Scott 99C - No more sound
- Thread starter havols
- Start date
havols
Well-Known Member
Hi.
I reinstall the output TAP.
I replaced again the C1A; B; C; D, C2 C3A and C3B.
Checked the R54 A, B, C, and all readings OK.
I take out all positive wires from each capacitor by time, and the short signal (Dim Bulb Shines strong) stills.
The only way to B+ increase, and short signal on dim bulb test disappear, is when i take out the 390V red wire to output TAP.
So. I am tired. I can't find the problem, for now. I think, i will to rest for a few days, by this scott...
thanks for help.
I reinstall the output TAP.
I replaced again the C1A; B; C; D, C2 C3A and C3B.
Checked the R54 A, B, C, and all readings OK.
I take out all positive wires from each capacitor by time, and the short signal (Dim Bulb Shines strong) stills.
The only way to B+ increase, and short signal on dim bulb test disappear, is when i take out the 390V red wire to output TAP.
So. I am tired. I can't find the problem, for now. I think, i will to rest for a few days, by this scott...
thanks for help.
havols
Well-Known Member
I'm back
I will try once again to fix the problem of my scott 99c. I want to listen my lps on it again.
I'm no expert. Everything I know I learned here in AK. Thanks to all who have helped me so far in this thread and others.
Well. Let's to the facts. All large electrolytic capacitors was replaced, and all with negative tip on chassis.
I removed all the tubes, except the rectifier tube. Now it is only with the rectifier tube. When I switch it on with Dim Bulb Test, there is a small short circuit signal. I already replace the rectifier tube with a good one, and the problem continues.
Yesterday I decided to put it on without the dim bulb test, to see what would happen. Well, the B + was at 208VDC and stoped there. I heard a great noise in the speaker. R54 B overheated, and smoke began to flow out of it. I replaced the R54B and R54C with new ones, and the problem persisted. The readings of R54A is with the schematic.
When I disconnect the RED Wire from output tap, the problem of the short disappears.
The primary impedances from Output tap seems to be Fine. 183ohm and 159ohm.
I did the continuity test on primaries of output tap.
Red wire to Push-pull 1: 255
Red wire to push-pull 2: 292
Well ... here I am. If anyone can help me identify the problem, I will be very grateful
Regards
I will try once again to fix the problem of my scott 99c. I want to listen my lps on it again.
I'm no expert. Everything I know I learned here in AK. Thanks to all who have helped me so far in this thread and others.
Well. Let's to the facts. All large electrolytic capacitors was replaced, and all with negative tip on chassis.
I removed all the tubes, except the rectifier tube. Now it is only with the rectifier tube. When I switch it on with Dim Bulb Test, there is a small short circuit signal. I already replace the rectifier tube with a good one, and the problem continues.
Yesterday I decided to put it on without the dim bulb test, to see what would happen. Well, the B + was at 208VDC and stoped there. I heard a great noise in the speaker. R54 B overheated, and smoke began to flow out of it. I replaced the R54B and R54C with new ones, and the problem persisted. The readings of R54A is with the schematic.
When I disconnect the RED Wire from output tap, the problem of the short disappears.
The primary impedances from Output tap seems to be Fine. 183ohm and 159ohm.
I did the continuity test on primaries of output tap.
Red wire to Push-pull 1: 255
Red wire to push-pull 2: 292
Well ... here I am. If anyone can help me identify the problem, I will be very grateful
Regards
FlaCharlie
Super Member
OK, I'm hesitant to comment since I have not read the entire thread, but only the last several posts. And, I admit, I myself hate it when I see people comment on threads they haven't read. Be that as it may . . .
Despite whatever readings you're getting I'd suspect a bad OT. To test this I'd find another PP OT, connect it and see if you still have a short.
Don't worry about it if it's not the correct specs for the amp. You're not going to actually run the amp with it installed. It's just there for testing purposes.
FlaCharlie
Super Member
Sure, just tape off the UL connection.
I believe he said that the short occurs with all the tubes, except the rectifier, removed.
