CW Guitar Audio

CW Guitar Audio Professional repair/mod service of guitar amplifiers and all guitar electronics in central Ohio

2010 Diezel VH4 retube/service. First time in 3.5 years I got a little time to work on my own gear. This one just got ...
05/13/2026

2010 Diezel VH4 retube/service. First time in 3.5 years I got a little time to work on my own gear. This one just got a quad of JJ KT77 tubes, bias, and a dusting off. Experimented over a few years with different power tubes in it and settled back on the 77’s after trying everything else. If you focus in on the preamp you’ll see that every VH4 except for a few are built on a board that doesn’t accommodate all the components as if each is a prototype although they are all the same unmodified amp. Just an idiosyncrasy as all other models are built on a fully designed PCB.

Vox AC15C1 came in with no output. Found 1 power tube to be intermittently shorting from vibration so a new matched pai...
05/11/2026

Vox AC15C1 came in with no output. Found 1 power tube to be intermittently shorting from vibration so a new matched pair of EL84’s was installed. Still no output so further digging found that one IC chip in the reverb/buffer circuit was shorted as well. While in it, the screen resistors were upgraded in both value and wattage to make the power tubes last longer, keep the resistors from becoming damaged from a power tube short, and suspended from the board to keep the board from being damaged in the event of a failure while also dissipating heat properly.

Mesa Mark V had broken power tube bases stuck in the sockets from being installed incorrectly and a non-functioning rev...
05/10/2026

Mesa Mark V had broken power tube bases stuck in the sockets from being installed incorrectly and a non-functioning reverb. Got the tube base pieces removed, new tubes installed, checked everything over, and found the reverb fault. The reverb failure was caused by a transistor in the switching/muting circuit. With some skill, was able to replace it through a preamp tube socket opening rather than removing the whole board and front panel controls which could lead to another hour of labor.

PRS S2 Standard 22 in for a pickup swap and mod. Installed customer supplied Seymour Duncan JB/Jazz set. By customer r...
05/08/2026

PRS S2 Standard 22 in for a pickup swap and mod. Installed customer supplied Seymour Duncan JB/Jazz set. By customer request, I then installed a push/pull CTS volume pot with a switchable stock treble bleed(180pF) and pull option(Kinman treble bleed) for further retention of highs as the volume control is rolled down.

A couple custom-made studio switchers I made for a local recording studio. The customer needed a solution for switching...
05/08/2026

A couple custom-made studio switchers I made for a local recording studio. The customer needed a solution for switching mic inputs to interfaces and preamps so they would not need to manually plug/unplug at their patch-bay each time. There are no commercially available options to achieve what he needed without buying multiple other units chained together. For their API mic pre’s lacking a line level input, a switchable -20dB attenuator was added to the outputs of all “mix” outputs. They required 10 channels in a 1U rack which as you can see was a squeeze but I got it done.

Fender Blues Jr. in for a bias mod to get the power tube bias to a safe level. This keeps the tube board from overheati...
05/08/2026

Fender Blues Jr. in for a bias mod to get the power tube bias to a safe level. This keeps the tube board from overheating leading to damage of traces over time and longer power tube life. Checked the rest of the amp over and gave it a clean bill of health

Sears Silvertone 1472 in for a checkup. Installed a missing rectifier tube, a recap including all electrolytic capacito...
05/08/2026

Sears Silvertone 1472 in for a checkup. Installed a missing rectifier tube, a recap including all electrolytic capacitors and replaced all other high voltage capacitors in the amp known to go leaky for age and indeed were in this case. A 3 prong grounded cord was installed, grounded direct to the chassis, death cap removed, and mains rewired properly. Some of the pots were severely noisy so as always all controls cleaned.

Markbass CMD 102P combo was cutting out intermittently then had progressed to blowing the mains fuse. Found a screw and...
05/08/2026

Markbass CMD 102P combo was cutting out intermittently then had progressed to blowing the mains fuse. Found a screw and washer used to hold the main PCB in place rolling around which was causing the intermittent output issue until it killed the amp entirely. The remainder of the screws were finger tight. Although Markbass and their USA support were very responsive, they refuse to provide any service info or tech notes to aid in troubleshooting. These amps are made with switching power supplies and class D power amps making repair very complicated even with schematics. This one was beyond component-level repair due to power supply damage. They do offer replacement circuit boards and in this case the customer decided to proceed with that option brining the total out to almost the price of a working used amp. Something to be cautious of if ever considering any amp utilizing switching supplies and running class D. I’ve been getting a lot more inquiries across brands for these type of issues so it’s buyer beware. A well-built amp weighs a lot more but you can keep it running forever.

Orange Dual Terror was damaged in shipping breaking all toggle switches and 2 pots. So all switches were replaced then ...
04/28/2026

Orange Dual Terror was damaged in shipping breaking all toggle switches and 2 pots. So all switches were replaced then the board was removed to replace the broken pots.

1968 Fender Bandmaster “drip edge” service complete. Came in with a loud hum and non-functional tremolo. Was worked on...
04/27/2026

1968 Fender Bandmaster “drip edge” service complete. Came in with a loud hum and non-functional tremolo. Was worked on previously by another tech who didn’t resolve the issue(58 year old electrolytic capacitors, cooked power tubes, broken solder joints). So the amp received a full recap of all electrolytic capacitors, new plate resistors, grid stoppers, screen resistors, rebuilt bias circuit, new rectifier diodes, power supply resistors, new power tubes, correct bias, a new power cord correctly wired, and corrected grounding. New filter caps not pictured as I got too excited to start on the next amp.

1961 Gibson Les Paul had issues of portions of the volume control being dead. Found incorrect wiring, a signal wire tou...
04/24/2026

1961 Gibson Les Paul had issues of portions of the volume control being dead. Found incorrect wiring, a signal wire touching a pot case and pieces of solder and wire strands touching the jack tip to ground. Rewired and cleaned contacts.

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1042 Solomon Square
Delaware, OH
43015

Telephone

+17408191458

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