Author Topic: TOELLNET TOE7401 function generator repair. Need schematics / service manual ?  (Read 792 times)

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Offline Noy

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Hi guys,
i have shot a TOE7401 on ebay.
It looks like its partly working. The output works with a high impedance probe / 50 Ohm BNC cable to my DS1054z without a 50 Ohm throughput termination and it seems fine. But as soon as i connect it with a 50 Ohm throughput terminator the signal is "dead". I think the output amplifier is broken.
Does somebody have a service manual or a schematic from the function generator?
 

Offline coromonadalix

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Well if you ask them directly ?   or maybe tell them under an non diclosure agreement, maybe they could send you an service manual ???  you never know

the only service manual ive found is this : https://elektrotanya.com/toellner_7740,7750_function_generator.pdf/download.html     

It may help you in some way ?  maybe some ressemblance in the output power stage,    you should have an 20 volts output  with an +/- 10 volts offset on a 50 ohms load ??
« Last Edit: December 13, 2018, 02:44:51 am by coromonadalix »
 

Offline babysitter

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Toellner is nice, they give you the manuals, I got it in hours after my request(but was asked to keep it.)
I'm not a feature, I'm a bug! ARC DG3HDA
 

Offline ktulu

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Just a few days ago I was also searching for TOE 7404 schematic, service manual.
I sent 2 mails to Toellner, but received no reply.
(the manual on that link posted by coromonadalix was uploaded after that)
I have the newer model with frequency counter, and a completely different all smd PCB.
There is a 6 page long pdf that I've found with a quick search, that should have 16 pages with schematic and calibration instructions, but unfortunately it is cropped.
 

Offline Noy

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I asked Toellner already a few weeks ago.
Got some manuals with everything in it but it was for the old fully THT variant. I have a newer full SMD one completly different mounting references. So it is not useable for me.
But i found the issue, Oxidation at the output fuse. Cleaned it with a glass pencil.
But i think i need to adjust it new.
And for this i need a manual which is for my version to find the correct potentiometer in the pcb.

 

Offline mldevw

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Hi,

I was in the same situation as you a few days ago, but then I found
http://www.ko4bb.com/getsimple/index.php?id=download&file=06_Misc_Test_Equipment/Toellner_TOE_7402_7404_7702_7_LF_signal_generator_operating_and_Service_Manual.pdf

It's a great manual with detailed schematics.

Good luck fixing your device!
Cheers,

mldevw
 

Offline Noy

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I have this manual already. But it is for THT variant.
Please see my pictures. On the small Board we're 2 thyristors mounted. For example the potentiometer in this Board is completly missing in the old manual.
Maybe i can find out which potentiometer is which with the old schematic with some deeper searching.
 

Offline Noy

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Now with Pictures...
 

Offline Noy

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Back working....

Dirt / Oxid on the contacts from the fuse caused the problem...
Cleaned it with a glaspencil and now everything is fine.
 


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