TX-7500 Tuning procedure

[kasbah512]

Any advice on tuning this device? the left channel is probably half volume out of the fixed volume RCA connection, and the max signal indicates the balance slightly to the right side. Variable output has static, but this is likely due to the 2sa725 transistors i have yet to change out.

I'm wondering if i could make an adjustment by ear, without throwing everything out of wack. I don't have an oscilloscope yet, but i doubt it would be of much use as there is no manual i can find for this unit.

 

[markthefixer]

Until you have cleaned and deoxited it, and gotten rid of all the 2sa725 & 2sc1344 transistors making adjustments would be ill-advised.

patience...


and for deoxiting, an ohmmeter should be used to verify the contact resistance and it's repeatability.

Frequency response of circuits CAN be affected by too much contact resistance.

 

[kasbah512]

Until you have cleaned and deoxited it, and gotten rid of all the 2sa725 & 2sc1344 transistors making adjustments would be ill-advised.

patience...


and for deoxiting, an ohmmeter should be used to verify the contact resistance and it's repeatability.

Frequency response of circuits CAN be affected by too much contact resistance.

Fair enough. It was well cleaned around a year ago, but i haven't messed with it much since. I ordered it off ebay 2 years ago in "working" order, but it appears it hasn't been serviced since the 1980's. I have some KSA992 and KSC1845 laying around i can throw in there. I already have the capacitors to do a full swap. I suppose ill dive into it later today. I don't have the spray deoxit, but i do have a small vial of some red deoxit on hand, and some plain old contact cleaner. Ill try these suggestions out and see how its sounding.