Mojotone Amp Kits Leave A Lot To Be Desired........................

[Jeffblue]

I am nearly finished with my Mojotone Studio One build, but..........the power transformer is defective. I have over 300 volts DC at the diode rectifier and no power at the pilot lamp and filaments. No filaments, no electron flow. I keep trying to call and there is no answer.

The Studio One kit arrived with the front and rear face plates on back order with the wrong tag board, missing two chickenhead knobs, missing a 220k ohm 1/2 watt resistor, missing one 4-40 machine screw for mounting the tag board. Two of the holes in the chassis for mounting the tag board are misaligned so the tag board is only anchored by two screws (with all four stand-offs installed)

This is my first amp build and it has been made more difficult with having to improvise. Mojotone didn't provide enough color coded wire to match the diagram so I used another color wire. I provided my own MIL spec teflon coated wire for all the grounds to chassis in a dual star ground. I am very disappointed because the hold up is strictly Mojotone. I am still waiting for my face plates. THis amp is totally useless without a functioning power transformer.

 

[GoldenVulture]

Re: Mojotone Amp Kits Leave A Lot To Be Desired........................

That all sounds like a very big letdown. Are you going to get them to replace the transformer ? It seems like it was defective from the beginning.

 

[Artie]

Re: Mojotone Amp Kits Leave A Lot To Be Desired........................

Man, that sucks. And if I recall, those things aren't cheap.

 

[leevc5]

Re: Mojotone Amp Kits Leave A Lot To Be Desired........................

I am nearly finished with my Mojotone Studio One build, but..........the power transformer is defective. I have over 300 volts DC at the diode rectifier and no power at the pilot lamp and filaments. No filaments, no electron flow. I keep trying to call and there is no answer.

The Studio One kit arrived with the front and rear face plates on back order with the wrong tag board, missing two chickenhead knobs, missing a 220k ohm 1/2 watt resistor, missing one 4-40 machine screw for mounting the tag board. Two of the holes in the chassis for mounting the tag board are misaligned so the tag board is only anchored by two screws (with all four stand-offs installed)

This is my first amp build and it has been made more difficult with having to improvise. Mojotone didn't provide enough color coded wire to match the diagram so I used another color wire. I provided my own MIL spec teflon coated wire for all the grounds to chassis in a dual star ground. I am very disappointed because the hold up is strictly Mojotone. I am still waiting for my face plates. THis amp is totally useless without a functioning power transformer.

Not unusual, I had the same problem with a kit Co., won't mention the name because they overnighted the replacement xfmr and missing parts. Nonetheless, now I order the parts I need for a build myself from a few different suppliers. I get what I need and save about 25%.

 

[Jeffblue]

Re: Mojotone Amp Kits Leave A Lot To Be Desired........................

Mojotone emailed me after I emailed them. After taking some detailed photos and review by their engineer, I, hopefully, will be receiving a new power transformer. Either the filament windings work or they don't. The PT runs dangerously hot. This build is taking too long. I should already be playing through this amp. This back and forth is making me tired.

 

[leevc5]

Re: Mojotone Amp Kits Leave A Lot To Be Desired........................

Builds are fun, rewarding and educational, I have been doing them for years. But, the Chinese are coming and building an amp now has become a zero sum game:
http://www.mcmelectronics.com/product/555-28015
My current build is a hybrid using tube preamp going into the power amp stage of a Fender Bronco solid state amp I had lying around.

 

[LLL]

Re: Mojotone Amp Kits Leave A Lot To Be Desired........................

Sucks. Seems like no one gives a **** about taking pride in their job (esp. the little details) anymore.

Reminds me of the time when I ordered a PTP kit from Metroamp - the dumb**** sent me the wrong phenolic board twice...
third time he got it right.

 

[Jeffblue]

Re: Mojotone Amp Kits Leave A Lot To Be Desired........................

The PT is fine. Steve Snyder from Mojotone sent me back a photo that I sent him and circled where a wire didn't belong on the switch relay board. I made the appropriate adjustments. He also sent me an instruction manual with actual photos and details that wasn't included with my amp kit. I would have wired the switch relay board correctly if this information were included with the kit. The pilot light and the wiring for the filaments and the plates are all energized. Problem, the filaments still wont light. How can this be? I am hoping Steve will get back to me about this issue. (Steve is the designer/creator of the Studio One amp)

 

[NjuiMusic]

Re: Mojotone Amp Kits Leave A Lot To Be Desired........................

I got my kit from Triode electronics, had no issues with them!

 

[leevc5]

Re: Mojotone Amp Kits Leave A Lot To Be Desired........................

The PT is fine. Steve Snyder from Mojotone sent me back a photo that I sent him and circled where a wire didn't belong on the switch relay board. I made the appropriate adjustments. He also sent me an instruction manual with actual photos and details that wasn't included with my amp kit. I would have wired the switch relay board correctly if this information were included with the kit. The pilot light and the wiring for the filaments and the plates are all energized. Problem, the filaments still wont light. How can this be? I am hoping Steve will get back to me about this issue. (Steve is the designer/creator of the Studio One amp)

Perhaps the tubes were damaged as a result of the miswire. Try changing out one of the tubes and see if it lights up.

 

[Darg1911]

Re: Mojotone Amp Kits Leave A Lot To Be Desired........................

Dumb question maybe but have you checked voltages with a meter? Filaments would probably be close to 7 volts (ac) with no tubes in the sockets.

 

[Jeffblue]

Re: Mojotone Amp Kits Leave A Lot To Be Desired........................

Steve from Mojotone emailed me after I emailed him and asked me to send photos of the build progress. He sent a photo back of the foot switch relay board and circled around where I had wired the board incorrectly causing a direct short. He also sent a detailed PDF instruction manual (that wasn't included with the kit) that has excellent photos of how to wire the board. The diagram that came with the amp kit was very vague and no real details of the foot switch relay board. I did rewire the board and rewired the filament wires (because I had wired those incorrectly also) Well, after all that the amp still wasn't working so I started checking voltages. I was reading 344 volts DC on pins 1 and 6 on the output tube. I then checked pins 1 and 6 of both preamp sockets and the driver socket and I was reading approximately 0.619 volts DC. WHAT? Then I checked the output socket again then suddenly I had arcing and plasma between pins 5 and 6. I quickly pulled the power cord and blew out the flame. Steve from Mojotone emailed me and let me know that I will need to replace the output tube socket. This is becoming a comedy of errors. I ordered a new tube socket and some new teflon coated wire to replace the filament wiring. I will keep you apprised as I go along. I will not give up.

 

[TwilightOdyssey]

Re: Mojotone Amp Kits Leave A Lot To Be Desired........................

Sounds frustrating.
You have a much longer fuse than I do!

 

[YeRedHouseOverYonder]

Re: Mojotone Amp Kits Leave A Lot To Be Desired........................

Yikes. Hope you get it sorted out soon. I've seen a couple of kits (JTM 45/DC30) that I'd be interested in, but with my luck, I'd have issues beyond belief. Good luck man.


Sent from my iPhone using Tapatalk

 

[Lampy H]

Re: Mojotone Amp Kits Leave A Lot To Be Desired........................

That all sounds agonizing. I hope you at least like the tone when the amp is finished.

I did buy a 112 from them, and I'm very happy with it.

 

[Scott_F]

Re: Mojotone Amp Kits Leave A Lot To Be Desired........................

Building amps is fun. Supporting amp kits must be a nightmare. Hang in there.

 

[Jeffblue]

Re: Mojotone Amp Kits Leave A Lot To Be Desired........................

Hey all,

I finally got the Studio One amp working. The number 1 preamp tube isn't as bright as the other tubes. The volume is way too low with an intermittent proper loudness in volume. Cold solder joint? I can tell that this amp is going to sound excellent when I'm finished. I want to thank you all for your input and help.

 

[Demanic]

Re: Mojotone Amp Kits Leave A Lot To Be Desired........................

Maybe, or bad tube. Keep at it though, you're almost there!

Sent from my MotoE2(4G-LTE) using Tapatalk

 

[Scott_F]

Re: Mojotone Amp Kits Leave A Lot To Be Desired........................

Swap tubes.

 

[Scott_F]

Re: Mojotone Amp Kits Leave A Lot To Be Desired........................

Check the resistor coming off pin 3 and 8. Make sure right value.