[Premium-Rx] wj 205 / RS-160 receiver disaster - ps cabling information needed

[Peter Ratuschni]

It looks like the wj 205 and its documentation is far too scarce.

Finally I concluded that transistor Q2 was installed wrong; first I guess that it must be mounted isolated from the chassis. Next, the wires connecting collector and emitter were interchanged. The collector has to be the regulated negative output and the emitter the negative input which is connected to the rectifier diodes on A12 and to C2-.

Together with the wrong wired mains transformer someone did a very effective repair to death.

Maybe the 205 from 1970 was one of the very first receivers with the automatic pan feature using only semiconductors - the heavy motor-units for tuning conventional tuners were still sold in the seventies. I do have one such wj MD unit, and that makes me recognize how smart the varactor based units are. (Though, I still love the inductotuners).

I hope I can revive the unit. Some of the transistors are hard to find and so it will probably take longer.

b.r.
Peter


> Gesendet: Montag, 16. Juni 2014 um 14:51 Uhr
> Von: "Peter Ratuschni" <zpz at gmx.de>
> An: premium-rx <premium-rx at mailman.qth.net>
> Betreff: [Premium-Rx] wj 205 / RS-160 receiver disaster - ps cabling information needed
>
> Hello all,
> 
> I was given a wj 205-3 receiver with a CSU-160 tuner rack. Unfortunately the 205 has a lot of components which failed shorted. The reason was a wrong mounted mains transformer - the mains voltage was connected to the secondary windings.
> The transformer still seems to be ok and now the connections are right - but it is likely that there are even more cabling faults in the power supply.
> 
> From the both regulation transistors Q1,Q2 (both 2N3055) only Q1 was mounted isolated from the chassis. Q2 has a connection from the collector to ground. This shorts filter cap C2, which is connected with it`s negative terminal to Q2-C and to ground with it`s positive terminal.
> I guess the mounting of Q2 is ok, as the socket of Q2 is smaller than of the isolated mounted Q1. 
> So one could guess, that C2 has interchanged connections, but I am not shure. 
> 
> The 205 does not use the typical wj dual voltage supply design of the seventies with two 723 regulators. So any help is welcome. The best would be to obtain the schematics, as at least one resistor is burned and the value can not be identified anymore.
> 
> best regards,
> Peter
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