Mojotone kits ?

[hebaton]

Just got a JTM45 clone assembled from a Mojotone kit. Wondering about parts quality. What is the general view on their signal caps ?
I have some old mustard .1 and .02 caps here. Should I replace the mojotone caps with those ?

Also, If anyone is familiar with the "one Wrie mod" how does this impact the amp when defeated ?

Thank you for any input provided

[Stevem]

Get yourself one of these.

I will be the best investment you ever make!

With this you will be able to see in numbers the difference between caps and then you now have a basis to better judge how they sound when you do audition them.

This also makes extremely precise resistance measurements if your into that.

Many times for me this in 3 seconds has found new resistors that where mismarked before I put them into an amp or into my stock, and the same with coupling caps.


NOTE that when you test electrolytic type caps with this tester you MUST discharge them first unless they are new, and even then it does not hurt to discharge them .

Also note that with this tester since it runs on a 9 volt battery the larger in Uf value a cap is the longer it will take for this unit to display a reading .

A 2000 uf cap might take 8 seconds to charge up .

[martin manning]

Just got a JTM45 clone assembled from a Mojotone kit. Wondering about parts quality. What is the general view on their signal caps ?
I have some old mustard .1 and .02 caps here. Should I replace the mojotone caps with those ?

Also, If anyone is familiar with the "one Wrie mod" how does this impact the amp when defeated ?

Thank you for any input provided

Parts quality is generally good, including the "Dijon" signal caps. I'm not sure if they are using name brand jacks and switches. Their own-branded pots are good, I believe they are sourcing them from CTS. In the parts kit photo's the pots look like Alpha's.

Here's a JTM45 with one wire mod in/out: https://www.youtube.com/watch?v=Pl5qXjIV8Xc

[hebaton]

Get yourself one of these.

I will be the best investment you ever make!

With this you will be able to see in numbers the difference between caps and then you now have a basis to better judge how they sound when you do audition them.

This also makes extremely precise resistance measurements if your into that.

Many times for me this in 3 seconds has found new resistors that where mismarked before I put them into an amp or into my stock, and the same with coupling caps.


NOTE that when you test electrolytic type caps with this tester you MUST discharge them first unless they are new, and even then it does not hurt to discharge them .

Also note that with this tester since it runs on a 9 volt battery the larger in Uf value a cap is the longer it will take for this unit to display a reading .

A 2000 uf cap might take 8 seconds to charge up .

Thank you, I have a Fluke 117 I think does a good job...

[lonote]

Get yourself one of these.

Thank you, I have a Fluke 117 I think does a good job...

In spite of having a really nice DMM, I would agree that those little testers are great. There is no range or type of measurement to set (cap, res, diode, etc).

You just hook up the leads, hit the button and it figures out what you are measuring and it's value.

I use one as I am populating boards & quickly measure every component as it goes on. Only a few seconds each & it eliminates that many more potential issues.

There are cheaper ones out there as well, thinking I paid well under $20 for mine.

[Stevem]

You our 117 while it’s a great meter does not do what this item does!

[johnnyreece]

Just wanna chime in and agree about that little meter. My old meter didn't test caps, so I snagged one of these for less than $20. It's just too easy to use, and if I accidentally cook it, I'm definitely getting another. Nice to have ESR and leakage measurements for caps.

[maxkracht]

Mojo kits are generally high quality. I think the bigger problem with buying an assembled mojo kit is who built it and how well. I've repaired some pretty horrible/dangerous kit builds purchased from ebay or reverb... There are also sometimes problems with the build documents like fusing the neutral wire.

[cdemike]

I had a good experience with the parts in the Hiwatt kit I bought from them about 2 years ago. All the pots in mine were 24mm Alphas, all the signal resistors were 1W Vishays, and Xicon branded ceramic sugar cube resistors for the B+ rail. Haven’t had any issues with their electrolytics. This is a nit-picky gripe, and one that’s avoidable if you’re careful about bending leads, but I’ve found that their Dijon caps’ housings can crack if you’re not careful about minimizing stress on the joint between the leads and the housing. That’s true for all caps, though, and it’s something I’ve only encountered with Mojo Dijons specifically after they have been used, removed, and entered service as spares where they’re soldered in and out of projects repeatedly — admittedly a pretty tough set of conditions for any capacitor.

Agree with Max about the other issues more broadly with the Mojo kit. IIRC, the colors of my OT secondary leads didn’t match what was on the layout they sent with the kit. Also, their 100w Marshall schematic doesn’t correspond with 4-hole Marshall that I’m aware of with both lead and bass spec sharing a 56k/500pf tone stack — should be either 33k/500pf or 56k/250pf, respectively, and makes a pretty significant difference in how the amp sounds.

[hebaton]

You our 117 while it’s a great meter does not do what this item does!

I am curious, What this meter does the 117 doesn't ?
I can certainly measure caps and resistors with it.

[hebaton]

About the quality of the work, here are a couple pics. I think it looks good, but I am not very knowlageble on this.
One thing I am debating is replacing the OT. This one has a 3.4K primary so it uses EL34S but I would like to use KT66 or 6550...
I am wondering about that One Wire mod. When I engage it, the "normal" volume seems to not do anything, I would expect both volume pots would be interacting no ?

[martin manning]

I am curious, What this meter does the 117 doesn't ?
I can certainly measure caps and resistors with it.

I don't think your Fluke 117 can measure small capacitances (<1nF), and it does not measure capacitor ESR. These little component testers function like an LCR meter, plus they can identify and test transistors for hfe and Ic0, and diodes for capacitance and leakage. https://www.amazon.com/FNIRSI-LCR-P1-Tr ... 8778&psc=1

[hebaton]

O.K. I get it. Thank you !
and this relatively cheap unit gives reasonnably accurate results ?

[xtian]

About the quality of the work, here are a couple pics.

Some solder points look OK, but many are ugly, and might be poor electrical connections. I'd go through and retouch.

[martin manning]

Yes, definitely not a "lab quality" device, but not bad at all, really. It was originally an open source project on a German microcontroller forum, but there are now many Asian products based on the design for sale. Scroll down in the Amazon listing to see the measurement functions.