Vintage tape recorder repair/mod questions

[Om_Audio]

Hey guys,

I got this tape recorder and it is way cool but only records a faint sound and you have to be yelling into the mic to even get that. Tried diff mic too w same result. Everything works- just wondering if there are things to look at for starters to fix the recording issue. I am going to degauss the head and guides tomorrow but cannot imagine there is enough static to erase the tape that much. Caps? I know they can dry out. It does have 6 og Ge trannys in it, that's neat.

Also, I would like to see if I can increase the range of the speed adjust. It is controlled by an old style variable resistor- do those wear out? I think it is just a length of coiled wire so I doubt it- if it works it works.

Any help greatly appreciated!!

The item came with all the docs and orig box (cool!). Here is the schem- and a link to all the docs and preliminary gut shots at the very bottom of this post.


More pics:
https://plus.google.com/photos/105266388149148864163/albums/5914826430026866081

[Thomas_H]

I think its a good idea to degauss the head and clean it. If the heads are worn out you (tape took too much material off the head already) you need some luck to get a new one.

[Om_Audio]

Unit looks hardly used. Degaussed and cleaned head- no change.
Thx,
C

[Om_Audio]

Bump, I know there are some experts here...

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[oldhousescott]

Do you have a scope? You need to check that the bias oscillator is working and putting out the correct level.

[lincolnic]

Do you have a scope? You need to check that the bias oscillator is working and putting out the correct level.

This is true in general, but I don't think a mis-biased machine would be the cause of a super low level. It would give you more intermodulation distortion, but not a crazy low level.

Thought: how much alignment can you do on this machine? If you can align the record level, a previous owner might have cranked it way down.

[Om_Audio]

Thanks guys. (Wow, new forum platform!!)
I do not have a scope. I have a DMM and I flipped the board and there are no trimmers anywhere to be seen. No idea on how much alignment I can do because I have never done it. :/
I am a VERY quick study though if you have suggestions!
https://plus.google.com/photos/105266388149148864163/albums/5914826430026866081

C

[lincolnic]

I didn't realize it was a consumer model. I looked through the documents you posted and it doesn't look like you can do any alignment or biasing on your machine.

This might be obvious, but the manual says that you should change the 9v battery if the reproduced sound becomes faint. Maybe that's it? Or maybe something in the circuit around the record level control has gone bad? Just thinking out loud.

[Om_Audio]

Thanks man,  the batteries,  yes! I will try as soon as I get home. It has separate batteries for the motors and the rest. Will look closer at the schematic in more detail ASAP.
Thanks again,
C

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[Om_Audio]

Batteries are fine, so that rules that out.

Looks like there are a few things down the line from the mic input-

.005u cap
switch
.1u cap
Ge tranny
3k, 10k, 40k resistors
30u cap (pol)
3k, 5k, 3k,
etc.

It all flows together, and there actually is no REC level control- just speaker volume and a variable resistor for tape speed.



C

[lincolnic]

Huh, weird. Maybe it needs to be recapped, then? That's probably the last good idea I have...anything beyond that probably requires more knowledge than I've got!

[Om_Audio]

OK,  thank you very much. I was thinking same,  def place to start, will report back after I get parts and re-cap.
C

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