Uploaded December 2025 | Updated September 2026, 1 week ago
A customer brought me this Marshall Haze MHZ40C tube combo guitar amp for repair. He said he had it re-tubed recently and another tech did some work on it and he said it didn't sound right and also it was cutting out. He could play for about 30 minutes and at some point the sound would cut out completely while the amp stayed on. In this video, we'll explore the possible reasons for the issue and eventually fix it...I THINK!?
Tomlov Digital Microscope: amzn.to/3XUYVwP
Fesley Les Paul Copy: amzn.to/4pIsa2c
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0:00 Owner describes problems with his Marshall Haze 40
1:32 Amp on the bench - first inspection
9:31 What Marshall Got Wrong and RIGHT with the Haze 40
13:06 Dummy Load and Rebias the Output Tubes
25:26 Reflowing sockets
26:30 Testing with a Guitar - Tone Demo
32:18 FAILURE and More TROUBLESHOOTING
38:30 Pulling and inspecting the main PCB board
48:36 Marshall Haze 40 Schematic Analysis
53:37 Parts Replacement
55:18 FINAL THOUGHTS on the Marshall Haze 40 - Is it worth repairing?
♠RECOMMENDED BOOKS
-RCA TUBE MANUAL amzn.to/2GOBVqS
-Designing Tube Preamps for Guitar and Bass: amzn.to/2DK5tmt
-DESIGN AND CONSTRUCTION OF TUBE AMPLIFIERS: amzn.to/2HSNMne
#guitar #electronics #repair
A customer brought me this Marshall Haze MHZ40C tube combo guitar amp for repair. He said he had it re-tubed recently and another tech did some work on it and he said it didn't sound right and also it was cutting out. He could play for about 30 minutes and at some point the sound would cut out completely while the amp stayed on. In this video, we'll explore the possible reasons for the issue and eventually fix it...I THINK!?
Tomlov Digital Microscope: amzn.to/3XUYVwP
Fesley Les Paul Copy: amzn.to/4pIsa2c
*SHOW YOUR SUPPORT*
1: Become a Member on Locals: theguitologist.locals.com
2: Donate via Paypal: paypal.me/guitologist?locale.x=en_US
3: Buy Merch: bit.ly/GuitologistMerch
4: Send in Viewer Mail. (Contact Me for details at electrictoothsyndrome@gmail.com)
5: Purchase an ad! (Rate sheets available upon request at email above.)
6: Buy something from a sponsor and tell them I sent you.
7: Stand in the middle of the street naked screaming "LONG LIVE THE GUITOLOGIST!" Then when the cops arrive, tell them about my channel.
8: SUBSCRIBE TO THE FIXOLOGIST CHANNEL: youtube.com/@fixologist1
0:00 Owner describes problems with his Marshall Haze 40
1:32 Amp on the bench - first inspection
9:31 What Marshall Got Wrong and RIGHT with the Haze 40
13:06 Dummy Load and Rebias the Output Tubes
25:26 Reflowing sockets
26:30 Testing with a Guitar - Tone Demo
32:18 FAILURE and More TROUBLESHOOTING
38:30 Pulling and inspecting the main PCB board
48:36 Marshall Haze 40 Schematic Analysis
53:37 Parts Replacement
55:18 FINAL THOUGHTS on the Marshall Haze 40 - Is it worth repairing?
♠RECOMMENDED BOOKS
-RCA TUBE MANUAL amzn.to/2GOBVqS
-Designing Tube Preamps for Guitar and Bass: amzn.to/2DK5tmt
-DESIGN AND CONSTRUCTION OF TUBE AMPLIFIERS: amzn.to/2HSNMne
#guitar #electronics #repair
