Marshall JCM 800 Combo

This One Goes To 11

This amp came in with a few issues. The first was a red plating power tube. The others were general noise and control response issues. Both power tubes tested weak. All other tubes tested good.

The EL84’s were replaced along with the broken cathode resistor that fried them. The electrolytic caps in the power supply were leaky and also replaced. This got the amp working but there were still noise issues. Found that two of the potentiometers had been changed to non-originals and didn’t seat in the board correctly. This caused the board to become microphonic affecting the controls around them.

Replaced these with original parts and reflowed all the solder connections on the pots and jacks on the front panel. This solved the microphonic problem.

  • Type: Tube 

  • Number of Channels: Single channel 

  • Total Power: 20W (5W setting) 

  • Speaker Size: 1 x 10" Celestion V-type Speaker 

  • Preamp Tubes: 3 x 12AX7 

  • Power Tubes: 2 x EL34 

  • EQ: 3-band EQ 

  • Inputs: 2 x 1/4" (high, low) 

  • Outputs: 1 x 1/4" (16 ohm internal), 2 x 1/4" (single 8 ohm or 2 x 16 ohm), 2 x /14" (single 4 ohm or 2 x 8 ohm), 1 x 1/4" (DI out) 

  • Effects Loop: Yes 

  • Power Source: Standard IEC AC cable 

  • Height: 18.1"

  • Width: 20.1"

  • Depth: 10"

  • Weight: 32 lbs.