|
|
Post by jollyjon on Nov 29, 2021 17:06:17 GMT
I have a 480 model in which the main filter electrolytic caps in the amplifier need replacing but unlike all other caps in the amp that have the values printed on them, the main filter caps just have a plain metal like cover with no identification printed on them. I can't afford a schematic so wondering if anyone has the manual if they would be able to provide me the value of the 2 main caps. I figure since I get 47VAC in that the caps must be at least 50V each (or maybe 80V to be safe) but don't know the uF value. I think it likely be at least 4700uf to 10000uF but it would be easy to identify with a schematic. They are 41 years old so should have been replaced 20 years ago but I had it in storage for last 16 years and it surprised me at the immensely loud distorted hum it produced when I took it out and turned it on - it was so loud I thought the speakers would explode if I left it powered on for more then 2 seconds. I think there are other similar models that use the same amp - such as the 484. Any help is much appre3ciated but please indicate if the value is from your manual or just an estimation based on similar size amplifiers.
|
|
|
|
Post by jukenorman on Nov 29, 2021 21:20:40 GMT
|
|
|
|
Post by jollyjon on Nov 30, 2021 7:43:28 GMT
Thanks Norm, that's great. I did happen to find schematics and parts list in photos on google earlier today and found what I was looking for but the link you provided has everything so great if any problem arises in future. I was going to replace both C71 and C72 as they are 41 years old and electrolytic caps are supposed to last about 20 years so they should be replaced and likely get rid of the immense loud noise it plays as so as the jukebox is turned on. I might have to replace the much smaller caps might I'll check first and listen after I replace the 2 main ones. What I do need is a recommendation of what should be used as the caps are listed in catalog as 3000uF -10% + 100% 50V. That may have been the case 40 odd years ago but today the closest is 3300uF. I have concern about the capacitance tolerance being +100%. Usually caps might be about 10% or even 20% both ways - and +, but its weird it's +100% and -10%. Could it peak at some stage with volume and need to be 6000uF and 3000uF is just a usual playing power level. Maybe I should go with a 4700uF with a 20% tolerance then that would cover 3760uF to 5640uF. The part C71 and 72 is listed as -10 and +100 so that's about 2700uF to 6000uF but that might be a typo. I'm no tech expert or crafty with electronics so it be great if someone is aware what is typically replaced in this 40 year old amplifiers. I don't wish to replace yet with a standard 3000uF if it needs to be able to have upto a 100 increase in uF and I might damage other parts of amplifier or it may still produced a mild hum of a sort instead of the very very loud distorted hum if the uF rating is not precise. Any guidance appreciated
|
|
|
|
Post by jukenorman on Nov 30, 2021 9:08:43 GMT
I suspect that you are "overthinking" the issue - the 3300uF will be fine!
Norman.
|
|
