Thanks for the heads up, I'll check it out.martin manning wrote: ↑Sun May 26, 2024 4:33 pmI made a small tweak to the eyelet board .pdf on this. Increased the current limiter to 47R, and decreased the bleeder to 150k. Should have it drained in a minute or so.
Search found 347 matches
- Mon May 27, 2024 12:46 am
- Forum: Dumble Discussion
- Topic: A SSS Build
- Replies: 54
- Views: 2013
Re: A SSS Build
- Sat May 25, 2024 2:35 am
- Forum: Dumble Discussion
- Topic: A SSS Build
- Replies: 54
- Views: 2013
Re: A SSS Build
Hope that solves it! The speaker output should be in phase with the PI input. Yours will be the first with the new resistors added to the bipolar supply. I’ll be interested to hear how that works in hardware. It did fix the problem, thanks. The bleeder is definitely a good idea. The +170 volt caps ...
- Fri May 24, 2024 3:00 am
- Forum: Dumble Discussion
- Topic: A SSS Build
- Replies: 54
- Views: 2013
Re: A SSS Build
Found a problem. Hopefully the problem. Circled 270k should be 270r. Voltages on V6 are much higher than on Viperdoc's schematic. Will work on this more tomorrow.
- Fri May 24, 2024 12:27 am
- Forum: Dumble Discussion
- Topic: A SSS Build
- Replies: 54
- Views: 2013
Re: A SSS Build
I've been working on an oscillation. It's only in the power section, from the PI to speakers. Goes away if feedback from speaker is disconnected. First three of the below are Channel 1: 8 ohm dummy load; Channel 2: PI (V6) Pin 6. 400 hz signal. 8 ohm dummy load. Refer to Viperdoc's schematic . Pic 1...
- Thu May 23, 2024 3:51 pm
- Forum: Dumble Discussion
- Topic: A SSS Build
- Replies: 54
- Views: 2013
Re: A SSS Build
Completed installation of bipolar power supply. Amp is now working again with better B+ and other voltages. Question: with the decreased voltage the bipolar supply provides V7 does this limit the clean headroom? Volume? Is there a noticeable tonal difference between the original and bipolar supplie...
- Thu May 23, 2024 4:41 am
- Forum: Dumble Discussion
- Topic: A SSS Build
- Replies: 54
- Views: 2013
Re: A SSS Build
Completed installation of bipolar power supply. Amp is now working again with better B+ and other voltages. When plugging in 8 ohm dummy load had a déjà vu moment. I used Puretone jacks on the unswitched outputs because they have better contacts than Switchcraft. However they are a little harder to ...
- Wed May 22, 2024 8:47 pm
- Forum: Dumble Discussion
- Topic: A SSS Build
- Replies: 54
- Views: 2013
Re: A SSS Build
Sockets are how i see new.. and Belton, so means high quality.. Never failed any in my life. So there is only 0.1% of chance that sockets are a problem.. Probably output tubes.. Yes brand new Belton sockets. I found nothing wrong, no signs of tracking and no residual carbon from the resistors that ...
- Wed May 22, 2024 8:41 pm
- Forum: Dumble Discussion
- Topic: A SSS Build
- Replies: 54
- Views: 2013
Re: A SSS Build
This is bad tube problem.. pls measure resistance directly on the tube pins, between 2-3. Using a Fluke 87 DMM, one tube has no continuity on any pin to any other pin (open heater). The other three only have continuity from pins 2 to 7 (heaters), no other pins have continuity to any other pins. I'm...
- Wed May 22, 2024 3:21 am
- Forum: Dumble Discussion
- Topic: A SSS Build
- Replies: 54
- Views: 2013
Re: A SSS Build
Once you have an arc occur there may be carbon tracking on the tube sockets which must be completely removed to prevent more arcing. If the socket material has been burned, replacing the socket may be necessary. So what caused the initial arcing? I think it was most likely an oscillation in the pow...
- Tue May 21, 2024 11:52 pm
- Forum: Dumble Discussion
- Topic: A SSS Build
- Replies: 54
- Views: 2013
Re: A SSS Build
Spent the morning putting a PT from Mojotone in. Now the B+ is 458vdc in standby. Put it to Operate and saw a MAJOR arc in V8 and inside the amp at the same time. V8 heater opened and evidently shorted to B+. Cut the power immediately. Both 100 ohm heater to ground resistors smoked. Replaced 100 ohm...
- Tue May 21, 2024 9:47 pm
- Forum: Dumble Discussion
- Topic: A SSS Build
- Replies: 54
- Views: 2013
Re: A SSS Build
Hi Glenn Apologies if this is me being stupid. Given that the #102 is providing 428V with a 340-0-340 @400mA PT isn't it reasonable you'd get the lower B+ reading of 414V from the 320-0-320 @450mA PT in the SSS with the same wall voltage? Could it be the higher 440V reading you noted was taken unde...
- Tue May 21, 2024 1:40 pm
- Forum: Dumble Discussion
- Topic: A SSS Build
- Replies: 54
- Views: 2013
Re: A SSS Build
I had the same problem in one amp, when inside the box.. chassis and power transformer were extremelly hot.. while outside on the table, chassis and PT temp was just moderate, nothing to worry about... Then i discover that there is no sufficient air circulation in the cabinet, and tubes were heatin...
- Tue May 21, 2024 2:11 am
- Forum: Dumble Discussion
- Topic: A SSS Build
- Replies: 54
- Views: 2013
Re: A SSS Build
102 amp is still on, Operate, idle-no input. Transformer is very warm, I can only keep my fingers on it for 2-3 seconds. Similar in temperature to SSS transformer. This is after nearly 4 hours operation.
- Mon May 20, 2024 10:22 pm
- Forum: Dumble Discussion
- Topic: A SSS Build
- Replies: 54
- Views: 2013
Re: A SSS Build
I just checked voltages on my 102 w/built in Dumbleator that has basically same PT and 6L6 power tubes.
B+ in operate is 428vdc
Power tubes biased to 42mA
Wall voltage 119vac
Secondary voltages in operate 333-67-0-333vac
Hasn't been on long enough for PT to reach stable temperature.
B+ in operate is 428vdc
Power tubes biased to 42mA
Wall voltage 119vac
Secondary voltages in operate 333-67-0-333vac
Hasn't been on long enough for PT to reach stable temperature.
- Mon May 20, 2024 8:45 pm
- Forum: Dumble Discussion
- Topic: A SSS Build
- Replies: 54
- Views: 2013
Re: A SSS Build
I only have one fuse, 3 amp slow on input power.
In Operate
118vac wall voltage
320-0-322 vac secondary. 320vac leg is also feeding bias circuit.
B+ 414vdc
Bias -360vdc at 5mA
PT's biased to 27mA with -49 volts.
In Operate
118vac wall voltage
320-0-322 vac secondary. 320vac leg is also feeding bias circuit.
B+ 414vdc
Bias -360vdc at 5mA
PT's biased to 27mA with -49 volts.