Seeburg USC1 with TSA10 Amp Treble but no bass

My Question:
Be for I get into checking all the wiring, is it possible for the amp to be bad if I am getting plenty of Treble from the horns but nothing from the woofers.
Thanks Lenard

Of course it is possible that the amp is "bad" -but bad connections or open speaker voice coils are more likely.

With the unit playing:

1) Check for any sound at all from the woofers.

2) Turn volume down and remove one pickup plug. Turn volume back up. if you now have at least some bass, the wiring to the pickup is faulty. try this with both channels.

3) Check that there are 3 wires connected to the speaker connections on the front of the amp. The black wire must be on one of the common (ground) screws.

4) Try connecting an external speaker to the terminals on the amp front. use the "16" watt and "GD" ground terminals. At this point if you have good bass from the external speaker the next step is to check all connections to the speakers and the crossover box.

As a practical matter, this machine is 43-44 years old and has seen heavy commercial service followed by years of neglect. The electronics --must-- be rebuilt for safe, reliable operation.

Rob/NYC

Rob, Thank you for the reply.

I will check everything on your list. I am also going to recap the amp soon. I have ordered a new cap kit and plan on doing this with in the next week or two. I also am new to Vinyl Jukes. I do have a couple of Cd jukes and really want to get a 45 Juke.

Thanks Lenard

Lenard, you may enjoy this:

http://oldnewyork.tumblr.com/post/99820 ... -a-halston

In it's habitat.

NYC was a big Seeburg town till the mid-late '80s when Rowe product took over. There were two main factors; one was that although Seeburg had the first ( and IMO best sounding) CD box (1986) their Manhattan distributor, Albert Simon Co. went out of business in 1988 and Seeburg was on too shaky financial ground to sustain their products by then.

The "Bandshell" was by far the best looking machine that Seeburg built in the console era. It screamed "late '60s -early '70's" In 1968 my father a prominent art dealer and his business partner renovated a townhouse near Central Park as gallery and office space. It was all chrome and glass. That jukebox would have been perfectly at home there.

The few that I worked on in the late '80s had SHP amps in them instead of the last TSA series as built.

Rob

Hi Lenard,
To add to Rob's great advice--
There are a couple more things to do/check--.
Check that one of "Rob's Geppeto friends" has not dis-connected the single wires from the bass switch going to the PC boards ( Yep, done seent dis happen, more the once ! ). Check that the internal speakers are connected ( with-OUT any other wires "hanging loose", or connected to outside speakers), to the highest taps on the front of the amp (40 watt, if I recall correctly ?) Clean ALL tone controls, AND the volume control--I suggest using a plastic safe, non residue solvent, then, when dry, following that using Deoxit-5, and "working it in".
One more thing I can think of--one of "Rob's friends"--work ?--be sure a mouse or two has not eaten either the wires, or speaker cones (OK--probably NOT, one of his "friends").
And BTW, to Rob--Seeburg strongly recommended a "SHP amp", NOT be used in a USC, especially the -2, due to the fact that it WOULD overheat ! Ron Rich

Rob, I checked and there is no sound at the woofer at all, I Removed both pickups 1 at a time and it made no difference at all. I then hooked up and external woofer to the ground and the 16 watt terminal. I still have nothing only the Horns are working at this time.

Ron, Thanks for chiming in with a few more things to check. I will check these and get back to you all as soon as I can.
I would also like to get a copy of you book. where can I find it .

Thanks Lenard

Hi Lenard,
You are welcome--Seeburg Mechanism Guide, is available directly from me--just PM me--
Ron

Ok, if the external speaker had only treble that pretty much points to the amp.

These amps have a few problem areas:

Edge connectors on the boards and especially the feed-through stakes that couple the agc board to the two preamps under them. All boards should be washed and blown dry with particular attention to the edge terminals. When washing them work the bias pot on each board to allow whatever soap you are using to scrub the rotating contact.

Important: If the bias pot develops a dead spot at any point in rotation it will kill the output transistor. When powering up after rebuild, place the amp's 120volt input in series with a 25-40 watt light bulb to act as a current limiter. I generally replace the bias pots with a fixed resistor of around 100 ohms. During initial power-up with bulb tap and slightly wiggle the boards and check for any bursts of bright light from the bulb. these would indicate poor edge connectors on one or both preamp boards. If necessary you can tighten the connections by using a tiny screwdriver to --slightly-- close the contacts gap in the connector.

Given the symptoms the amp has I suggest a total capacitor replacement of all caps on all three boards along with the large caps on the chassis pan. The small brown ceramic caps may be OK, but the electrolytic caps are most important here.

It is a good idea to test the volume control for proper resistance from the high side to ground and the two taps to ground. All values on both sections should be within 10-20% of each other. Those old volume pots are the usual cause of unbalanced channels after an amp is rebuilt. On a properly operating amp the two channels should be well balanced with the balance control at dead center (I often remove the balance pot).

Cleaning and replacement of capacitors is essential for electronics this age followed by careful power-up and readings of the main voltages from the power supply.

Rob/NYC

Rob,
Dis-agree here--
I can't recall seeing a TSA with the three PCB's in it that had "edge connector problems", except a couple that had obviously been wet. In those cases, the "L-shaped" A-MP edge connector had been "attacked", and needed total replacement. Also, I have never thought to "pinch" the other type connectors. I have seen them fail, or be intermittent, but have always been able to polish the "studs", then use a chemical cleaner, on the female sides--On the "Bias pot"--If the seal is still intact, I usually do no touch it, unless I change outputs-- If I do, I clean it with Deoxit-5,
and have never experienced a failure.
I have seen many failures of the "single post connectors" used on that amp to connect the tone switches--the females MUST be clean and tight !
---And--last, but not least--How do you "clean a cap." ??
Ron Rich

Thanks for all the info guys, I checked the single wire to the cpu and its hooked up, I checked the wires in the lower cabinet all are good and hooked up not eaten by mice, I also cleaned all tone controls and volume control. I still only have treble. I am at this point thinking I need to get a new amp. Any suggestions where I can find one in working order with out getting robbed. I think I can rebuild it but I have never done anything like that before, I would hate to waste my time and money and it not work when I am done.
Thanks Lenard

Hi Lenard,
Try one more thing--
Remove the red-blue and black wires from the amp--find a known good "D cell"(flashlight battery). Touch the black wire to the bottom of the cell, and "tap" he red one on top of the cell--You SHOULD hear a "pop" from the bass speakers. Then if you do or don't, hold the black wire on the bottom, and tap the blue wire on the top of the cell--once again you should hear a pop. If you don't hear it on one, but you do on the other, one speaker is 'blown'--If you don't hear it on both red, and blue wires, either the black wire is cut/broken somewhere, or both speakers are blown.
A "new" amp that is compatible with that system is not available--if your speakers are good, I suggest that you have your amp re-built.
Ron Rich

Lenard, at this point all I can give as advice is that if you don't feel competent to repair the amp yourself, sending it to someone is still the best option as opposed to trying to buy a "new" old one.

If you go that route be sure to remove and send the volume control assembly. inquire whether they adequately test the amp with speakers and pickup along with what sort of guarantee they offer.

I'm sorry that I can't offer any idea as to price for a rebuilder's service. In 31 years of operating and collecting, I've always done this work myself.

Check the "where to find" posts at the head of this site. That should have listings of reputable technicians

Good luck and keep us informed.

Rob

Ron, I tried the D cell battery and only heard the pop sound from the tweeter horns (both sides) and not from the woofers. I think I am going to remove the woofers from the cabinet and test the same way eliminating the wires all together. If I don't hear any pop at least I know it the woofers for sure..

That's what I thought you would find--yes,remove them and use a couple of "wires" to test them( or a meter--they should read about 4 ohms)--I think it's about 50/50 that they are bad, or the wiring is "messed up" somewhere going to them--Let us know-- Ron Rich

Ok, Well I think I narrowed it down to both woofers being blown. I unplugged the woofers in the cabinet from the plug next to the mech. I then Ohm each woofer from there and have open circuits on both no ohm reading at all. I then played a record to see if I was getting a reading at the plug where the woofer plug in at and to my surprise I am getting a signal down at that plug. I am not sure what the spec or reading should be but as the record was playing it was jumping as if a signal for the woofer was being called for.

Any thoughts on this would be appreciated.

Thanks, Lenard