UPDATE-1983 JCM 800 2203 gut shot- normal or modded?

  • Thread starter Thread starter tonesfoyobones
  • Start date Start date
Here’s a quick pic of caps top side

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RedPlated said:
Yep your right. These are one positive and one negative rather than the typical dual can. Maybe these are 100uF single cans vs a paralleled 50uF dual can. They really should be dual cans as the voltage stability increases when done that way.

What's the value of the cans? And voltage ratings?
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My 74 came stock with Daly single can caps which was the reason one started to leak due to overheating/over voltage. I did replace it with properly rated modern single cans though.
 
Those look to be 350uf and 385v. Seems a bit off in both departments.
 
Get those caps out and replace with ARS 50/50uF @ 500v.

Those caps are underrated in voltage. They are 175uF as they are in series. That's super stiff on the screens especially.

Good call on Chubbs. I think he found your issue.
 
glpg80 said:
I really hate JJ and F&T caps, personally. It’s good that it’s been recapped though.

Jeremy and I both swear by ARS both tonally and in reliability.

You should be proud of that amp. I prefer early 80’s JCM800s. Good score 👍
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I can definitely hear the goodness in it but can tell that my low end feels off
it’s not a fair comparison but my Hopkins just nails it in every way
the 83 seems like it will be pretty aggressive when right
 
RedPlated said:
Get those caps out and replace with ARS 50/50uF @ 500v.

Those caps are underrated in voltage. They are 175uF as they are in series. That's super stiff on the screens especially.
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That makes sense. I’ll order some and see when I can have them changed out. My tech isn’t asking on any new work right now due to overload. Ugh
 
RedPlated said:
Get those caps out and replace with ARS 50/50uF @ 500v.

Those caps are underrated in voltage. They are 175uF as they are in series. That's super stiff on the screens especially.

Good call on Chubbs. I think he found your issue.
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Well in series the cap value half’s and the voltage rating doubles, so they’re 175uF total at 775V total. That’s more than what I run in my Enmity mod by far capacitance wise for screens or B+

OP that amp likely just needs properly recapped.
 
glpg80 said:
Well in series the cap value half’s and the voltage rating doubles, so they’re 175uF total at 775V total. That’s more than what I run in my Enmity mod by far capacitance wise for screens or B+

OP that amp likely just needs properly recapped.
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Yep 350/2 in series for 175uF.

The reason there are dual cans in these amps is because of the voltage. One 50/50uF can paralleled equals 100uF total and then in series, back at 50uF at 1000v.
 
Where else can order some ARS caps? Valestorm sold out
 
Ordered!
thanks to everyone who helped get this figured out today. That’s why I love this forum. You guys know your shit! Greatly appreciated
I’ll do a follow up after the cap job. Should be a bout a week or so
 
FourT6and2 said:
I believe that MIGHT be from ARS themselves. When I bought ARS caps a few years ago, I bought them on eBay direct from ARS. For some reason they don't sell them direct from their website. Only on eBay. I dunno... they haven't figured out web stores yet lol.
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RedPlated said:
For future reference, you can call ARS direct and order over the phone. That's how I do it.
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Over the phone is how I do it too. I prefer to use a size you can’t get online and have to order direct.
 
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