Jen - Motorphaser

Discussion regarding early stompbox technology: 1960-1975 Please keep discussion focused and contribute what info you have...
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777seven777
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Post by 777seven777 »

Hi
I'm trying to fix a JEN Motorphaser, but I don't have a schedule, does anyone here in the forum have something they could share.

//sven

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karul
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Post by karul »

Can you post some pictures of it, both sides ?

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777seven777
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Post by 777seven777 »

I have attached the photos, I hope you can see them, I get sound through the pedal but I cannot get the modulation to work.
//sven
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Topp side
Topp side
IMG_0689.JPG (76.42 KiB) Viewed 4765 times
copper side
copper side
IMG_0688.JPG (73.14 KiB) Viewed 4765 times

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tube-exorcist
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Post by tube-exorcist »

777seven777 wrote:I have attached the photos, I hope you can see them, I get sound through the pedal but I cannot get the modulation to work.
//sven
Nice that you have an iPhone 5. Now you only need a better light, a stable hand and you have to find the macro setting (most of the time a flower symbol) to make sharp and usable pictures.
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Post by 777seven777 »

I will bring out my real camera..

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Post by 777seven777 »

These are a lot better
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Topside
Topside
Copperside
Copperside

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rocklander
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Post by rocklander »

thanks!.
now can you please identify the following 25 components for us? (values/part numbers).
Jen Motorphase.jpg
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Post by tube-exorcist »

rocklander wrote:thanks!.
now can you please identify the following 25 components for us? (values/part numbers).
Jen Motorphase.jpg
25.....

now the big silver cans are 741,...

- 7 makes 18...

the round transistors are 2N5163 FET´s, .....

- 5 makes 13....

the light blue electrolytic is 100µ/25V,...

- 1 makes 12....

the trimmer beside this electrolytic is 22k....

- 1 makes 11...

the trimmer beside the 1M resistor on the left side is 220k...

- 1 makes 10....

yes and if you take a Mxr Phase 90 schematic on your desk while tracing it can be helpful....
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Post by tube-exorcist »

...and for the LFO section have a look at the Maestro PS-1A/PS1B (v2 + v3) schematic.
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Post by sinner »

Can I have the pots values?

I will rework the pcb and get the schematic done by the middle of the week

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Post by 777seven777 »

I have checked all pot values, there is also a bipolar capacitor. And I have added data for the Three transistors, hopefully you can read the text..
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Motorphase_pic.jpg

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Post by sinner »

Cool. I will start to roll it tonite

What's the board dimensions in inches?

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Post by 777seven777 »

It is 110x88 (in millimeters)

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Post by smilan »

Hi,
I know this post is quite old but I need some help with fixing my motorphase.
A friend of mine wave me this Jen Motorphaser pedal in un-working condition.
Since I can not find the schematics for it I need some help with rewiring this pedal.
The two wires coming from the output jack are cut and I don't know where to connect them?
I made this sketch that shows the connections between the PCB board to the input / output jacks and to the switches.

Image
Besides the cuted wires I've noticed that the former owner replaced many components on the board.
I would like to recap all the film caps with new wima caps.
The opamps on the board are ca741ce, those are the original opamps for this pedal?
What about the transistors?
there are five u1899e (round ones) and two bc238b, those are the right ones?

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Post by smilan »

So I've wired the output jack and the effect working now, but my problem is that when I'm setting the trimmers I'm getting good sound but after few seconds the phaser effect fades and I need to play with the trimmer to get the phaser back, but after few seconds it's gone again. See this video and see this problem:

What components on the PCD can causing this kind of problem?

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Post by fuzzbunny »

Maybe the trimmers are the problem?
Try hitting them with Deoxit.

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Post by smilan »

So I think I've managed to repair my pedal!
I replaced all the 741 op amps with new ones, I've also I replaced few trimmers and one bad resistor and now it's rocking again!
There's still some notable noise coming out from this pedal, but I don't know if this is how it works or there's something else to check?
This is how it sounds:

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Post by BMS1971 »

I know this post is old but anyone did the schematic ?
Cheers
Benoit

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