Mark V Reverb Issue / PCB Parts Placement?

[funkmasterron]

I am troubleshooting a buddy's Mark V 25 which is working, but with no reverb.
I've tried swapping reverb tanks to another Mesa amp, and the tank in the Mark V is fine (and the other tank works, but not in the Mark V either).

I am looking at this schematic (https://el34world.com/charts/Schematics/files/Mesa_boogie/Mesaboogiemark_v.pdf), especially page 5.
The tube sockets are easy to probe, and I see the input signal go through the preamp sections fine, but the signal doesn't make it into V4A pin 1.
I am aware of the JFETs on the reverb circuit going bad, and am thinking the issue is likely J175M2.
But I'm having a hard time finding it on the actual PCB.
I see various J174 JFETs on the PCB (not J175), but none that say M2, D, or E.

Does anyone have a parts placement diagram (or blank PCB) with the reference designators on it?
Or can you circle where the J174/J175 JFETs in the reverb circuit are on this picture?

TIA!

https://drive.google.com/file/d/1e8nBE_KU67n9ZLiBAmjfWEkJWfvnvox1/view?usp=sharing
https://drive.google.com/file/d/1e3P2O4gytW-F1rtDW_SIdDxe_xVuS_tm/view?usp=sharing

 

[rarebitusa]

If I'm not mistaken that is the V:90 schematic from 2009. Have to assume the V:25 would surely be different in many respects including schematic reference designators.

 

[funkmasterron]

Correct, that is a schematic for a different Mark V amp, and the closest thing I could find online.
Any ideas on where to find a Mark V 25W amp head schematic?

 

[rarebitusa]

Not aware of where one for the V:25 would be. FWIW on my V:90 J175D is sitting right next to V5B.

 

[batflash]

Curious if you made any progress on your reverb issue. I'm having problems on my Mark V 35. Getting output on the tank, but nothing is going in.


Thanks,

J