Newb Question (Rockola 1496)

Hello. I'm a pretty accomplished pinball guy, but to be honest I'm completely new to jukeboxes. A friend of mine has a 1962 Rockola 1496 120 selection "Empress" which has been in his family for many years. I've offered to help him bring it back to it's former glory. Right now mechanically it works perfectly. But it has a terrible HUM that makes it pretty unlistenable. Sad.

My idea is to drop a small tripath amplifier (I have one on hand already) into the machine so that he can enjoy his juke for a few months while we rebuild the amp on the workbench. We are likely to be slow since we both have kids and it can be hard to find time to work on stuff. Sounded like an excellent idea, but we tried cutting up a spare molex connector to convert the two pins of the input jack to a stereo plug and then using an alligator clip to convert the ground. No sound. Didn't work.

I assumed there was no sound b/c we needed a phono pre-amp connected, so I re-built my molex solution to plug into an "GE 23292 Stereo Turntable Pre-Amplifier." This actually worked... Sort of. There is a terrible hum still, and the quality of the music seems tinny and low-fi. Oddly, I can make a great deal of this hum go away by moving the input-to-molex thing around to various spots inside the cab. Also if I am touching the the alligator clip with my finger a great deal of the hum goes away.

I guess at this point I do not even know if my idea is fundamentally sound. It seems to me that the signal off the stylus should be the same as any other turntable signal at that we should be able to connect any amp to it and have success. We tried a home amplifier through the photo input and got the same feedback.

Just curious if somebody can give us some pointers so we can listen to the jukebox through a solid-state amp while we repair it's ancient tube amp cousin. Thanks in advance.

Dan

Dan,
I would guess that cable routing/grounding is the major problem you have encountered.
The hum in the original amp is probably "bad caps".
Also, with-out looking at the schematic, you may have some muting switch problems.
You definitely do not have "Molex" (Brand) plugs in that model, as they did not come on the market, until much later-
You most likely have A-MP Lock brand "nylon" plugs. For sure if the "pins" are "flat"-- (careful, they are made of un-obtanium !)
BTW--"Cap kits" containing all the caps are available at www.verntisdale.com
Ron Rich

Ron Rich wrote:You definitely do not have "Molex" (Brand) plugs in that model, as they did not come on the market, until much later

Hi Rich. Thanks for the response. You are correct on the molex. This connector looks a lot to me like a two-prong microphone jack. I have never seen anything quite like it. By trimming an old molex plug off I was able to get the two female connectors of the molex to line up, then I was using a an alligator for the ground. This approach is probably not going to work based on the amount of feedback we got. Oh well...

If I cut off an old RCA cable and connected that right up by the stylus would I have better luck, you think? Just curious. I really like this idea of being able to listen in the meantime while the amp work is underway, so I'm somewhat resolved to it at this point.

One other question. I've read on a few posts that you never want to solder to the cartridge, but this is what was done by the tech that worked on it last. I see it in the shop notes on the receipt from 2006. Is it possible damage was done by soldering but it took a couple years to manifest? Just trying to work out why the sound isn't as good as expected. I am not over there now or would post a pic, but it really looks to me that soldering is the only option on this cartridge, so not sure if this is a red herring.

BTW, thanks for the verntisdale address. Looks like that cap kit is a must in the near future. Really appreciate that there is a board like this! Thanks so much. I have learned a great deal on a pinball board which is similar.

Dan

Dan,
I would expect any "TECH" working on phonographs, of any kind to know--or soon learn-- that one does not "solder to" the posts of ANY cartridge.
I would further suspect that if this has been done, the cartridge has been changed. If so, is it the correct type for that model ? ( You might check with Vern, as he probably will know which type was used--if not, see the "where to find" list above)---I do not recall--also, if you have the parts book, it may say-- As for listining to it on your amp--can't tell you--you will need to figure out what type cart you have, output voltage, and match an amp to it--

Thanks Ron! Your information is very helpful to our quest. I'll keep you posted.

Dan

The stereo R-O's of that era came with a ceramic cart that use what was called an "airplane" shaped stylus. The replacement is an Astatic N-43. But really, don't bother, any ceramic from anywhere near that far back will be shot.

Also, if you are trying to use a newer amp remember that a ceramic will overload a magnetic preamp -which is what any quality receiver or amp will have. You can try the "aux" or other line level type input but these will generally be too low in impedance, this will cause reactance with a ceramic cart and kill whatever bass it might have.

I had a 1496 and used a Pickering V-15 now known as Stanton 400 series. You'll need a small outboard preamp for use with original amp. The tone arm is crude and I did add a counterweight and eliminated the dumb finger spring.

Rob/NYC

Great info in that post, thanks. Couple nights ago we actually got it going. We ordered a new cartridge. Just got a PFANSTIEHL P-132D off ebay for $15 shipped.

I cut up an old RCA cable and crimped on d-sub connector pins. Then it's going into a $20 GE 23292 Stereo Turntable Pre-Amplifier and then a $20 Lepai Tripath TA2020 Class-t Hi-Fi Audio Amplifier.

The result is we're rocking out and can now take our time re-capping the original amp! Many thanks.

Dan