Mark V reverb stopped working...

[rickcruz1]

I finally looked at a schematic of the Mark V, which I found here...so glad I registered on this forum. Mesa was not as helpful to me as they were to Andre.

In case anyone wants to know, it's J175MS, next to pin 3 of V4. Clip the zip tie and move the grey wire out of harm's reach, and be careful not to burn the side of the switching orange relay. I obtained the replacement JFET (J175-D216Z) from Mouser.com. It was $0.51.
As Mesa stated to me (over and over), "there are lethal voltages inside", so a qualified Mesa person should be the one to do the job.

One day I may share the email with you...it was kind of funny to me, but they DID remain gracious, although a bit condescending. I totally understood their position, having manufactured amps myself.

 

[MarkV User]

One day I may share the email with you...it was kind of funny to me, but they DID remain gracious, although a bit condescending. I totally understood their position, having manufactured amps myself.

They were also rude to me when I asked about whether there was an engineering change related to the low voltage diodes that failed in my amp. I just wanted to know if it was a bad batch or parts or an engineering mistake. In the end I thought it might have been a little of both and I did substitute a different diode based on my own best judgement because they wouldn't give me any information.

The episode was upsetting because customer support at Mesa should have wanted to forward that question to engineering. If I were in their place I would facilitate communication with customers and also document design and manufacturing errors. If they worked like that I would buy more of their stuff.

I bought my Mark V new, like a sucker. Freakin' Kurt Cobain didn't even buy his Mesa gear new. That studio 22 preamp he played supposedly came used from an ad in the LA Weekly. Never again. I love my Mark V to a degree, but it didn't sound good the way it came when I bought it new years ago, and it was my only guitar amp for these past years, until I bought a different amp and realized what I had been missing.

I'm less experienced with amplifiers than most people here. What I did to make things better with the Mark V was:

-Changed the defective 1N4007 diodes in the low voltage supply. This fixed the foot switch, which had never worked right, and fixed some glitches that would happen during normal use of the amp.

-Got a bias meter so I could evaluate tube changes, and switched the mesa 6L6 tubes for EL34s and an inner pair or EL84s on adapter sockets. This warmed up the amp and got rid of some unpleasant high frequency distortion.

Next step will be to try to make the preamp tube changes similar to what has worked for others, and then debug inside the amp to isolate the source of the unpleasant high frequency resonance (before the power section). It should be possible to get great sound from this amp with 6L6 tubes also.

I think the Mark V is a kind of wonderful and ideal amplifier design with some mistakes. It is only poor business practices by Mesa that have messed up the experience and convinced me not to buy or recommend their products. It is such a contrast with how wonderful Bogner seems to be with his customers. There are so many glowing stories from people who have dealt with that company. I would have been so happy if when I called for information they would have just said, "Yeah, we kind of messed things up with that amp. Here are a list of things you can do to make it better."

 

[user 41014]

They were also rude to me when I asked about whether there was an engineering change related to the low voltage diodes that failed in my amp. I just wanted to know if it was a bad batch or parts or an engineering mistake. In the end I thought it might have been a little of both and I did substitute a different diode based on my own best judgement because they wouldn't give me any information.

The episode was upsetting because customer support at Mesa should have wanted to forward that question to engineering. If I were in their place I would facilitate communication with customers and also document design and manufacturing errors. If they worked like that I would buy more of their stuff.

I bought my Mark V new, like a sucker. Freakin' Kurt Cobain didn't even buy his Mesa gear new. That studio 22 preamp he played supposedly came used from an ad in the LA Weekly. Never again. I love my Mark V to a degree, but it didn't sound good the way it came when I bought it new years ago, and it was my only guitar amp for these past years, until I bought a different amp and realized what I had been missing.

I'm less experienced with amplifiers than most people here. What I did to make things better with the Mark V was:

-Changed the defective 1N4007 diodes in the low voltage supply. This fixed the foot switch, which had never worked right, and fixed some glitches that would happen during normal use of the amp.

-Got a bias meter so I could evaluate tube changes, and switched the mesa 6L6 tubes for EL34s and an inner pair or EL84s on adapter sockets. This warmed up the amp and got rid of some unpleasant high frequency distortion.

Next step will be to try to make the preamp tube changes similar to what has worked for others, and then debug inside the amp to isolate the source of the unpleasant high frequency resonance (before the power section). It should be possible to get great sound from this amp with 6L6 tubes also.

I think the Mark V is a kind of wonderful and ideal amplifier design with some mistakes. It is only poor business practices by Mesa that have messed up the experience and convinced me not to buy or recommend their products. It is such a contrast with how wonderful Bogner seems to be with his customers. There are so many glowing stories from people who have dealt with that company. I would have been so happy if when I called for information they would have just said, "Yeah, we kind of messed things up with that amp. Here are a list of things you can do to make it better."

There are 2 people in particular in customer service that don't understand what customer service is. One seems to have got better at the job description.

I won't call them out but when you get a response from Kris my experience is that you are dealing with a professional in every aspect.

One of the ******* (no offence to *******) wanted me to send proof that I owned mesa gear before he would allow me to order tacks for replacing corner leather for a few cabs. John at mesa hollywood walked me back from the cliff of wanting to dump 30 amps and as many speakers. I did start paring down.

I can only assume those 2 are part of the family since one in particular is horrible in a customer facing role.

 

[MarkV User]

Thank you for the insight Mayhem. I have some sympathy for people who work in customer service roles on a highly technical product like this one, because they have become so visible. And still, the kind of company I like to deal with figures out how to get their systems right. If you're like me you only call these folks once in a great while, and you take responsibility for and full ownership of the things you buy. What someone like me wants is technical information, open communication, and the perspective of someone who hears a lot of customer experiences.

In customer service they hear all the stories and it is valuable when they are helpful. I called the company that makes my large rotary compressor for example and the tech there ran through all the strengths and weaknesses of the machine with me and what was likely to fail and when, and what different patterns of use would probably do to that. He wasn't cagey about sharing details or concerned with hiding the weaknesses of the machine. And he didn't try to tell me I couldn't do the work myself. It made me glad I had bought the product.

Since Mesa doesn't have it maybe we should compile a document that describes some of the theory of operation and describes common Mark V mods, troubleshooting, and repairs. For example when I was working on debugging and repair of my 1987A Plexi I found it handy that people had compiled test point voltages for the 1959SLP and appended those to the schematic. The two amps were similar enough that the information helped me check things quickly. The next time I'm inside my Mark V chassis I'll take some good photos, and if I have time I will make a spreadsheet of AC and DC voltages at test points with well defined control settings.