Connecting wires to new cartridge on Rock-Ola 454

[Darol]

I just picked this fairly nice jute box up a week ago and all that was under the arm was three wires hanging down. A red, a black and what appears to be a white one. Nothing else. So, I ordered a new cartridge, a needle and 4 connectors. Is there anyone here that can tell me how to connect which wires to the cartridge? The back of the cartridge has an L on one peg, an R on the opposite one and between the top 2 there's a +.

[jukeboxmarty]

Without accessing a machine and checking to verify....

I would connect the red wire to either the R or L terminal, the white wire to the remaining R or L terminal, then the black wire bridged to the remaining two terminals.

-Marty

[Darol]

Thank you Marty. Out of curiosity, if I didn't get a solid connection at the cartridge, would that possibly cause the left speakers to have a buzz and very little volume or should I be looking somewhere else? I've tried other speakers and I get the same results.

[jukeboxmarty]

Yes, possibly. But you should also rule out the amplifier.

Try switching the input to the amplifier to see if the problem shifts from one channel to the other. I'm pretty sure this can be accomplished by flipping the input connector 180 degrees. If the problem switches channels, it's the cartridge wiring (or cartridge). If the problem remains on the same channel I'd start looking at the amp.

-Marty

[Darol]

In my manual, I see the, "Front amp assembly chassis". At the bottom left, it has two 6 pin plugs. I'm assuming that one of these is what you're talking about. The left is V-15386. The right is V-7005. I have pictures of this, but can't figure out how to post them here and I do hate to mess with the wrong one and possibly creating myself yet another headache.

[jukenorman]

No, he doesn't mean either of these (The left is V-15386. The right is V-7005), he means the little three pin phono input over on the bottom right hand side, directly below "Input Level Control" R1L. I think maybe it has a slight offset on the pins but you should be able to connect it enough to get a test; don't force it though.

Norman.

[Darol]

OK. Well, I accomplished the 180 twist and the sound remained on the same channel. Hmmm. What is entailed in looking into the amp?

[jukeboxmarty]

Troubleshooting an amplifier requires a fair amount of technical prowess and an overall understanding of the amp's architecture.

Amplifier issues can be difficult to track down with a hit and miss approach.

If you think you can tackle the job we can entertain specific technical questions, but you may consider sending the amp to someone who has experience with Rock-Ola amplifiers.

[Darol]

I have a couple multi-function testers here and wouldn't hesitate to try a few tests with some guidance from the forum. If I need other electrical equipment, I'll get it. We can give it a shot anyway. I am in a VERY remote area in northern California so you guys are my go to at this point and would very much appreciate the help. I do have the complete manual with all the detailed schematics.

[jukeboxmarty]

Most noise issues would be hard to track down utilizing a multi-meter.

Many buzz or hum issues are due to ripples in the power supply due to failed filter capacitors, or lack of grounding somewhere along the line.

In your case, the power supply section seems to be functioning fairly well, as one channel appears to be functioning normally.

The lack of volume in one channel suggests a failure of one or more of the amplifier's stages.

It could also be as simple as a failed volume control potentiometer or a bad connection in the volume control plug (P2).

Sept 28, 2023 18:03:27 GMT jukeboxmarty said:

If you think you can tackle the job we can entertain specific technical questions...

Here's a totally random example of a specific technical question (which doesn't apply to your case):

I'm only measuring +27vdc at the base of the driver transistor at Q6LR, is that acceptable?

If you can formulate specific questions after your own investigation, we can certainly try to answer them.

Maybe someone else has a simple suggestion or two?

[Darol]

OK. I finally believe that I found the culprit for the lack of sound from the left channel. Inside the amplifier box there are two 3x5 circuit cards. Again, I had very little, crackly sounds from the left channel. I switched the cards and now the problem is on the right channel. Does anyone know where a guy might find one of these cards? I have pictures, but I haven't a clue on how to attach them here. From what I read, it's confusing. This is a 1973-4 Rock-Ola 454.

[jukenorman]

Hi Darol,
You're going to have to provide more information than that! Can you identify the item from the schematic or the part list? Or does the board itself have any identifier? The posting of pictures has been covered many times, there are "sticky" posts above - but one more time, use Postimages and copy the hotlink for forums.

Norman.

[Darol]

I'll try this. On the back of the card, there is this.

49079
Ck-P SE-0

If that doesn't work, I'll try the schematics.

[jukenorman]

49079 does look like a Rock-Ola part number. To complicate thinga a bit, the 454 had amp 48350-A fitted and I have mainly have info for the 48350-1A which is identical as far I as can see but may have different part numbers. Is it the pre-amp board, does it have an 8 pin integrated circuit (IC) on it?

Norman.

[Darol]

Yes, it has 8 pins. I found the part number in the manual. It's a Driver Board,

Part # 49125-A