Blown fuse in Rockola 408

While in the middle of a record (It was playing fine) the turntable stopped. The 1.6 amp fuse had blown (by the way a 3 mdl fuse was installed. I replaced the fuse and it blew immediately. I manually advanced the gripper motor to replace the record. I then replaced the fuse again and it is has played a dozen records without a hitch. The motor for the gripper was a lot harder to turn than the basket motor.
Any suggestions or did I just have a hickup?

There are reasons why fuses blow.
Obviously something is drawing too much current, but across a computer screen one can only guess.
Best to consult the service manual, and troubleshoot with schematics to find the cause, and remedy it.
Only the rated fuse should be used for replacement.
Anything else is asking for trouble.

Thanks, I just ordered some MDL 1.6 A FUSES. i PURCHASED THE 408 FROM A Frien WHO SAID HE HAS HAD IF FOR 30 YEARS. THE 3 AMP FUSE HAS PROBABLY BEEN IN IT ALL THAT TIME SINCE HE CLAIMS HE NEVER HAD IT SERVICED. i GUESS HE WAS LUCKY.

David R

David R wrote:Thanks, I just ordered some MDL 1.6 A FUSES. i PURCHASED THE 408 FROM A Frien WHO SAID HE HAS HAD IF FOR 30 YEARS. THE 3 AMP FUSE HAS PROBABLY BEEN IN IT ALL THAT TIME SINCE HE CLAIMS HE NEVER HAD IT SERVICED. i GUESS HE WAS LUCKY.

David R

If it's never been serviced, then it's now way past due for service.
Discontinue using it until such service is performed.
The blown fuse is a hint of impending trouble.
Otherwise, parts will self-destruct and increase the costs needed for proper repairs.

David R (not Rockola?) be sure to check -all- fuse values.

If that blown fuse is the Low-vDC it indicates the gripper motor has either shorted turns in it's armature or binding in the gearbox. Both are common in R-O.

You mentioned that the shaft on the gripper motor is hard to turn. When I encountered this is was the result (I believe) of the large gear in the gearbox swelling slightly. The only practical solution was to -slightly tilt the motor shell by loosening the two screws that hold the motor together and placing the edge of a washer (approx 1/32) to cant the two halves thus moving the armature worm slightly away from the gear and relieve the pressure. Somewhat "Geppetto" -but nothing else works if that is the problem.

BTW: Tf you blew a 3 a fuse in what is supposed to be 1.6 -consider yourself lucky that no other damage was done. When those motors are running as-new they draw about .5 to .6A.

Rob/NYC

At the time both fuses blew neither the gripper or the basket motor were running. A record was at mid play without any other action happening within the jukebox. I appreciate the heads up with the possible motor binding problem. As earlier stated I'm a newbie at this sort of thing but have oiled, lubricated, cleaned, replaced a ballast and the basket belt. I'll pull the gripper motor. There was a marked difference in the ease that the shafts turned between the gripper and basket motors.

Thanks

David R

David R wrote:At the time both fuses blew neither the gripper or the basket motor were running. A record was at mid play without any other action happening within the jukebox. I appreciate the heads up with the possible motor binding problem. As earlier stated I'm a newbie at this sort of thing but have oiled, lubricated, cleaned, replaced a ballast and the basket belt. I'll pull the gripper motor. There was a marked difference in the ease that the shafts turned between the gripper and basket motors.

Thanks

David R

Before pulling anything, find out the lines that those fuses feed, first.
Should be in the manual / schematics.
You can't compare motor "resistance" when they don't operate the same mech.

Hi David,
I would, since it blew both fuses while "nothing" should have been drawing power from that circuit, suspect some intermittent power supply problems. Therefore I would change whatever rectifier, and cap is the source. See the Service/parts manual(s)
On the motors--the gripper motor works much "harder" then the basket motor, as there is much more to do--You might note that they are two different motors--aside from the end gear difference, you can always use a gripper motor to run the basket (gear change is necessary), but you should never use a basket motor to run the gripper-- Gripper motors, regardless of which brand, can be ID'ed by the (20 wt.) oil hole drilled in the area of the front bearing. Ron Rich

Ron, David there is actually more involved in replacing-subbing gripper vs. magazine motors, at least in my experience.

On the mech using the old style grey motors there are two and four wire types. The 2's are gripper and 4 wire (field coil) are magazine. The triad of mounting holes are slightly different in that the top hole is slightly closer to the gearbox and won't line up.

(Gepetto alert) I had to use a magazine motor as sub for gripper in a 1458 that I was selling in Dec 1989. I ran another two wires for the field and added a relay connected to the armature ckt to switch it. I had to cut off the loop at the top mounting hole and use a washer to allow it to be mounted in the same hole as the correct motor.

At any rate, when the gripper motor is unmounted the shaft should turn easily if all is well in the gearbox.

David, if that blown fuse is associated with the amplifier --do not use the machine-- till you get the amp rebuilt.

Rob

The tubes were still glowing when the fuses were blown. There are also 3 & 5 amp fuse holders, one of which I assume runs the amp. I have a cap replacement set but due to other commitments I planned on rebuilding the amp this winter when I had the time. I'm pretty amazed at the quality of sound as it is. The gentleman I purchased it from kept it upstairs in a fair environment and even thought he had a very good looking wife, he said he danced mainly with his dog to the music. He's quite a character.

dmr

David,
I am willing to bet, that if you looked at the area, just on top of, or under the fuse that blew, you would see the word "Mechanism" silk-screened there -- An "amplifier fuse" should have no relationship to the turntable, or gripper motors. You SHOULD, before plugging that phono to the wall, check ALL fuses, for correct type/size !!!! Ron Rich

As a follow up to my blown fuse. The amplifier unit has a 1 amp slo blo fuse in it's side. The power unit contains 4 fuses. one is marked as for fluor Lights - a std. 3 amp fuse. One other 3 amp std. fuse (unmarked). One 1.6 amp slo blo (unmarked) and one 3 amp slo blo fuse also unmarked as to usage. The 1 amp slo blo had a 2 amp slo blo fuse in place and the 1.6 amp slo blo had a 3 amp slo blo fuse in place. The last one was the one that blew twice.
I have since received and replaced all fuses with the marked sizes and types. We've played at least 150-200 records since without incident.
Many thanks for your comments and assistance.

David R

And.... "THE 3 AMP FUSE HAS PROBABLY BEEN IN IT ALL THAT TIME SINCE HE CLAIMS HE NEVER HAD IT SERVICED. i GUESS HE WAS LUCKY."

Let us know when the bomb hits, k?