Search found 342 matches
- Thu May 23, 2024 4:41 am
- Forum: Dumble Discussion
- Topic: A SSS Build
- Replies: 45
- Views: 1239
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: 45
- Views: 1239
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: 45
- Views: 1239
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: 45
- Views: 1239
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: 45
- Views: 1239
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: 45
- Views: 1239
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: 45
- Views: 1239
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: 45
- Views: 1239
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: 45
- Views: 1239
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: 45
- Views: 1239
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.
- Mon May 20, 2024 4:50 pm
- Forum: Dumble Discussion
- Topic: A SSS Build
- Replies: 45
- Views: 1239
Re: A SSS Build
Does anyone know if Heyboer will rewind one of their transformers for a fee? I’m thinking it would probably be cheaper to buy a new one. Interested to know if you find out. I agree it would likely be more. More work because they must remove the old windings and disassemble core prior to winding. I ...
- Mon May 20, 2024 2:39 pm
- Forum: Dumble Discussion
- Topic: A SSS Build
- Replies: 45
- Views: 1239
Re: A SSS Build
Great looking build Glenn - your son is lucky indeed. Does the PT get that hot in standby? I wonder if the PT buzzing earlier on in your process was more sinister than it seemed. Mine doesn’t run hot, but is a 2x6L6 with tremolux iron. Might be worth tracking your wall voltage too, just in case tha...
- Sun May 19, 2024 3:09 am
- Forum: Dumble Discussion
- Topic: A SSS Build
- Replies: 45
- Views: 1239
Re: A SSS Build
Replaced rectifier diodes, no change in how it acts. B+ back up to 420vdc range with +/-2vdc drift. Transformer too hot to touch more than a few seconds, maybe 110°F to 120°F. PT's biased to ~15watts (36 mA @ 420 volts). Isolated and checked 47uF 500v caps before Standby switch. Both test 50uF and 1...
- Sat May 18, 2024 8:39 pm
- Forum: Dumble Discussion
- Topic: A SSS Build
- Replies: 45
- Views: 1239
Re: A SSS Build
Here's the B+ ripple.
- Sat May 18, 2024 8:27 pm
- Forum: Dumble Discussion
- Topic: A SSS Build
- Replies: 45
- Views: 1239
Re: A SSS Build
B+ is now down to 411vdc in Operate. Voltage out of PT is still 320-0-320vac. I think this rules out the PT as issue. Rectifiers? I used UF4007, 6 of them. I've got plenty so will replace them.
I'm open to suggestions.
I'm open to suggestions.