Seeburg KD200 - crackling and popping through the speakers

Hi guys,

A newbie here, and have just joined these forums. So please forgive me if this question or topic has been asked before.

Ok....I have a couple of KD200's and I am slowly working through some issues with them.

One issue at the moment which is kinda bothering me is that when the Mech scans either left or right (mainly right as you look at it) on both Jukes, I get crackling and popping through the speakers.

One Juke is fitted with it's original valve amp and circuit cards etc, and the other is a bit of a frankenstein fitted with a SS Amp.
Any advice would be appreciated.

Cheers
Glenn

Glenn, some points here:

The K-L has the (mediocre) preamp in the mech and the muting is done there via contacts on both stacks. Poor ground in those contacts is one place to look. Run your finger along the stylus while the mech is scanning and listen for it through the speakers. The placement of the preamp in the mech instead of the amp aggravated the noise problem due to the high voltage pulses of the readout being conducted in close proximity to it.

Another area to check is the timing of the detent switch and alignment of the Tormat. If you look carefully you will see sparking when misalignment causes the R-O voltage to be present before the plunger is actually on the Tormat rivet.

I've read suggestions that placing a 10K-ohm resistor in-series with the grid of the first tube (I guess that would be V171 in this schematic http://www.verntisdale.com/schem/kd-200.jpg) would help, but I've always found that cleaning up the ground connections and Readout timing fixed that problem.

FWIW: I've always bypassed that preamp and used a better quality outboard instead.

As for the "Frankenstein" -you definitely have my interest here, some pic's will help. Anything could be going-on when hackers have been at-play.

Rob-NYC

Thanks for the reply Rob,
I'm pretty new to this whole game...and I would need to do some reading so I don't look like an idiot. However, I will have a shot at a bit of a reply.

I'm going to give your suggestion of running my finger along the Stylus a try tonight when I get home. I can definately hear the muting taking place between record changes though.

As far as the Jukes go. One Juke is pretty original in a sense, and the other is all over the shop, bits and pieces from many a Juke....this one is the Frankenstein (even has VL buttons and drum).

The only deviation on the original Juke that I can see is that it has been fitted with I think a 222 tone arm and Stereo cart. The wires have been paralleled and fed into the preamp. Then from there is business as usual with the signal heading down to the TCU. I have bypassed the AVC because when I got the Juke (a couple of months ago) it had hardly any volume, so I went straight into the TCU. On the list of course is to look at the AVC....but I'm hoping to find a complete set of cards soon that I can get serviced, and then swap out...so its slipped down the list.

The Frankenstein juke is fitted with a Pickering 345 and no preamp. The wires from the cart are joined straight to the wires heading down below, and then into the SS Amp. This Juke has no AVC, no TCU, and no PAU. So the plan is to use the swapped out cards from the other juke (when that happens) to test and play, and hopefully get it back on the road to original fitment.

So I guess your suggestion of V171 in the AVC won't help me at the minute with either machine.

On the alignment of the Tormat. OK....when I got the Frankenstein, it was not selecting the correct B sides...it was always one high, like instead of B1 it would play D1 and so on. Not sure whether this was the correct fix or not, but I ended up moving the TMU a fraction to the right which sorted the problem. I noticed at the time that there was sparking along the tormat rivets as the contact block ran along. Not overly bad, and not on every rivet, but it was there. I just assumed that this amount of sparking was par for the course on this type of operation. So if I read you correctly there should be no sparking at all???

Sorry, no idea on what the detent switch is all about....though I know it's in the Mech somewhere. Yes....I need to hit the books again.

Which ground connections are you referring to? I'm also interested in the preamp bypass you are reffering too.

Thanks again Rob

Glenn, the first step is to obtain a service manual for that model. You have two high-value machines, but they were also a one-off and somewhat troublesome due to the printed boards. I have a K in commercial service but i converted it to use later electronics. For home use the boards are probably Ok -if- some precautions and modifications are undertaken.

On the alignment of the Tormat. OK....when I got the Frankenstein, it was not selecting the correct B sides...it was always one high, like instead of B1 it would play D1 and so on. Not sure whether this was the correct fix or not, but I ended up moving the TMU a fraction to the right which sorted the problem. I noticed at the time that there was sparking along the tormat rivets as the contact block ran along. Not overly bad, and not on every rivet, but it was there. I just assumed that this amount of sparking was par for the course on this type of operation. So if I read you correctly there should be no sparking at all???

Sorry, no idea on what the detent switch is all about....though I know it's in the Mech somewhere. Yes....I need to hit the books again.

Ideally there should be no sparking at all. Sparks build up carbon deposits which foul the rivets and lead to erratic readout. The sparks also throw a lot of electrical noise which leaks into the sound system -especially if there is even slightly inadequate muting.

To align the Tormat; bring the mech to slot A1 and let it fully detent into play mode. Check readout plunger at the rear (closest to you when facing the back of the mech). It should be slightly (about 1/3) onto the following rivet, that will be C1.

Once that is set and locked the detent switch which is located just rear of the motor may be touched-up. The way i've long done it is to loosen the locknut around the "grub" screw (a screw w/out a head) just enough to allow it to be turned. I then turn it counter-clockwise approx ½ turn and start the mech scanning. If i don't see any sparking I turn it c-c a little more till I do see sparking and then back clockwise till sparking stops. That is not the "book method" but I've found that with worn mechs there can be some unevenness with the length of the readout pulse application and this will make sure that all points along the Tormat get adequate pulse duration.

Again though, a manual is essential if you haven't dealt with Seeburgs of this era before.

Rob-NYC

Hi Glen,
Just a little to add to what Rob posted--
If you do not have it, you need the Service Manual PACKAGE, that goes with the models K/L. ( see above post, as to where to purchase) !
On the contacts that ride the TMU--before "adjusting" be sure that there is silver on top of the pins, and that they are not "gouged out" --they should be flat to slightly domed, on top. The Detent switch, also should be examined prior to adjustment. It must be free of burrs/pits, and ,of course, must still have silver on the contact points.
Audio popping while scanning on the K/L models is much more subject to happen if, the pre-amp shield, and/or the "hum shield" for the whole inner door is missing. Also check that the ground screw is tight on the mechanism front , and the 5 amp fuse has NOT been "bypassed". Also,you probably should remove the TMU and check the condition of the center grounding bar--if the silver is worn off, you can flip it over ( MAY need to re-drill mounting holes). Be sure all Phillips screws are tight--do not over-tighten--just snug them up-- Ron Rich

Hi gentlemen...Rob and Ron,

Firstly thanks so much for the continued replies.

OK....I did purchase a couple of manuals from Victory Glass, namely their R-277 and the R-225. However, I must admit that despite being somewhat useful, they do leave probably more questions than answers. They are not real flash when it comes to technical descriptions and/or detailed pics of components, aka the mech etc. I have made contact with a gentleman over here (Erwin) who has offered me a copy of your book Ron, and I do need to still chase that one up. Hopefully, it contains some detailed pics of the mech and it components.

Alright....moving on here. I must admit that I didn't get the chance to check on the stylus during scan over the weekend....sorry, one thing lead to another with lifes other distractions lol.

OK....so no sparking is good...happy with that. I did notice the procedure for aligning the TMU in one of those manuals, and both your replies have clarified that. So I guess I will be looking at that alignment now. When I was at the TMU on the Frankenstein machine, I also noticed that the contacts on the block are flat, and bordering on concave (pitted). I guess they will need replacing, is there a good source for these...or is it a matter of having to solder and reshape? Just on the contact block ( I cant recall reading it as yet), but is there adjustment procedure for its up/down alignment? I have also noticed some wear on the center grounding bar, and I will also remove the TMU to see how bad it is....I guess no silver at all is a sign to turn it over.

I'm not sure what this detent switch is all about. But by the sounds of it, it's at the back of the Mech, and I assume that the record rack needs to come out. Furthermore, is the detent switch...or its associated components (levers etc etc) the last thing you hear before the stylus hits the record? The reason I ask is that on this original juke, I get this real loud click...like something is about to break.....sends shivers down my spine. Yeah everything is lubed....well i'm pretty sure it is.....again the manuals aint the best here either.

I will check on the pre-amp shield....I guess it should be attached to one of the pins on the pre-amp. On the Frankenstein with it's missing pre-amp....who knows where that is attached, so i will need to look for that. The other end of the shield should be attached at the plug on the TCU of this original juke, and I guess the outer conductor of the RCA plug on this Frankenstein juke.

Ron, would you be able to give me a 'grid square' on where the ground screw and fuse is located on the front of the mech? Also the hum ground on the door??

Rob, with the boards, you mention precautions and modifications? What are your thoughts on these new reproed boards? They would have to be a marked improvement?

Finally, can either of you gentleman recommend somebody who can rebuild a KD Mech? I have one sitting in OH, that I wouldn't mind rebuilt before I have it shipped over.

Many thanks again

Just on the contact block ( I cant recall reading it as yet), but is there adjustment procedure for its up/down alignment?

Two Phillips screws that hold the block on the mech casting. The holes are oblong and allow vertical adjustment. Don -not- push it "way up". Only about a 1/16th of an inch overtravel is needed when you pull down on the block.

I'm not sure what this detent switch is all about

You don't remove anything more than the mech cover. The switch is right next to the motor. It is what applies the readout pulse at each rivet on the Tormat;

As for the contact plate under the tormat, this is how I've dealt with it since the early 1990's:
https://www.flippers.com/Seeburg-tormat.html

Oddly, I was looking for a pic of the detent switch and this article comes up...well they credited me and it now saves another explanation of a frequent topic.

Furthermore, is the detent switch...or its associated components (levers etc etc) the last thing you hear before the stylus hits the record?

Nope. that is the popularity meter advancing.

Preamp: If the preamp is bypassed it should be "floating" -that is the shield must -not- touch anything on the mech or chassis till it hits the input. otherwise a hum loop will result.

Rob, with the boards, you mention precautions and modifications? What are your thoughts on these new reproed boards?

Since my first encounter with those boards was getting an "L" for Christmas 1969 and my last dealing with them (after two more L's) was the K in early 1998 none of the repro boards were available and I just examined and usually washed and reused the originals. I "inherited" a box of those boards from the Albert Simon co when they closed here in 1988. I only needed two and the rest were sold to my friend Bill.

Shine a light through them and look for blackening of the phenolic -especially in the high voltage and high current areas around the tube sockets and the edge connectors.

One of the big problems was resistance buildup at power stage's edge connector. This was where the (rare) fires occurred. Some people removed the edge connector and soldered the wires directly to the board. I just made sure the fingers and edge pads were shiny clean, then added a film of solder to each finger and pad and sweated them together one-at-a-time.

I'd try that first. If the boards look bad or show weird problems when powered, you can just buy the unpopulated repro boards and transfer the new caps, etc onto them. I may be the son of an art dealer...but I am also cheap:-).

Rob