Rock-ola 448

Hello, everyone.

I'm new to the board and to the art of jukebox reviving. I acquired a non-functional 448 with high aspirations of a fully functional piece of history.

I am a little familiar with electronics and I feel O.K. with my skillzzz. I ordered the manuals/part list and should be arriving tomorrow. I have a multimeter and soldering iron at the ready.

Initial diagnosis: Dead.

Only one 2 lights work in the machine (1st digit, incorrect-press reset). There is no mechanical movement. Moving lever from Op to off to Scan produces zero reaction.

I will begin revitalization upon receipt of the manuals, but was hoping for some preliminary guidance from the community. What should I be expecting? How should my operation begin? Do I need to go out and get other diagnostic tools, oscilloscopes, etc?

I truly appreciate any advice.

-Carlos

Carlos,
I would not invest in a scope, unless you are going to tblshoot the computer--a good analog, and "digital" meter is handy-
I would start with a "fuse check"--be SURE they are "good" (use the analog meter ! ), the correct type, and size--then see what power is being supplied (or not) and go on from there-- Ron Rich

The 448 looks very similar to my 449 Carlos

As Ron Rich says I wouldnt worry about a scope unless its got AMP issues as the rest of it is very analogue and mechanical, start with all the various fuses dotted about, my 449 has had a number of little issues over the years and nearly all have been the result of grubby contacts, out of adjustment micro S/W's an just general wear causing drift on the mechanics.

The manual if its the similar to mine is quite good as it should go through the whole process from credit to record selection read in to read out and record placement on to the turntable to returning it to the carraige, although at times I find its not that obviouse to follow.

As you can see from my post I've got a current niggle thats causing me untold grief.

Be interesting to see how you get on with yours as I bet the majority is very similar to my 449 so if theres anything I can help with just shout, I'll keep an eye on this thread as well

Chris

Hey, Guys.

Thank you very much for your input. I just received the manuals and will begun full debug this week. I followed your suggestion this weekend and checked all fuses for continuity, and they are all in working order.

I will keep you posted!

Thanks again,

Carlos

Carlos,
When checking fuses, three things must be considered --
1. Fuses can look "good" and be "bad"--most of the time a meter must be used and the fuse must be out of the circuit.
2. Size and type of fuse is critical ! Should you find an good,"over-sized" fuse, used, it is most likely that this circuit has been "stressed" and it should be investigated-at least replace the fuse with a correct type. (A blown over-sized fuse is even worse here)
3. NEVER replace a fuse more then once ! Doing so just causes more damage, in most cases. The reason for "blowing" must be found, and corrected, prior to adding another fuse--
Ron Rich

Thanks, Ron.

I used my multimeter in continuity detection mode and all of them showed connection and beeped. I only checked the visible ones, (all ones within the caps you have to push and turn and the three on the bottom left inside the box). Are there any others I should check?

Also, I don't think I have a coin operator system. Am I in permanent "free" mode? There is nothing connected to the coin operator system at the bottom of the power supply box, and there is no coin switch were the coins drop. Also, when on, I am able to input the first digit (light for "first digit" comes on when pressing button).

I gave the manual a quick first glance and I don't even know where to go from here. First stop?

Thanks again,

-C

Carlos,
IMHO, the first thing one should do is "RTFM" ( Read The "Friendly" Manual) !
After that you should have some idea as to the power distribution, and you can follow it with your meter--
Also, you will know what terms are used for the items inside the phono, and if you get stuck, you can ask questions that all can understand--
Have fun reading--keep us informed
Ron Rich

As Ron says go through the manual stage by stage, its a bit weird (well mine is) but is quite good as it should go from inserting a coin and reading the credit (although it seems you may not have the cedit unit ? ) to writing the record in to playing it out.

There are a fair few fuses dotted about, theres three in the box with relay k6 which is located under the front panel for instance, thats if yours is similar to my 449 .

Keep us upto speed with how you get on

Chris

Hey, all.

Ok, here's the skinny.

C1 charges up immediately upon turning on the machine. 1st digit circuit works dandy.

When debugging for the 2nd, I noticed C6 is not charging. I am trying to figure out if it's C6, or Q1 that is the problem. In doing so, I placed my meter leads between emitter and collector, heard a relay pop into action, pressed another digit, the 2nd digit lite turned on, pressed a third digit, and the machine came to life!!! The carriage arm rotated with a nasty screech (need to oil up somewhere), I think I saw the current limit lamp come on as well, and then suddenly the whole thing died again.

I am unsure if I messed anything up in the process. 1st digit circuit still works fine. I have not figured out if Q1 is the culprit, or C6 is to blame. I think I tested the transistor with my MM in diode mode, but not sure if I did it right. Q1 has 30.5 voltage between base and collector and 29.7 between base and emitter when reversed after pressing 1st digit. Any advice? Should I just replace both?

Thanks! This is definitely more exciting than I anticipated.

-Carlos

Carlos,
Of course--replace both--
Ron Rich

I ran to Radio Shack (hereinafter RS) during lunch and was able to find an exact match to C6. however, the closes match to Q1 I found was PN2907. It's a PNP, max V ceo 40v, Vcmo 60v, and Vebo: 5v. Are these too low?

Thanks again, much appreciated.

Gang,

We replaced C6 and Q1, and sucess! We can now input three numbers and the show begins.

The search motor scans, and it is my guesstimating that it finds the values. The current limiting lamp comes in to stop the motor, and the whole thing dies.

I am reading the manual but not sure how/where to debug.

I am unsure of where to go from here. Any help is greatly appreciated.

Thank you!

Not sure if this is reaching anyone, but here's another update.

Hammer coil turns the correct selector level into play mode.

In sequence 16, the wobble plate solenoid appears to charge for only a second, the plate arm presses against the plate switch for a bit but then returns to its original position. In reading on, it appears the solenoid is supposed to remain energized and the contact should remain throughout play, so not sure what is wrong there.

Also, the switch may not be wired correctly. I've uploaded a picture. Is that correct? I followed the schematic, and it seems like the brown wire is supposed to connect to the yellow and green wire, which reaches the play control relay (when switched to operation mode). I don't think my switch is wired for that, but it also does not look tampered with in any way, so I may not be reading it correctly.

Again, any help is appreciated.

Thank you.

Hello Carlos,

I have not worked on Rock Ola jukeboxes for years, but the servce switch is the same type that is used on Rowe Ami and for that matter Fender Guitars.

Usually these switches switch AC voltages at one side of the switch and DC on the other side of the wafer switch (only on jukeboxes). Te switch is very dirty, I suggest that you clean it up with a pencil rubber (eraser) and check that the contacts are good and that the voltages are present.

Regards
Alan

Alan Hood
ami-man
UK