Trying to get a Stellavox SM8 working

[dlozanothornton]

So,  I'm located in the UK and I've got my stellavox sm8 tape recorder back from being fixed up and upgraded.
Unfortunately, there are issues, one channel is about 4db louder than the other and the entire thing jumps about 10db in level when in record compared to test mode. I've tried replacing all the playback amplifiers and it hasn't fixed anything. The fixer man hasn't replied so he might be away or something.
The heads are clean and looking inside it all LOOKs okay.. The mechanics and functions are all operating.
I'll upload all the schematics to see if anyone can help me think of solutions, and to understand the level difference between channels.
Failing that, does anyone know anyone in the U.K skilled enough to fix it?

 

[dlozanothornton]

playback circuit

 

[dlozanothornton]

stereo head assembly

 

[dlozanothornton]

Stereo head further...

 

[dlozanothornton]

full schematic.

 

[abbey road d enfer]

These are not schematics, they are block diagrams; in fact, they're exactly what you want for troubleshooting 101. Just check and compare both cahnnels at each input and output of the various blocks.
Your description of the fault is too vague, when you say one channel is louder than the other, is it in playback or input mode, do you see that on the meters as well as hear it? It could be so many things, but I suspect the alignment is wrong; the fact that it comes from a complete overhaul and shows so much problems does not inspire confidence in the person who did it...

 

[dlozanothornton]

you are correct, these are just block diagrams, the actual modules are pulled out and replaced if faulty, generally,
The left channel is louder on the meter, audibly, recorded into digital and everything and I just realized, after changing the playback amplifiers it is happening in the input somewhere. I have swapped out the input amplifers for new ones already and that fixed a prior issue (strange high frequency distortion on the right channel) but did not alter the level difference...
it doesn't matter if it is line, microphone or mixer input, no difference, it seems.
The alignment is tricky as it is resistor based.
I agree very much on the final point.

 

[sorscha]

Hello, Probably the recorder is not aligned to a tape. (hence the big difference in direct/tape). The question is who 'fixed it' and why hasn't the machine set to a tape. The tape head goes to the repro-amps, and a line is fed back into the heads block for equalisation. Having said that: The reproduce level is set by a capacitor, 10kHz by the variable resistor, and at 60Hz with the resistor. This is only repro. Aligning record is a whole different cookie. Either send it to Jean-Michel in Switzerland (Stellavox), or to me (Holland). Setting a heads block to a tape is not fun if you have never done it before. There are quite some things to keep in mind.

 

[gyraf]

(question was 5 years old..)

 

[abbey road d enfer]

(question was 5 years old..)

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