Texar Audio Prism> schematic MB-1 wanted

[Parasound]

Hello

I'm looking for a schematic of the MB -1 Motherboard of the Texar Audio Prism.

I hope their is someone willing to help me out.

thanks

 

[HOMEYD]

The manual is at the link below:


www.clearone.com/docs/manuals/LG-000-00009-Rev1.0_PrismII-FM-Man.pdf

 

[Parasound]

Thanks HOMEYD.

But I have this manual allready.

The MB1 was in the first Texar's till serialnumber 500

thnx

 

[BROADCAST]

I had a pair of pre 500 serial prisms,i had to draw out my own schematics on these.
What part of the circuitry are you looking for?

Paul.

 

[Parasound]

Hello Paul..

Thanx for your reply. You seem to be very busy on audio processing!

I just want to complete my documentation of the Audio Prism.

When you callibrate a prisms buffer circuit on the motherboard, there is a feedpoint on the MB2 motherboard, at the jumper of the Phase rotator. There you can feed an audio signal without disturbing any OpAmps
I want to know, where i can feed a signal to the buffer circuit on the MB-1, without disturbing any OpAmp in the circuit.

Maybe you can help me. If I have both schematics, I can find it myslef, but I can't compare now..

Regards Dennis

 

[BROADCAST]

If i remember right,i fed the audio oscillator in and probed u301b's o/p for the desired level,then worked from there.
Or you would have to lift r334 to inject the osc,as their is no jumpers you have no choice.

When i worked on mine years ago i ended up doing various mods,i had to change the mains transformer,the pre 500 serial ones dropped out of regulation(15v)due to low ac secondary voltages,every reg board has the pcb burned under the regs that i have seen!
I contacted Glen Clark and he said to replace the LP-30 transformers to LP-34's.
I still have his emails regarding the old prisms.

I have always heatsunk the regs to the case to reduce heat,the regs run far too hot.

Also Glen says the led displays cause hash on the rails due to how the supply is routed through the main board,this was improved on the later models.

Also the m100 boards are different than the later m101 boards,this is what i can find of my schetches,the gain set and bias set cicuitry is far coarser on the old units.

 

[BROADCAST]

Regarding some of the differences between the pre 500 models and later Glen says(cut and pasting an email from him),

Those were very early prisms. 326 and 327 are Scott asset tag
numbers. 296 and 297 are the TEXAR numbers. We didn't start
putting serial numbers on the outside until about serial 500.

Those versions have the MB-1 instead of the MB-2 motherboards
and the CX-1 instead of the CX-2 motherboards. That means you
get bar graphs instead of dot graphs. Also, the MB-2 has more filtering
to and separate power busses for the lights and the audio. On the MB-1,
hash from the displays would backfeed the op-amp power connections.

 

[Parasound]

Hello Paul

Thanks for your reply and your help.
I'll give it a try.

For your knowledge ( and others)
Hammond Electronics has replacement Transformers for Signal

The Signal LP34-340 is available as a Hammond 229-b34

After serial number 1300, Texar has used Custom made transformers. Because the old power supply couldn't drive a prism with the Eagle ( AMC-2) board installed.