Lyrec AR4 (from a TR-16) schematic needed

[Conviction]

Hi all,

As the topic says, I'm looking for a Lyrec A4 schematic (the record/playback amp). I think the AR4 was originally mounted into a TR16 recorder. The rest of the machine is - sadly - long gone, but with a little luck the AR4 will do as a two channel microphone preamp.

So far, I've replaced the head input (20K line transformer) with a 200R/60K transformer. This means I suddenly got two individual preamps, each with a JS output transformer.
Curious about the circuit as a whole, though.

Perhaps Lyrec still supplies schematics? Any tips appreciated.

 

[Conviction]

No schematic yet, but I've started to fiddle around with the preamp a little. It seems, though, that both inputs choke when the input level gets to high. The signal just cuts.
With a low pad (tried my CV-12 microphone), the problem's gone.

The "level" controls are two 50k wire-wound pots. They were, of course, originally fixed. You might notice them in the pictures.

Here goes:

There's trim capacitors for each channel, but I'm rather clueless here without a schematic. Perhaps any of you got ideas where to start?
Is this due to too high level input?

* Please ignore the the input transformer quick fix installation (top left).

 

[Bo Hansen]

Conviction,

Here is the Lyrec TR-16 schematics you talk about.
The AR4 record/playback amp and also the rest of tape transport electronics.


--Bo

 

[Bo Hansen]

And one more schematic.

 

[gyraf]

Interesting - I haven't seen that type of choke-in-cathode-circuit before.

Can anyone explain?

Jakob E.

 

[Conviction]

Thanks to Bosse for the schematic!