Rowe Ami Jal amp issue

Hi everybody

I having another go at repairing my Rowe Ami Jal
I have my second Juke a Jel up and running with a good quality sound
The issue I have with the Jal is the loud popping when the mute relay kicks out (opens) before playing the record and kick in (closes) at the end of the record...I have clean the relay contacts with writing paper but still the same..the power amp is the R2620..I have proved the fault onto the amp because I swapped the amps over between my 2 jukes and the fault moves with the amp..
Could it be a capacitor issue or am I barking up the wrong tree.
Any help pointing me in the correct direction would be appreciated

Regards Mark...

Essex..UK

Mark, for reasons that made sense only to the amp's designer, Rowe-AMI switches the B+ between records as part of the mute-squelch function.

This means that a large B+ shift occurs at each switching point.

Suggestion:

- Make sure you replace all coupling capacitors. Be sure to include the 0.047 across the B+ contacts on the relay.

-Be sure there is good chassis ground between amp and preamp. This is critical in keeping any amount of DC from being grounded via the audio grounds vs. the proper chassis ground returns.

-Check the 3K-ohm resistor across the B+ contacts.

Not related to your question; I add 100 ohm resistors in-series with the G2 of each 7868 tube. This was normal later and acts as a fuse to limit current when-if the G2-G1 short occurs. It can save your output trans. Adding a 10 ohm ½w to each plate will further protect the trans. 7868 Tubes were made to be highly efficient. This requires close spacing of the grid structures and makes them more prone to shorts.

Do you have a schematic? Power amp is here: http://www.verntisdale.com/AMIschem.htm

Rob-NYC

Hi Mark just had the same problem on somebody's jal the other day, I'm not saying the reason for his jal popping at start and end of record play is the same as yours, it also had an annoying hum when not in play, but the reason for his problem was I suspect two reasons. the first was that he had connected his volume control to the pre amp back to front, also the jukebox had no mute function, apparently been like this for long time, mute switch was a bit kaput no amount of cleaning etc would cure the mute problem. well it did for a couple of try's then kept returning. had to replace one of the contacts, the problem is now cured, but like I said it could be a number of things like Rob correctly said. If you have any spares lying around for a JEL or JAL, the contacts on the latch relay on the button bank will do the job on the mute switch as long as your hands don't shake like mine and put the spacers back as they come out. Hope this might help, Harry

Thanks Harry and Rob

I have the schematic in my manual ..shame I can't understand it..ha,ha
I stripped my machine down so many times I know where and why things work and sometimes don't but faulting on a component level and reading the schematic I find a little challenging..
I replaced all the caps on a spare power amp 2620 (like for like..supplied by bill bickers) only to discover when I connected it all up the mute relay was duff..power was going in to it but it would operate..this one I will repair at a later date when I get hold of a new mute relay
So I was hoping to get this one up and running without a full recap
Is the 3k ohm resistor your speaking of the ceramic one under the 5u4gb?

Mark