Search found 503 matches
- Wed Jan 18, 2023 8:15 pm
- Forum: Fender Discussion
- Topic: AB763 Stunflower
- Replies: 49
- Views: 10938
AB763 Stunflower
Having never built or played a classic black face Fender, I decided to build one for my next project. I like amps in the 50 watt range so I decided to build a vibroverb in a head cabinet. The schematic I'm using is below. Like many of us, I could not resist the chance to tinker with the circuit a bi...
- Fri Jan 06, 2023 6:29 pm
- Forum: Technical Discussion
- Topic: latest amp build
- Replies: 5
- Views: 883
Re: latest amp build
Pretty cool! It has gotta feel good to see something you no doubt spent many many hours drawing up become reality.
Are the four fuses for the PT HV secondaries and heaters?
Mike
Are the four fuses for the PT HV secondaries and heaters?
Mike
- Mon Jan 02, 2023 9:06 pm
- Forum: Marshall Discussion
- Topic: marshall sv20h hand wired clone
- Replies: 4
- Views: 2799
Re: marshall sv20h hand wired clone
Why not just build a 50w 1987? It would probably be cheaper and easier to find transformers for a 1987 than the 20 watt thing. The 50 watter would only be a few decibels louder than the 20 watt. And neither one would really be a bedroom amp (even at 5 watts). For sure a hand built 1987 would be a ni...
- Tue Dec 20, 2022 6:38 pm
- Forum: Garage Talk
- Topic: Mortality - Some Thoughts
- Replies: 31
- Views: 4932
Re: Mortality - Some Thoughts
No one close to me has any idea what they are or their market value (collectively maybe a couple of thou'?) I've also got a couple of 60's Gibson amps, which, in some circles, have almost achieved sub-boutique status. I'm not ready to part with my toys. Not yet. Seriously, I don't want them to end ...
- Mon Dec 19, 2022 9:22 pm
- Forum: Trainwreck Discussion
- Topic: UPDATE: Finished my Express build last night > it's working!
- Replies: 81
- Views: 19847
Re: UPDATE: Finished my Express build last night > new PT, no more fuses blowing, odd output
I took the volume pot out of the circuit and it tested 1M but I’ll definitely test the treble pot as well. For what it’s worth, the tone controls affect the sound coming through the speakers. If you tested the pot just end to end for being near 1M *also* test out the center wiper. If this connectio...
- Mon Dec 19, 2022 5:45 pm
- Forum: Trainwreck Discussion
- Topic: UPDATE: Finished my Express build last night > it's working!
- Replies: 81
- Views: 19847
Re: UPDATE: Finished my Express build last night > new PT, no more fuses blowing, odd output
... Removing bright switch removes all signal Bypassing tone stack removes signal ... The two bolded items consfuse me, but maybe they help narrow down where things are getting dumped? Yea. These are two new bits of information. Your volume pot may be bad and/or the ground connection to the volume ...
- Sat Dec 17, 2022 11:49 pm
- Forum: Trainwreck Discussion
- Topic: UPDATE: Finished my Express build last night > it's working!
- Replies: 81
- Views: 19847
Re: UPDATE: Finished my Express build last night > new PT, no more fuses blowing, odd output
Do you have a smart phone with a headphone jack? If so, you can make a crude signal generator with it, a coupling capacitor and a cable. There are many signal/function generators out there for smart phones. Most are free downloads. Then rig up a cable from the headphone out with one of the positive ...
- Fri Dec 16, 2022 7:19 pm
- Forum: Trainwreck Discussion
- Topic: UPDATE: Finished my Express build last night > it's working!
- Replies: 81
- Views: 19847
Re: UPDATE: Finished my Express build last night > new PT, no more fuses blowing, odd output
It is a common thing to miswire the input jack so that the incoming guitar signal does not have a ground reference and is floating. This might cause what you are hearing. With the amp off and an instrument cable pugged into the input, measure the resistance from the tip of the cable to the chassis. ...
- Fri Dec 16, 2022 4:28 am
- Forum: Trainwreck Discussion
- Topic: UPDATE: Finished my Express build last night > it's working!
- Replies: 81
- Views: 19847
Re: UPDATE: Finished my Express build last night > new PT, no more fuses blowing, odd output
This is sorta a scientific wild a$$ guess based on it being quite and muffled. Maybe the tone stack is not wired correctly and or has a bad pot or something. Try lifting the tone stack out of the circuit by disconnecting the mid pot from the ground buss. Does that change anything?
Mike
Mike
- Tue Dec 13, 2022 3:11 am
- Forum: Garage Talk
- Topic: Too stupid for tech sections! (clipping madness!)
- Replies: 4
- Views: 1046
Re: Too stupid for tech sections! (clipping madness!)
Nice! For posterity, you should post some sound clips! :) I need to bust out some trimmers and play around in my 4 stage SIR #39 type thing. I like the idea of trimmers on the cathodes balance the clipping. I think this is is how the SLO ended up with a 39k cathode resistor. He was trying to make it...
- Sun Dec 11, 2022 3:34 am
- Forum: Technical Discussion
- Topic: GZ34S vs 5U4GB --- voltage drop question, plus a discussion of SS diodes as backup
- Replies: 17
- Views: 1356
Re: GZ34S vs 5U4GB --- voltage drop question
I strongly recommend putting a FRED in series with each rectifier tube anode. This has essentially zero effect if the tube is operating normally, but if the rectifier shorts, the FRED stops the first filter cap or the PT from dying. A few questions about putting diodes in series with a tube rectifi...
- Sat Dec 03, 2022 6:03 am
- Forum: Trainwreck Discussion
- Topic: UPDATE: Finished my Express build last night > it's working!
- Replies: 81
- Views: 19847
Re: Finished my Express build last night, odd voltage issues (fuses blowing)
Unless I missed something (which is always possible :), it looks like your power supply has no shorts to ground all the way to V1. But something is drawing excessive current and taking out the mains fuse when you go off the limiter. How bright is the bulb when on the limiter and no power tubes? It s...
- Sat Dec 03, 2022 2:46 am
- Forum: Trainwreck Discussion
- Topic: UPDATE: Finished my Express build last night > it's working!
- Replies: 81
- Views: 19847
Re: Finished my Express build last night, odd voltage issues (fuses blowing)
Pull the output tubes and plug the AC cord straight into the wall outlet. Recheck the voltages on the power tubes. Those readings are with no power tubes. And if I plug straight to the wall, I blow a fuse. Just to clarify the situation. Does the fuse blow when plugged straight into the wall with *o...
- Fri Dec 02, 2022 6:39 pm
- Forum: Trainwreck Discussion
- Topic: UPDATE: Finished my Express build last night > it's working!
- Replies: 81
- Views: 19847
Re: Finished my Express build last night, odd voltage issues (fuses blowing)
I took some voltage readings around the circuit. Numbers in parentheses are with the standby switched off (to the "operate" position). C21 + side: 0v C21 - side: -35v C22 + side: 0 C22 - side: -28 /// Without knowing which layout/schematic these R and C numbers refer to, it is difficult or impossib...
- Fri Dec 02, 2022 6:14 am
- Forum: Trainwreck Discussion
- Topic: UPDATE: Finished my Express build last night > it's working!
- Replies: 81
- Views: 19847
Re: Finished my Express build last night, odd voltage issues (fuses blowing)
I redid my entire PS section and I’m still blowing fuses (the indicator bulb blows too when I turn it on, no tubes). When I run it through the voltage limiter, everything fired up fine, but straight into the wall, poof. Carefully measure some voltages while it is on the limiter and post them. That ...