03-21-2018, 02:18 PM
OK I promise this is last one, then it's back to hollow state.. Anyway I don't have another worthy of mention..
I've had this 1958 P-746A for probably 20 years but till yesterday it's never played a note.. Clean, apparently seen little usage..
After posting about the newer(1959) P-806A in the other GE thread I was fired up to repair it..
Replacing the electrolytics restored audio amp operation, otherwise still nothing.. Naturally not a easy one, found osc dead, voltages in ballpark.. I pulled xistor and checked with ohm meter, seemed OK.. Resistors all OK, caps mostly ceramic disc that I refuse to change.. I dig out the B&K xistor checker.. It's dead.. Arghhh... Got it open and found one of the P/S electrolytics shorted, replaced that, wa-la it's working(next in line for recap).. Checked transistor and found it somewhat leaky, approx 1.5X over allowable..
Naturally out of probably 500 ECG, SK, GE etc replacements, I don't have a low power RF germanium NPN on hand(several PNP).. OK since I had to be in Norfolk yesterday, I swung by the the only distributor remaining in area.. Well NTE 101 has such a limited calling these days, they don't have it.. BUT do have a 2N1994 that crosses to 101 and if I want that, its 50 cents!! Sure why not??
With the new xistor it sprang to life..
Chassis just before reassembly, new transistor in upper right, beside osc coil
[attachment=15802]...
Leaky 2N168A transistor and old caps, out of six one was still good
[attachment=15803]
Back together and playing tunes...
[attachment=15804]
I've had this 1958 P-746A for probably 20 years but till yesterday it's never played a note.. Clean, apparently seen little usage..
After posting about the newer(1959) P-806A in the other GE thread I was fired up to repair it..
Replacing the electrolytics restored audio amp operation, otherwise still nothing.. Naturally not a easy one, found osc dead, voltages in ballpark.. I pulled xistor and checked with ohm meter, seemed OK.. Resistors all OK, caps mostly ceramic disc that I refuse to change.. I dig out the B&K xistor checker.. It's dead.. Arghhh... Got it open and found one of the P/S electrolytics shorted, replaced that, wa-la it's working(next in line for recap).. Checked transistor and found it somewhat leaky, approx 1.5X over allowable..
Naturally out of probably 500 ECG, SK, GE etc replacements, I don't have a low power RF germanium NPN on hand(several PNP).. OK since I had to be in Norfolk yesterday, I swung by the the only distributor remaining in area.. Well NTE 101 has such a limited calling these days, they don't have it.. BUT do have a 2N1994 that crosses to 101 and if I want that, its 50 cents!! Sure why not??
With the new xistor it sprang to life..
Chassis just before reassembly, new transistor in upper right, beside osc coil
[attachment=15802]...
Leaky 2N168A transistor and old caps, out of six one was still good
[attachment=15803]
Back together and playing tunes...
[attachment=15804]