would also clean all your switches and pots - even if you've all ready done that once - just to make sure. The next item would be to replace the electrolytic caps which should really be done anyway. Fortunately, there aren't too many on the R-30S.

Thanks a lot .
Yes I did swap the EF86 so I'll have to clean everything, though a friend
did replace all the electrolytic caps I'm almost certain. He replaced the capacitors and resistors that he said were old and prone to failure. One style was about an inch long brown canister shape the other type was what he said were commonly known as 'black beauties' , and he replaced all but one which was in an harder to access place. He would at least be able to help me test it or tell me how to test it at some point. Attached are some pictures. I took a stab at making a cut-out for the 210, and rushed a couple edges, front and side, but still have the original for the rc121. Last night I put the screws on the cutout through some rubber washers to jack up the player a half inch, and I'm still getting some buzz even with the player unhooked from wall and rca!! Sounds to me that a phone preamp may help with that as well, since it has a ground? only the ground was attached to the metal plate

Wow! Your Contemporary is in great cosmetic shape! I see yours has the "The Fisher/Stereophonic" badge in the upper right hand corner of the grill cloth. Mine is apparently missing. I had been wondering if mine was supposed to have one and, if so, where it was located on the '59s. Your photos answered that question for me - Thanks!

I hope Sam Cogley checks this thread to see that the cabinet code on your Contemporary II C-810 is "-P". His '58 Contemporary (I) also has that code. Unfortunately, we haven't been able to pin down exactly what wood/finish that refers to. What do you think? I figured yours was either teak or walnut but those should have the codes -T or -W, respectively. -P isn't listed in either the '58 or the '59 price list. The -P cabinet code denotes Fisher's "Provincial" consoles which normally came with either cherry or fruitwood veneers. Here is a bit of the discussion Sam and I had on this subject:

http://www.audiokarma.org/forums/showthread.php?p=4092043&highlight=contemporary#post4092043

The RC-210 looks quite correct in that setting even if it is giving you problems. I'd like to eventually find a Miracord for mine. Now I know I will also need a preamp.

My wife suggested Pecan immediately when I was wondering what it meant. She has an artist's eye for these things. The comment about the Provincial code though is duly noted. I'll post when I get a preamp and get the tubes tested and/or substituted.
When I first noted the channel problem I was making sure the tubes were seated ok and the ecc81 gave some static so maybe that socket is still dirty/oxidized --we'll see.

Always Check The Basics First

Contemporary said:

Hi-
I have a Contemporary II console that came without a changer so I bought a used/unrefurbished Garrard 210 for it that seemed to play fine on a modern
more powerful amplifier. When I hook it up to the console, though,
the sound is weak and there's a buzz coming through the speaker. I'd attached the ground wire to the sheet of metal under where the changer is because it looked like the old record player was grounded there. A tape player attached to the same inputs on the fisher amp sounds fine as the tubes, sockets and selectors have all been tested/replaced and cleaned respectively. Can anyone tell me where to ground the record changer or if this sounds like I need a new needle /cartridge since they look like original GE VR-22.
thanks
Will

Click to expand...

That table uses the same head shell and cable hookup as the Type A. The metal used by Garrard at these points develops a very NON-conductive coating over time. With all of mine it has actually been hard and black at the head shell wires, almost like carbon. It looks as if it belongs there, it does not.
Before I started chasing complicated problems I would remove the cartridge from the head shell and clean the leads with Brasso until they shine, wash with alcohol and treat with DeOxit. Clean the cartridge pins the same using Brasso and a Q-tip. Polish the contacts at the end of the head shell plug.
Underneath, where the PHONO leads plug in, scrub and polish them as well until they shine. Don't neglect the center RCA contact! I have had build up on this spot that was thick enough to need a little scraping with a pick. Gently re-tension them. Always exposed to the atmosphere and warm cool cycles for nearly 50 years. These RCAs are shallow and can be the source of many issues. Working, then moving the table or cables, then not working, is common. Stiff, high end cables can also prove a problem here. They can put undo stress on the little board and even interfere with the tables suspension (with the Type A anyway).
Polish and treat the ground wire's connecting lug in the same manner. Look at where it crimps onto the wire. If the strands have the black coating, trim back the ground lead and solder the lug back on if you can save it. If not then replace it obviously.
Spray and clean the contacts in the end of the tone arm several times with DeOxit, scrub the best you can (be gentle) and blow out with a little compressed air.
If you have a meter, plug the clean head shell back in your clean arm socket and with your PHONO cables attached, do a continuity check with your DVOM.
I have cured 99% of signal and hum problems on ancient Garrards with this type of head shell exactly this way.
You might be surprised.

Clean&Tight-
Thanks very much for the detailed cleaning instructions. Your experience is much appreciated. When I get a chance I'll do as you advise and post here the results!
Will

Hello-

Here's an update finally. Purchased a phono preamp (ART DJ PRE II (Phono Preamp with RIAA EQ) and this relieved the hum and buzzing as it has a ground on it as well as boosting the signal from the GE VR-22 so that the sound is really nice quality and much higher volume. Haven't gotten to the dead channel but did check underneath and the only black beauty cap that wasn't replaced is right by the selector for FM AM and so on! Will follow up when we get the channel. thanks for all the help
Will

Red: You can put a Sonotone cartridge on a Miracord and it'll play fine on the contemporary. As long as the mount fits the headshell, you'd be ok with a Ceramic cart on the Miracord.

Larry