I used 30.
SX-1980 rescue
- Thread starter Overundr1
- Start date
It's Aliveeeeeeeeeeee 
After checking on the dim bulb tester I fired the old gal up. One click, about 7 seconds later the second click and we have a working 1980 once again. Poor thing, been discarded for over a decade and told not worth repairing. Still have to dis assemble the faceplate and give her a good deoxit bath since the controls are pretty noisy. I do have a couple of questions though. Offset could not be brought from @-50mv on either channel. Both channels have bias set to 40mv, again about as low as I could get them. Manual indicates remove jumpers B (left) and D (right) and re-adjust. Where are those two jumpers? Otherwise why would offset be slightly (-) and not coming to zero. Second observation, the regulator board does run hot with most of the heat seeming to arise from Q203. Once I get that sorted out I will get her up on my scope and check for oscillation. Not a true beauty yet but could not resist showing her off.
-Lee
After checking on the dim bulb tester I fired the old gal up. One click, about 7 seconds later the second click and we have a working 1980 once again. Poor thing, been discarded for over a decade and told not worth repairing. Still have to dis assemble the faceplate and give her a good deoxit bath since the controls are pretty noisy. I do have a couple of questions though. Offset could not be brought from @-50mv on either channel. Both channels have bias set to 40mv, again about as low as I could get them. Manual indicates remove jumpers B (left) and D (right) and re-adjust. Where are those two jumpers? Otherwise why would offset be slightly (-) and not coming to zero. Second observation, the regulator board does run hot with most of the heat seeming to arise from Q203. Once I get that sorted out I will get her up on my scope and check for oscillation. Not a true beauty yet but could not resist showing her off.
-Lee
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anderslober
Yikes...not again!
Excellent! Darn beaut' , you have there! Please keep posting....with pics too
Uncle Bambi
Funky Tut
It's Aliveeeeeeeeeeee
After checking on the dim bulb tester I fired the old gal up. One click, about 7 seconds later the second click and we have a working 1980 once again.
Way to go!
I've been following this thread closely - entertaining, informative, well chronicled.... it is a real AK treasure trove - thanks for taking the time to post your excellent pictures and descriptions.
DaWoofer
Super Member
Thanks for the great pics as I believe many will use this thread in the future. I might be if I don't get that call from a certain member (hint, hint.) I don't mind fiddling inside my lower grade receivers but I think I'll leave this one to a qualified individual with many more years experience than me since i plan on keeping mine in the family for many more decades.
Glad to hear yours is finally up and singing, it must feel real good to be at this point in the restoration!
Glad to hear yours is finally up and singing, it must feel real good to be at this point in the restoration!
DaWoofer
Super Member
Looking at the schematic it seems this receiver has many more circuits than many others out there. Pioneer added things to this one that there other TOTL do not have I believe. They were going all out on some things the way it looks. How much better they are than others only these experienced techs might know. Me, I don't understand much of their purposes or advantages over other competition.
hrballenger
Well-Known Member
Great Job, Congratulations !!! And a great job of documenting your journey. I love these old beauties ( had mine since new ) and need to go through mine and do the power board updates and recaps at some point.
It's Aliveeeeeeeeeeee
After checking on the dim bulb tester I fired the old gal up. One click, about 7 seconds later the second click and we have a working 1980 once again. Poor thing, been discarded for over a decade and told not worth repairing. Still have to dis assemble the faceplate and give her a good deoxit bath since the controls are pretty noisy. I do have a couple of questions though. Offset could not be brought from @-50mv on either channel. Both channels have bias set to 40mv, again about as low as I could get them. Manual indicates remove jumpers B (left) and D (right) and re-adjust. Where are those two jumpers? Otherwise why would offset be slightly (-) and not coming to zero. Second observation, the regulator board does run hot with most of the heat seeming to arise from Q203. Once I get that sorted out I will get her up on my scope and check for oscillation. Not a true beauty yet but could not resist showing her off.
-Lee
While I have the other boards loose for a recap and deoxit I figured it was time to see if there was any luster left in the gal. Boy am I surprised, under that poor neglected skin appeared a beauty. Face clean and bright and a bonnet as purdy as all get out. Can't wait to get her all dressed up for showtime next week.
-Lee
-Lee
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Thinking out loud again over coffee this morning. Since Q203 2SD712 runs so hot I looked up the specs (100V 30W 55/300 HFE). It appears that the MJE 15032 (250V 50W 70HFE) would make a dandy replacement. Only issue I see is the size of the heat sink allowing enough thermal dissipation. I suppose it's not really an issue since both transistors are rated somewhere north of 125c degrees however still the fact that this receiver has a built in easy bake oven design for the regulator board still niggles at me a bit.
Starting to see the end of the road on this unit with only three boards left to recap and all the push button switches to get at and deoxit. Pics to follow as I work through them.
-Lee
Starting to see the end of the road on this unit with only three boards left to recap and all the push button switches to get at and deoxit. Pics to follow as I work through them.
-Lee
deoxit injection tool for pushbutton switch:
deoxit straw
couple of sizes of small heat shrink tubing
piece of 24 gauge solid insulated phone type wire. ~ 4 inches insulation left on 8" piece of wire
(I salvaged some from a length of cat-5 cable)
use heatshrink to couple straw to wire/insulation at insulation, some insulation still up straw.
edit - when making this, shave away a bit of the red plastic straw BEFORE the end under where the heat shrink will go, to help grip the shrink to the straw (smaller diameter a bit PLUS a lip to grip) - there's enough pressure squirt the whole shebang off.
careful not to melt wire insulation when shrinking
when all together, remove wire core leaving needle thin insulation with hollow core where wire was.
thread insulation through lower corner of spring, and into crack between switch plunger and switch body.
if careful, one can inject deoxit at the BACK of the switch..
deoxit straw
couple of sizes of small heat shrink tubing
piece of 24 gauge solid insulated phone type wire. ~ 4 inches insulation left on 8" piece of wire
(I salvaged some from a length of cat-5 cable)
use heatshrink to couple straw to wire/insulation at insulation, some insulation still up straw.
edit - when making this, shave away a bit of the red plastic straw BEFORE the end under where the heat shrink will go, to help grip the shrink to the straw (smaller diameter a bit PLUS a lip to grip) - there's enough pressure squirt the whole shebang off.
careful not to melt wire insulation when shrinking
when all together, remove wire core leaving needle thin insulation with hollow core where wire was.
thread insulation through lower corner of spring, and into crack between switch plunger and switch body.
if careful, one can inject deoxit at the BACK of the switch..
Attachments
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It sure has been a long and worthwhile journey with this project. I finished the recap except for the tuner board, set the offset to +/- 0mv on both channels, adjusted the bias to @40mv on both channels and let her run for an hour to settle in. Finished final checks before re-assembly and hooked up a cd player for her first real run. My oh my, need respect for the volume knob, this girl will bellow. With the tone board recapped and all the controls cleaned up she sings. Only thing I cannot do is align the FM board, however there are others who would do so if the real possessor of this girl is so inclined. I think I will go get a glass of ice tea and kick back for a while listening to her voice one more time before she has to go home. Thanks to all who offered tips and advice along the way, whose help, coaching and participation made this a trip to remember.
-Lee
-Lee
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AnalogChad
Never been cool.
Congrats! I've been following this post from the start and would love to see more pictures of the finished product.
