Magnecord 1024 Modification Advice Needed

[Richard P]

I picked up a nice Magnecord 1024 recently and have the mechanical/electromechanical parts working properly. It plays well at both speeds but the output is very low. Looking at the electronics, the amp power supply voltages are a bit high @ 7.4 VAC (spec 6.3 VAC), -18.3 VDC (spec -17 VDC) and -25.1 VDC (spec -24 VDC) but seem reasonable.

My concern is that it appears someone modified the reproduce amp by adding 9.2k ohm resistors in series (after) the 20 uF input capacitors - first photo. Second photo shows the stock board. They also added 470 pF capacitors between the base and the emitter of the first transistor in signal path - 5Q1 (schematic attached) . . . not sure what that is for. Seems to me that the added resistor would be the likely cause of the low output.

470 pF capacitors have also been added to the record amplifier boards between the base and emitter of 6Q1 - the first transistor in the signal path (schematic attached).

My plan is to return the boards to their original configuration, but thought i'd check with everyone here to see if these modifications were done for a good reason and if the voltages seem OK..

Rich

 

[KentTeffeteller]

I'd take the Magnecord back to stock. That model was very well designed and engineered in the era. Nothing wrong with one which is in excellent stock working order.

 

[Richard P]

Thanks for the feedback. I'll return it to stock

 

[Richard P]

Now another question - The reproduce and record cards have electrolytic caps that I assume should be replaced as some point. How about the ceramic caps? I believe i've read that ceramic caps should be replaced in audio circuits like these. The one I checked out of circuit was a 3.3 nF ceramic disk that measured 2.4 nF. Does it matter what type i replace them with as long as the values match the original spec? What about voltage rating? Maybe not a concern on these cards . . .