Mojotone JTM45 Schematic in Emailable Form?

[The New Steve H]

A guy from my church hooked me up with a disabled vet who is working on his first amp. It's a Mojotone JTM45 with EL34 tubes. He is a little nervous about building it, and I am trying to help. I strongly recommended Amp Garage, since everyone here is so brilliant and whatnot. I also said he really needed a current limiter.

Does anyone know if the schematic or layout is available somewhere in pdf or jpg format? He has giant paper versions, but he would have to get them scanned in order to send them to me. He's up the coast a ways. I hate to put him to the trouble, since it may not be easy for him to get around.

[Phil_S]

Not Mojo, but I think original attached. Maybe he can do the compare and tell you what's not the same.

A forum where this amp is of interest:
http://www.45watt.com/

[ToneMerc]

Actually, it's not a JTM45, it's a JTM50. On second thought, I don't know what's in that Mojo kit. It states a 1987 circuit, but it has a GZ34 rectifier and I think I see a .68 cap. Nevertheless, the JTM45 & 50 front ends are different as the 1987 has the split cathode arrangement on V1.

Before I get too committed in that build, I would verify exactly what it is. A JTM and a 1987 are different animals.

TM

[The New Steve H]

Thanks. I'll see if this is useful. If not, I can always drive up there.

[andyhardy]

Here is a web step by step instructions for the mojotone

http://acapella.harmony-central.com/sho ... structions

you can download metroamps jtm45 kit build guide from here

http://www.metroamp.com/downloads/JTM_45_KIT_V2.1.pdf

Cheers

[The New Steve H]

I have a feeling I'm in for a long drive this week! Thanks for the help, though.

[Structo]

Steve if you can just narrow down which amp he is building I'm sure you can find the right layout.
But if this guy doesn't know much about electronics, he probably needs hands on help.
That's great you are helping him out.

[The New Steve H]

I contacted Mojotone. They say they think they can email something. We'll see.

[The New Steve H]

It turns out one of the guys at Mojotone served in the Marine Corps, and he was glad to send the files. I just sent them to the guy with the kit, so he can compare them with what he has.

[andyhardy]

Here Are schematic and layout

[The New Steve H]

Here is what Jason at Mojotone sent me.

[The New Steve H]

This guy has a problem with some of the resistors in the Mojotone kit. He says the leads aren't long enough to cover the distance between the turrets. I suggested he tell me what values he needs, since I probably have them lying around. He is considering patching them with wire or something.

Have any of you dealt with kits that had this problem? Seems to me the best approach is to go with new resistors, since the odds that I have them here are about 75%.

[Zippy]

This guy has a problem with some of the resistors in the Mojotone kit. He says the leads aren't long enough to cover the distance between the turrets. I suggested he tell me what values he needs, since I probably have them lying around. He is considering patching them with wire or something.

Have any of you dealt with kits that had this problem? Seems to me the best approach is to go with new resistors, since the odds that I have them here are about 75%.

Hmmm, maybe he's trying to run the resistors to the wrong turrets?

[The New Steve H]

That's what I wondered, but he says he's sure they're the right ones. He doesn't want me to send him new ones. I think he is determined to try to fix them.

Now he wants to know if it's okay to make a break in a wire's insulation and solder the bare part to a pin, instead of cutting the wire. I know electricians do this on electric sockets, but it seems like it would be hard to make a good mechanical connection, and it would also be bulky.

[ToneMerc]

This guy has a problem with some of the resistors in the Mojotone kit. He says the leads aren't long enough to cover the distance between the turrets. I suggested he tell me what values he needs, since I probably have them lying around. He is considering patching them with wire or something.

Have any of you dealt with kits that had this problem? Seems to me the best approach is to go with new resistors, since the odds that I have them here are about 75%.

Actually, it's not that uncommon.

On a true orig/clone board the center-center turrent spacing is around 2.650", with about the same at V2's cathode. Well, in the age of pcb boards you are just not going to find many resistors with vintage era lead lengths. The original resistors such as Piher,Iskra, and Morganite/Allen Bradley all had lead lengths around 3.200".

If you look on a Ceriatone JTM layout you will see that the turrent spacing for V1 & V2 is shorter. I think it's obvious that he did this so that a cross section of modern resistors would fit in those turrent positions.

One way around this is to use A-B carbon comp resistors, the lead lengths are around 3.150".

TM