SX-1980 Recap Assistance
- Thread starter bbauer01
- Start date
bbauer01
Active Member
Thank you for looking. I ordered one similar to the factory heatsink.
bbauer01
Active Member
Thank you EchoWars. I received the current source boards today. They are awesome... thank you for the prompt response.
With how much I have to do to make this board right, I am starting with the worst and working from there. So far, the -80v side is done. Had to add in a .047uf / 150v ceramic in location c229, correct a cut trace, and remove the remainder of the old current source circuit. Measured at -81v operating. Hopefully, the +80v side will go as smooth, tomorrow evening.
With how much I have to do to make this board right, I am starting with the worst and working from there. So far, the -80v side is done. Had to add in a .047uf / 150v ceramic in location c229, correct a cut trace, and remove the remainder of the old current source circuit. Measured at -81v operating. Hopefully, the +80v side will go as smooth, tomorrow evening.
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anderslober
Yikes...not again!
That looks great! EW...do those great looking current source boards come with mounting instructions? EDIT: I found the paper thread with all the info...thanks Glenn.
Keep the great pictures and info comin' bbaur01..........great!.
Keep the great pictures and info comin' bbaur01..........great!.
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anderslober
Yikes...not again!
Glenn... PM sent.
bbauer01
Active Member
I had the document with the updated schematic (posted in other threads and posted as a link in this thread by MarkTheFixer), which very nicely detailed how they should go in the circuit. On the next one, I may stand it up, since space might not be on my side.
anderslober
Yikes...not again!
bbauer01
Active Member
I got everything done and I will post pictures later tonight. The power supply board was done in steps. First I installed the EW current sources and then tested. Then I recapped and tested. Then I replaced the transistors and now I am having an issue. All of the function lights are dim, and FM doesn't seem to do anything. What did I mess up now?
Pin 17 = +80.5
Pin 9 = +35.7
Pin 8 = -31.8
Pin 11 = -37.3
Pin 18 = -84.4
Pin 7 = +12.8
Pin 13 = +7.2 (Low - should be 13.5)
Pin 14 = +7.2 (Low - should be 13.5)
Pin 15 = +2.6 (should be 5.0) <= This should be resolved when I get 13.5v on pin 13,14
Pin 16 = + 3.9 (should be 8.0) <= This should be resolved when I get 13.5v on pin 13,14
Pin 17 = +80.5
Pin 9 = +35.7
Pin 8 = -31.8
Pin 11 = -37.3
Pin 18 = -84.4
Pin 7 = +12.8
Pin 13 = +7.2 (Low - should be 13.5)
Pin 14 = +7.2 (Low - should be 13.5)
Pin 15 = +2.6 (should be 5.0) <= This should be resolved when I get 13.5v on pin 13,14
Pin 16 = + 3.9 (should be 8.0) <= This should be resolved when I get 13.5v on pin 13,14
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Uncle Bambi
Funky Tut
If the problem presented after you replaced the transistors, that's where I'd start. That 13 volts need to be there, as I learned when I got help fixing my SX-838. In my case it was a bad transistor on the 13 volt path in the phono amp board.
Go for low-hanging fruit - are the new one's oriented correctly, are they the right ones in the right place, etc. One of The Great One's should be along shortly to give you better assistance, but in the meantime that's where I'd look....
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bbauer01
Active Member
Agreed. Tracing things out following the schematic, I find that everything is good up until q201. Service manual states I should expect 14.7v at the base and 14.1v at the emiter. I have:
q201
B = 8.1v
E = 7.2v
C = 29v
detail which transistors replaced q201, q202, q203.
also what YOU think their lead arrangements are.
then all their voltages.
also what YOU think their lead arrangements are.
then all their voltages.
bbauer01
Active Member
q201 ztx694b - CBE
C = 29v
B = 8.1v
E = 7.2v
q202 ztx694b - CBE
C = 8v
B = 3.6v
E = 7.9v
q203 MJE15032g - BCE
B = 7.8v
C = 30.2v
E = 7.3v
what is special / different about the zetex transistor bodies??
to identify lead locations? how many zetexes have you replaced on this board?
to identify lead locations? how many zetexes have you replaced on this board?
bbauer01
Active Member
Flat side down, leads are: CBE, which isn't the standard lead arrangement for a TO-92 cased device. I replaced all TO-92s on that board with the zetexes and all the TO-220s with ON semi devices.
Replace Q202, be sure the leads are correct. This one's readings are weird, maybe it can't turn on hard enough. D207 is starved for current thus the higher voltage. Check all the resistors,
r201,turnon current
r204, zener
r205, r206 1/2 voltage divider
as well as r230 and d216?
all with one leg lifted.
r201,turnon current
r204, zener
r205, r206 1/2 voltage divider
as well as r230 and d216?
all with one leg lifted.
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bbauer01
Active Member
Thanks Mark.
Q202 is fine. I replaced it earlier.
R201 is fine. Measured at 22k Ohm. When I was measuring earlier today, I verified the other side has 80v.
R204 is fine. Measured at 2.4k Ohm.
D207 Zener is bad?? Why?? I didn't even touch it and everything else is right... grrr Measured .6v forward and 1.1v reverse
Will replace with (next Mouser order): 512-1N5234B Fairchild 6.2V, 0.5W Zener
R205 is fine. Measured at 1.34k Ohm
R206 is fine. Measured at 1.21k Ohm
R230 is fine. Measured at 110 Ohm
D216 is fine. .6v forward. 0 reverse.
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bbauer01
Active Member
I found a suitable zener in a parts sx-780 that I had. Once I tested it, I put it in the 1980 and everything is good now.
I can't seem to find my picture after all the transistors were replaced and relocated, but here is a pic of the power supply board with all new caps (but one) and the EW current source boards.
Recapped amp board
I can't seem to find my picture after all the transistors were replaced and relocated, but here is a pic of the power supply board with all new caps (but one) and the EW current source boards.
Recapped amp board
bbauer01
Active Member
Here is the power supply board complete and operating. I tried to take EchoWars advice and get the axial caps as far away from the large heatsink as possible, which is why they aren't centered.
The second pic shows my replacement heatsinks, since I didn't have the originals due to the transistors being relocated. Any comments or thoughts on the replacement heatsinks... other than the fact that I made a mess with thermal grease (now cleaned up)?
The second pic shows my replacement heatsinks, since I didn't have the originals due to the transistors being relocated. Any comments or thoughts on the replacement heatsinks... other than the fact that I made a mess with thermal grease (now cleaned up)?
What I had posted was that I used a radial cap to replace the original 220µf 160V axial caps, and oriented them so that there was as much space as possible between them and the heatsink. With the big axial caps, there's no choice but to mount them & lament the fact that Pioneer screwed the pooch with this design.