1953 Seeburg HF100G

Hi,

Just purchased a HF100G, I'm having a problem with the carriage I was hoping you could lead me in the right direction. I was able to get it to play a record once but then it goes into this repeating mode. The carriage sits in one spot and picks the record up and then returns it. It does this over and over and over. I've tried cleaning some of the contacts, that's when I was able to get it to play once. HELP

John

After these have been taken out service the regular maintenance they need had stopped and they will dry up . You really need to take the mech out and clean it and re-oil the whole thing and restore the pinbank otherwise you might have all sorts of little problems . Someone will point you to a site to ''oil something'' to get it working .
The model G is a great sounding one when fixed up right .

Hi John,
What you will need to do, to fix this, is determine exactly what is causing this behavior. In order to do so, I contend that you must have a copy of the Service Manual, and, IMHO, a copy of my "Seeburg Mechanism Guide", should also be of help--( see "announcement" above, for "where to find--").
Once you have the Manual, locate the "Detent release lever" Hold down on this lever as the phono puts the record into play position. If it now plays the record without the detent coil being energized, allow it to play thru, and once again hold the lever down after it begins to put the record away. If it re-plays the record at that point, the problem is in the "Safety Plunger" section of the mechanism--or the record is warped, and can not "fall back" by itself. If the later is the case, do NOT attempt to pull the record out from the "front".
Let me know what you find, and we can "go on" from there--
Ron Rich

I did get a manual. I went through all of the contact adjustments. The main problem was in the pick-up and release contacts. After I did that adjustment it started to play the records. I still had trouble with the canceling of the pins. I adjusted the other contacts and everything worked just fine. I'm still having trouble with volume, I'm guessing that is the stylis issue. I hope to solve that problem but it seems that the sttlus' are as scarce as hens teeth. Any Help?

More scarcer-er--but what is your volume "issue" ? "Lotza stuff" in that jukebox that relates to volume, besides needles !Ron Rich

Did you see what that redhead cartridge went for on ebay today!!!!! $364, that's crazy. I bought a rebuilt MRA4-L6 with tubes and two needles from that guy I mentioned to you for that amount!!! He sounds like he has a lot of stuff. Do you know anyone near Finksburg, MD who's into jukes? I'd love to find a person in this area who has the skills and knowledge John seems to have. He's hard to communicate with though. I'm off to CA to see my daughters, so by the time I get back the amp should be here. If all goes well, yeah right, I hopefully will plug it in along with the needles and get full volume. If not I'm back to square one.

Just saw Ron's reply about the volume. I get sound out of the speakers when a record is playing. I have the amp cranked all the way up to get low-medium volume. When a record ends and is returned to the rack there is a loud pop from the speakers. This kind of leads me to believe that the amp might be working fine and the signal from the needle/cartridge is low or there is a problem in the circuitry that is causing the sound not to be amplified. When I saw the MRA4 amp on ebay I figured it was worth the cost for it, seeing as it was rebuilt. If I have to have the amp looked at then so be it, at least it's the correct one. Is there a way of checking the output of the needle and cartridge with a multimeter?

I'd love to be able to work on the amp. Could you lead me in the right direction to a circuitry for dummies book? I have some electronics experience but it's minimal.

"JP" there are three important elements in electronic design/repair:

1) Understanding basic theory.

2) Being able to read a schematic.

3) Being able to use the "tools of the trade". These include proper soldering technique along with the use of test meters and more advanced equipment.

For these old jukebox amps only a basic set of skills is required if all you desire to do is restore the unit to original operation.

As long as you can handle basic tools and are not 'ham fisted" -you'll be able to deal with it.

As for your amp situation, I suspect that the styli are the cause of low output.

Try plugging the RCA plug for that mech's pickup into any amp that has a magnetic phono input. You should have reasonably strong level, comparable to a standard pickup. The original 'spike" styli had very high output (and distortion) but the stereo comparable styli are somewhat lower and more inline with a normal pickup.

Next, if you have a volt meter that has a millivolt scale connect it directly to that same RCA plug and have a record playing. Again, the original styli would yield about 30 millivolts (really high) but a newer styli should get around 10 MV to at least adequately drive that amp.

Of course you can also connect a regular turntable w/magnetic pickup to the juke's input and check the results, you will need to connect that turntable's ground wire to the amp chassis to eliminate hum.

If signal voltages are within range then the amp becomes suspect. Given that you get a loud "pop" at trip off, I suspect the styli are the problem.

Rob/NYC

I don't know if there is a good beginner's book out there, but "Gameroom" magazine did publish a series of articles for beginners. The amp they work on in the series is a MRA3-L6 from a Seeburg C, but it should all be applicable to your amp. The articles don’t cover everything, but they do get you started understanding and learning how to troubleshoot jukebox tube amplifiers. Publication was a bit sporadic, so here’s the rundown on when they appeared:
1989 9 installments: April to Dec
1990 8 installments: Jan, March, April, May, June, Aug, Oct, Dec – none in Feb, July, Sept or Nov
1991 4 installments: Feb, May, August, Nov
1992 3 installments: Feb, June, Oct
1993 2 installments: Feb, May
If you're just trying to understand the amp, articles from the first few years are better. The later installments in the series go into test equipment like signal generators and oscilloscopes.
I think PDF’s of back issues are for sale through some of the coin-op vendors online.
Tim

Needles will not cause low volume . If a needle is bad you will simply get poor / not clear sound .

All of this type seeburgs i have restored all had low volume . The amp should get new capacitors . Those redhead cartridges are not all that good with loud volume . The replacement needles for them make the volume even lower . A good old black or gold head cartridge will double the volume . Also pull the volume limiter tube , that will help alot too .

Ken, we need to clear up some things before we give people misinformation.

1) The types and quality of styli do materially effect output level. The quantity of magnetic material in the stylus cantilever determines how much voltage is induced into the cart's stator coils. This relationship works inverse to tracking and overall sound quality. A high output stylus assembly will have a thicker cantilever in in order to induce more flux variation in the the coils. Lighter, thinner cantilevers track better allowing less stylus pressure and produce less needle 'chatter".

The Seeburg black and red carts are essentially two different creatures. On the black cart the stylus is merely an appendage to the armature. Here the stylus has no real effect on output level because it isn't the generating element.

On the red carts (and most other magnetics) the stylus and it's cantilever are in the flux field and do directly affect level and quality.

2) The "redhead" is listed as having 0.28-.30 mv. Years ago using a pair of mono "spikes" styli these were correct voltages for typical loud records. I measured and scoped them.

The black cart is actually lower source impedance than the red head: Approx 480 ohms-black vs. approx 1.7 k-ohms red. In this case the lower impedance produces less voltage into a given load. The variable is the generating element -the stylus on the red ones.

Finally, the gain structure of those old amps requires the AGC tube (6SK7 -6BJ6) to be in place in order to reduce level from a loud record and thus prevent distortion in the following stage (tone amp- cathode follower)

Analog AGC works by attenuation, it requires an excess of level being fed to it. With later angled styli in the red carts the output was materially lower and often the AGC wasn't fed enough excess level to have any effect.

Rob/NYC

I dont give ''mis-information'' I give the strait truth . If i must .... if you take a cartridge and needle that work good and put any needle on it the volume will be the same . If you change the small arm the needle is mounted to it can affect volume . I have done this hundreds of times . Please dont confuse people .

"Ken" -if you are going to give "advice" at least know what you are writing about.

Do some research and learn how a phono pickup works.

Then, do a little more reading and find out that a recent run of reproduction styli for Seeburg carts was made of faulty magnetic material and generated exceptionally low output.

The Swiss manufacturer was made aware of this and has taken the styli back with the statement that they will build an improved version 'soon".

To-date, no new styli have been issued.

Rob/NYC

Rob,
I fear that the "soon" has changed to "never"----
But I have "hopes" to find out this week ! Ron Rich

I've been busy with other things and had to put the 1953 Seeburg on the back burner. Wow you guys really go at it. I put a bad tube in the amp and popped the fuse so I took it and the MRA4-6 and the MRA3 to an electronic guy in Knoxville. I ended up bringing the whole back door and the speakers to him as he wasn't a Juke guy. Well he got the MRA3 working again, still low volume and the MRA4 has a bad output transformer!!!! Sheesh. So I just went out and pulled the tube as noted above, no difference, unfortunately my VOM meter is old and won't read the miliamps. I'm going to buy a nre digital one to work on these things.

So how do I tell if the output transformer is shorted or just bad? Do I have to unsolder all of the connections?