Vintage JTM-50 - S/11295 - 1968 - what it it worth? How to rennovate (if at all)

pretty much due south

 

Ok, I am just East of Cambridge

 

I used to live in Sawston 10 years ago

 

Take it to Neil.

 

I have posted pics of the wiring and general amp hardware innards in my album:


https://www.marshallforum.com/media/users/redfish.29699/albums

20210408_111444 Copy by redfish posted Apr 8, 2021 at 11:54 AM

 

Very very nice indeed, so glad you haven't taken it to Marshall, that Brown Hunt's .05 cap would be thrown out first with no thought or hesitation grrrrr, my dads amp still has it in and it's still connected, round here they call it the Death cap PMSL........

 

Nice amp. I agree take it to Neil for a full inspection

Tubes were last changed in '77. Those 0.68 250V can't be original can they?

 

Ive never changed them .... and I brought the amp in the mid-late 70's

 

StingRay - can you explain to me what you mean by 'Those 0.68 250v' - I am new to all this - cheers - Red

Are they the big yellow 'cubes' wired in? Why would that be a surprise if they were original?

How do you know the tubes were last changed in '77? Is your middle name Poirot?

 

Indeed the yellow cube caps. They are the Philips successors to the mustard caps. But the varnish on the board looks untouched, so I have no clue (I'm surely not an expert like others here). The tubes mention Xf4 B7 so those are late tubes produced in '77. Since it also has a replaced transformer, it probably underwent a serious repair/maintenance before you bought it.

 

This amp looks converted to a 1987 lead spec. (V1B 2200pf).
I would leave the Philips chicklets, they are excellent caps! Perhaps replace with Mustards if a future sale for top dollar.
I really cannot tell effectively what the anomalies are, because of the insulating paint, as some are obvious. Slider bias - awesome mojo

 

Well I would certainly remove that death cap, it is call that because if it leaks and if in some situation you would be the ground, through your guitar or a microphone, well it could kill you..

 

Those chicklet caps are original. .

 

Ok
Original mid 68 lead amp
Replaced OT and fuses
That cap is not a death cap, just a snubber inch the HT. Hunts have a bad rep ( justified most will say) for failure so probably ideal to replace (internal short sends HT to ground - ie chassis)
It has Heath-Robinson screen resistors that needs to be done properly.
Really nice amp. If original OT worth over £4k (GBP) that is

 

What is OT?

 

output transformer
I actually have an original working one here.

 

Do any of you know about who would have signed the Test slip? (I was hoping to find Rosemary)

J MARSHALL SIGNATURE COMPARE by redfish posted Apr 8, 2021 at 11:58 AM

 

Looks like D Macloud or similar.
Not J Marshall.

 

Exactly.

Here's a Feb 69, those fuse holders look the same.

 

Here's S/11930