Difference in preamps in Wurli 200?

[alexdecker]

Hey

Just got a new Wurli home, and when opened up, I could see some differences in the preamps, compared to another one I have at home. I am not much of an electronics wizard, so thought I would post a pic here and see if anyone could make something of it? I attached the pics to this post...

- Alex

[sean]

They look the same to me.  The second one has been re-capped, and may have new transistors. 

The first one (with the silver Mallory caps, and the hum shield removed) looks mostly factory original to me.  Notice the glue to secure the big caps during soldering, the cute red dresses on the transistor leads.  All the carbon-film resistors look out of place to me - they are too shiny and new looking, and they look too stout, as if they are half-Watt.  But why in the world would anyone replace ALL the resistors, so I guess these are factory original.

The second amp has clearly had the electrolytic capacitors replaced.  Instead of ordering close replacements with axial leads, they just used what they had on hand (caps with radial leads) and stretched the wires to fit the original drilled holes in the board.  This is pretty common practice in repair situations, and not completly unreasonable in new production.  On this board, you can tell it was repair work, because of the glue residue marks on the board.  (The cap on the far right is replaced with a unit with axial leads.)  I can't clearly tell from the photo if the transistors look factory original.  It looks like a lot of thermal grease smudged all around, you might be able to tell if there were other transistors installed previously. The resistors on this board look much more normal to me (quarter-Watt, sourced from a number of suppliers).

Both boards show pretty impressive heating around the 200Ω resistor on the far right.

Sean