Vox V1143 Super Beatle schemo

[Mars Amp Repair]

Hello folks,
I have a vox Super Beatle mod V1143. It has a bunch of what I think are FET's in the input stages & wonder if anyone has the schemo for this version. I have a schemo of the Viscount mod V1154 which may be very similar & uses the FET's, but they have no part number on the schemo. Does anyone have experience replacing these FETS & what worked successfully.

I found the Super Beatle mod# V1141 version which uses bipolar's in the inputs.

These are probably just your run of the mill N-channel fets. they are marked '5095' but don't match the datasheet for the 2N5095's.

I'll have to replace all the electrolytics in this amp I know, but I'd like to first see if I can get the bass channel working. the caps around it see ok.

thanx, glen

[olddawg]

Hello folks,
I have a vox Super Beatle mod V1143. It has a bunch of what I think are FET's in the input stages & wonder if anyone has the schemo for this version. I have a schemo of the Viscount mod V1154 which may be very similar & uses the FET's, but they have no part number on the schemo. Does anyone have experience replacing these FETS & what worked successfully.

I found the Super Beatle mod# V1141 version which uses bipolar's in the inputs.

These are probably just your run of the mill N-channel fets. they are marked '5095' but don't match the datasheet for the 2N5095's.

I'll have to replace all the electrolytics in this amp I know, but I'd like to first see if I can get the bass channel working. the caps around it see ok.

thanx, glen

I can't help you with a schematic but I am pretty sure that there are no FETs in a Super Beetle. I don't think that FETs were even available at the time the amp was made. As far as I know that amp is all discrete bipolar technology and a famous headache at that.

[imbuedblue]

5095 is part of Thomas Organ's internal part numbering system. They are just relabelled 2N4303. There should also be some P-channel FETs marked 5098 which are relabelled 2N4343.

[Bruce / Mission Amps]

I can't help you with a schematic but I am pretty sure that there are no FETs in a Super Beetle. I don't think that FETs were even available at the time the amp was made. As far as I know that amp is all discrete bipolar technology and a famous headache at that.

Not sure myself but I think FETs (unipolar transistors) were "invented" before bipolar transistors.
Glen, I really don't think I've noticed FETs in any of those old VOX amps.
I remember going over to Gateway when they first moved over on Federal and buying Motorola police siren, transistor amp finals for the VOX PA section and they worked perfectly!
RG Keen might now about the preamp transistors though...

[olddawg]

Not sure myself but I think FETs (unipolar transistors) were "invented" before bipolar transistors.
Glen, I really don't think I've noticed FETs in any of those old VOX amps.
I remember going over to Gateway when they first moved over on Federal and buying Motorola police siren, transistor amp finals for the VOX PA section and they worked perfectly!
RG Keen might now about the preamp transistors though...

That's possible I guess. If they were invented before bipolar transistors would they be germanium FETs? I don't remember seeing any FETs in any 60s solid state equipment. I know that we studied them when I got my AS Electronic degree in the late 70s so they had to be around. So I could be wrong.

[imbuedblue]

I can't help you with a schematic but I am pretty sure that there are no FETs in a Super Beetle. I don't think that FETs were even available at the time the amp was made. As far as I know that amp is all discrete bipolar technology and a famous headache at that.

Thomas/Vox started using FETs near the end. The V1143 was the only Super Beatle to use FETs. FETs are also in the Buckingham V1123, Guardsman V1133, Viscount V1153, and Viscount V1154.

[olddawg]

Thomas/Vox started using FETs near the end. The V1143 was the only Super Beatle to use FETs. FETs are also in the Buckingham V1123, Guardsman V1133, Viscount V1153, and Viscount V1154.

Well shut my mouth. I always hated those amps anyway.

[Mars Amp Repair]

thanx guys,
I forgot that you need that silly tuner ckt in the cab needs to be connected to provide a ground for the FETin the bass channel...BTW, it is a FET & thanx for the cross-reference for future needs.

It appears at least the preamp section of the VISCOUNT MOD#V1154 is pretty close to the Super Beatle V1143 w/FET input xistors.

Thanx,glen

[Mars Amp Repair]

OOPS
I missed the comments below my reply thread. thanx all for the good info...glen

[Mars Amp Repair]

interesting!
So, did the police siren finals just fit right in there with some wiring mods?...Interesting what we techs figure to do when the need arises...glen

[R.G.]

Here I am late again.

Yes, the 1??3*6 versions of all the "big head" Thomas Vox amps used JFETs as input devices, and I believe also as signal switches for the distortion. I know the 1143*6 Beatle used them as both inputs and signal path switches.

All the TO-92 small signal NPNs can be replaced with 2N5088. I'll have to look up the JFETs, but probably 2N5485 would work for the N-channels. Practically any p-channel switch JFET will work for the P-channel one in the signal routing.

The "finals" are house numbered 2N3055's, which back in the day was used for almost every NPN power output job it could be conceivably used in; it does not surprise me at all that it got into sirens, as it was the cheapest, most easily available good NPN that could be had. They were made by the zillions and used in everything that would not simply fry them immediately.

They are ... barely... adequate in the Beatle, largely because they have only a 60V BVceo, and the power supply's 62-64V. Probably what saves them is that the supply sags under load.

You remember that funny-looking girl you all made fun of and everyone refused to ask out in high school? It's pretty certain that someone thought she was lovely and talented, and married her. 8-)

I mention that because there is a cadre of us that think the Thomas Vox amps do sound good - certainly acceptable even if not the very best amps in the cork-sniffing sense. I've heard a lot worse. But they are dreadful to work on because of the mechanical setup; hard to get into, oddly wired, and difficult not to break wires on as you fix whatever else was wrong. Every tech I've ever talked to that didn't already love them before digging in hated them after working on one for a while. Techs' opinions of how amps sound are colored by how hard they are to work on...

[R.G.]

Almost forgot - if you ever have a customer who refuses to pay for fixing one, tell them you know a chump who likes to buy them, and will take it off their hands. Then contact me.

8-)

Now, can you guess what kind of amp *I* wanted in high school and could never afford?

LOL.

[olddawg]

. You remember that funny-looking girl you all made fun of and everyone refused to ask out in high school? It's pretty certain that someone thought she was lovely and talented, and married her. 8-)

I mention that because there is a cadre of us that think the Thomas Vox amps do sound good - certainly acceptable even if not the very best amps in the cork-sniffing sense. I've heard a lot worse. But they are dreadful to work on because of the mechanical setup; hard to get into, oddly wired, and difficult not to break wires on as you fix whatever else was wrong. Every tech I've ever talked to that didn't already love them before digging in hated them after working on one for a while. Techs' opinions of how amps sound are colored by how hard they are to work on...

Naaa...That girl is now an angry hairy lesbian that hates your guts and the amp still sucks. I remember buying them working for $100 just to pull the speakers out and then throwing the metal frame, head and cab in the dumpster in the 70s.

[Bruce / Mission Amps]

Well shut my mouth. I always hated those amps anyway.

Ha ha... me too. But I've always loved the vacuum tube ones, especially the AC50s and AC100s, not so much the AC30.

[Mars Amp Repair]

HAH!
Of course this is a bass amp, but the only Vox I ever owned was the Essex on the metal wheely stand. 2X12 with (as I recall) only 2 controls...volume & tone. Man did it suck. Of course back then we were shooting for as much VOLUME as we could get & that amp failed miserably in that department...also sucked for tone, too, but I was only like 15yrs old & it was all I could afford (used of course).

The only other Vox amp anyone had was this Berkeley head that we kept hooked up & just used to kick to get that banging reverb noise...don't ask ;-[

Needless to say, we didnt' think much of the Vox products...g