Original 68 JMP 50 Lead,

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neikeel
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Re: Original 68 JMP 50 Lead,

Post by neikeel » Thu Jun 16, 2016 3:08 pm

Rasputin1176 wrote:Any preferences on filter caps? I probably should replace them. Id rather have non original filter caps & be safer with original transformers.
Friday I should have all the info, detailed photos ect.
Thanks guys!!
The originals if they are quiet, not leaking physically (white powder on the vents) or electronically.

Don't rip them out just because. If they are duff or suspect they should go without question but if not I would keep them.
Neil

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Re: Original 68 JMP 50 Lead,

Post by Carbia » Fri Jun 17, 2016 5:53 am

Try to reform filter caps before swapping them.

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Re: Original 68 JMP 50 Lead,

Post by Rasputin1176 » Fri Jun 17, 2016 9:51 am

Yeah I agree with that & im still learning and hope to be doing more work myself but I don't know if I can test caps for leakage myself & I've only few techs here. 1 is way to crazy about taking out old parts and I never go anymore & other I have to see if he can test & reform....don't think many techs have testers to run caps full voltage levels and they should least have variac to reform but not my guy.

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Re: Original 68 JMP 50 Lead,

Post by Rasputin1176 » Fri Jun 17, 2016 2:35 pm

Image

Unfortunately it's a Bass model when specified as lead, I jumped on purchase because fully refundable & made sure it was told to be lead model 68.....
Now I can send back but, no jmp 50 68 leads I know of for sale in almost original condition. But I also don't want to really mod this original amp either even though I have nos parts to make it lead spec.

Damn, what to do. I say keep it as its killer amp but I will not be getting another for long long time, one major purchase this is it! I was more set on lead so either return and wait to find one, hopefully... Don't like this sounds good and I play Strat mostly.

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Re: Original 68 JMP 50 Lead,

Post by neikeel » Fri Jun 17, 2016 3:11 pm

If you play a strat that is the amp for you :hairband:
Neil

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Re: Original 68 JMP 50 Lead,

Post by Tazin » Fri Jun 17, 2016 3:23 pm

The board looks in good shape....Mainly just the two bias electrolytic caps changed out. I would say the amp is an early '69 (possibly Jan.-Feb.) rather than a '68. Does the serial number start with a "S/A" prefix? Additional pictures would help in determining if anything else has been changed.

EDIT: I think I seen this amp before....S/A10971? I believe it had a master volume installed on the back.

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Re: Original 68 JMP 50 Lead,

Post by Rasputin1176 » Fri Jun 17, 2016 4:15 pm

It's serial number has no letters. It prob had master vol at one point too because the hole is plugged where usually is one. Also the area around the small gold logo has extra holes for possible larger logo so I don't know what that would be? Possibly the head shell not original and just took better small shell box to put chassis in.

I think it's pretty bass heavy and do kinda miss ability to get more gain though even with strat and I dont' always use one but I do a lot.

Need to way it all out, it's expensive purchase and I have ability to return so not to bid deal.
Honestly haven't seen any lead 50 watts for sale in while though.

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Re: Original 68 JMP 50 Lead,

Post by Rasputin1176 » Fri Jun 17, 2016 4:28 pm

Tazin wrote:The board looks in good shape....Mainly just the two bias electrolytic caps changed out. I would say the amp is an early '69 (possibly Jan.-Feb.) rather than a '68. Does the serial number start with a "S/A" prefix? Additional pictures would help in determining if anything else has been changed.

EDIT: I think I seen this amp before....S/A10971? I believe it had a master volume installed on the back.

Damn!! That's the one! Where did you happen to see it.
I just don't like that store that sold it doesn't mention obvious stuff that they know takes away from value. I mean I don't care much. But this was sold as a Lead. I jumped before took a diff offer from another customer because aren't any others I've found as I mentioned & with possibility of return I figure what the hell?

It's great sounding amp, but I can only have one and lead is still my preference. Sucks, my luck I return this and have to wait while to find one & in what condition too. It's a gamble

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Re: Original 68 JMP 50 Lead,

Post by Tazin » Fri Jun 17, 2016 5:21 pm

I think I seen the amp last year sometime. When I seen it the following attributes were in place:
Cabinet was pretty beat up.
Had a huge 11-inch logo on the cabinet.
Both switches were replaced.
Both output sockets were replaced.
One 8K2/1w resistor was replaced with a 10K/1w.
Something weird about the OT...Endbells replaced and/or possible rewind???
Input jack(s) jumper wires were replaced...Used to be white, now pink.
The two bias caps were replaced.
The one top side filter cap was replaced (white or light gray colored one).
1K/5w screen resistors were fitted.

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Re: Original 68 JMP 50 Lead,

Post by Rasputin1176 » Fri Jun 17, 2016 7:58 pm

Damn!! That's quite a bit, I caught all but OT bells. I knew something up with logo because extra holes in the wood shell around small logo
Switch def not original, resistors & caps yep, & filter cap too.

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Re: Original 68 JMP 50 Lead,

Post by Rasputin1176 » Fri Jun 17, 2016 7:58 pm

I'm getting a refund likely, it's been offered as was not lead. May hold out for right amp

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Re: Original 68 JMP 50 Lead,

Post by Rasputin1176 » Fri Jun 17, 2016 8:04 pm

Image

Image

Image

Image

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Re: Original 68 JMP 50 Lead,

Post by Rasputin1176 » Fri Jun 17, 2016 8:10 pm

I doubt the transformers were rewound or replaced because unless they copied the old red dye (and they maybe can) it's not been removed.... Again not an expert.
Learning a lot. I've gone thru so much of the forum info past few months.

Thanks again!

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Re: Original 68 JMP 50 Lead,

Post by Tazin » Fri Jun 17, 2016 8:52 pm

Looks like someone did a little restoration work on the amp since I seen it.
They removed the master volume and plugged the hole.
Replaced the over sized logo with a correct repro.
They painted all the areas on the cabinet black where the tolex covering is missing.
Looks like they replaced both switches.
Also looks like they either replaced the OT or just replaced the endbells with more period correct ones.

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Re: Original 68 JMP 50 Lead,

Post by Rasputin1176 » Fri Jun 17, 2016 9:53 pm

Tazin wrote:Looks like someone did a little restoration work on the amp since I seen it.
They removed the master volume and plugged the hole.
Replaced the over sized logo with a correct repro.
They painted all the areas on the cabinet black where the tolex covering is missing.
Looks like they replaced both switches.
Also looks like they either replaced the OT or just replaced the endbells with more period correct ones.
Image


won't matter since returning, but for my own education; the solder joints for transformers look untouched. So yes bell covers could be replaced? But wouldn't it be likely original? Everything else yep, I noticed it as soon as got look at it.
Sorry no better pick when had chassis out but as soon as saw not lead I put it back anyway.
Just curious

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