"100W" guitar amp that never worked from someone's custom build.
4 x 6L6
drew schematic front to back.
Major problem: one side of push pull drive not connected to 6L6 grids.
Another was bad ground connection point.
Final: 50-55 W at onset of clipping with 8R load.
4 x 6L6
drew schematic front to back.
Major problem: one side of push pull drive not connected to 6L6 grids.
Another was bad ground connection point.
Final: 50-55 W at onset of clipping with 8R load.
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Nice going DUG!
Home-brew stuff is always a challenge because it can't even be guaranteed to work from the design on forward.
Interesting stacks of equipment. You do guitar amps mostly?
-Chris
Home-brew stuff is always a challenge because it can't even be guaranteed to work from the design on forward.
Interesting stacks of equipment. You do guitar amps mostly?
-Chris
At least these days we have the benefit of LTSPICE etc.
When I were a young designer we did it on paper then built up a prototype on Veroboard.
One of my fellow engineers asked me to design a counter circuit to divide a crystal frequency. So I designed it and he went away.
A few days later he came back with a pcb and said it didn't work.
I asked if his prototype worked and he said what prototype !
The counter had been made from asynchronous counters so didn't work, it needed synchronous counters to work.
Too many smaller recent repairs to list, but most recent completed project is a repair and update to an Audio Research SP-4; new electrolytics, replaced some bad resistors, replaced all tantalums with high-quality electrolytics, general servicing.
Before that, repairs and update to 1 Apt Holman preamp and updates to 2 Apt Holmans, and repair of a hospital isolation transformer that was dropped in shipping. Metal work, plus parts replacement in that one!
Several projects currently underway.
Before that, repairs and update to 1 Apt Holman preamp and updates to 2 Apt Holmans, and repair of a hospital isolation transformer that was dropped in shipping. Metal work, plus parts replacement in that one!
Several projects currently underway.
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Those Holman preamps are nice and fun to work on.
Last year I had one, and among other issues, the mute button had a defective/broken "wink-eye" indicator inside it.
So, I modified it with a 3mm blue LED, which illuminated when on "mute".
The customer was thrilled with it.
The mute circuit/relay is sometimes a problem with those too.
A dimmer based soldering station I purchased from Lidl.
a) The soldering iron had a very low grade soldering tip. The claimed power was about 60W. I replaced the soldering iron with an Antex rated at 25W.
b) With repeated use it developed a loose contact and stopped working. On inspection I found the potentiometer has a bad contact and had to be replaced.
I have another soldering station from Lidl with temperature control, but I am doubtful about the quality of the soldering bits. I am mulling about how I can replace those bits with better quality bits while keeping the same heater and heat sensor.
a) The soldering iron had a very low grade soldering tip. The claimed power was about 60W. I replaced the soldering iron with an Antex rated at 25W.
b) With repeated use it developed a loose contact and stopped working. On inspection I found the potentiometer has a bad contact and had to be replaced.
I have another soldering station from Lidl with temperature control, but I am doubtful about the quality of the soldering bits. I am mulling about how I can replace those bits with better quality bits while keeping the same heater and heat sensor.
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I recently saw a piece of test equipment with these same indicators, but can't now recall what it was. Wonder if those are available anywhere. Your LED was a nice solution.
The relay problems I've come across with the Apt Holmans have been from the relays themselves. I replaced one with a smaller, higher-quality relay mounted on a perfboard.
I just burnish the contacts properly, never had a "callback" happen to this day.
My toenail.
I found that if you hit it just right, slightly under exactly the right thing, you can bend it back in such a way that it doesn't tear off, it remains attached to your foot and creates a sensation similar to electro-shock therapy. After the convulsions ceased, I headed to the bathroom before I was unable to from blood loss. I like donating blood just not to the floor, the carpet, the floor, the next carpet, the bathroom floor and finally the toilet. Didn't know I was such a bleeder till I started on Wafarin.
Repair something? Sure, Mother Nature will take of that, I just wanted someone to feel sorry for me.
Who better than you guys?
I found that if you hit it just right, slightly under exactly the right thing, you can bend it back in such a way that it doesn't tear off, it remains attached to your foot and creates a sensation similar to electro-shock therapy. After the convulsions ceased, I headed to the bathroom before I was unable to from blood loss. I like donating blood just not to the floor, the carpet, the floor, the next carpet, the bathroom floor and finally the toilet. Didn't know I was such a bleeder till I started on Wafarin.
Repair something? Sure, Mother Nature will take of that, I just wanted someone to feel sorry for me.
Who better than you guys?
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This was a special request.
Originally "give me the output tubes and you can have the rest"
Decided I could make it work after I drew out the schematic.
Payment was a guitar.
I don't play but need one in the house just in case.
🙂
I didn't repair my heat pump. The inside unit circulation fan bit the dust. I'm waiting on the repair man to fix it (parts warranty, no labor warranty). Hopefully tomorrow morning.
stupid center drain flat roof
water drip on 1st floor bathroom ceiling when it rains - its running down the waste pipe from the 3rd floor crawl space
the center drain iron pipe runs to the north side exterior wall where the rain/waste pipe and vent stack is
the clamp joining the iron down pipe to the pvc drain/waste pipe was leaking - I went with 10' of silicone self-fusing tape passed thru holes in the walls on either side of the join requiring 2 bodies, four hands
and there's still a drip running down from higher - probably the iron pipe angle fitting joints - behind more solid wood than I wanted to pull apart for now
I'll see what tonite's forecast 1-2" of rain shows about the relative size of the leaks - now that the walls are open
water drip on 1st floor bathroom ceiling when it rains - its running down the waste pipe from the 3rd floor crawl space
the center drain iron pipe runs to the north side exterior wall where the rain/waste pipe and vent stack is
the clamp joining the iron down pipe to the pvc drain/waste pipe was leaking - I went with 10' of silicone self-fusing tape passed thru holes in the walls on either side of the join requiring 2 bodies, four hands
and there's still a drip running down from higher - probably the iron pipe angle fitting joints - behind more solid wood than I wanted to pull apart for now
I'll see what tonite's forecast 1-2" of rain shows about the relative size of the leaks - now that the walls are open
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Very similar situation at one of our houses. Did you determine why the clamp leaked? In our case it was a faulty previous where the cast iron section was inadequately braced and the PVC section collapsed under the weight.
it was seeping right at the lower (PVC pipe side) band clamp screw assy but looked nominally OK - maybe some distortion underneath?
seems the heavy rain is missing me tonight
seems the heavy rain is missing me tonight
He
I feel your pain, sort of. My pinky finger recently went through something similar.
....almost 2 weeks ago I crushed my little fingertip when a large wooden post and a brick smashed together on it.....fingernail side towards the brick of course, meat was protruding through skin on the side, big slice through middle of the nail bed, crush fracture.
. Happened in evening just before dark. After bleeding slowed, and no longer feeling faint, I wrapped it up and drove to ER with fingernail partially attached to cuticle. Knew right away nail would be removed and that it was sew up job....
.
This is two days later......I will spare you what it looked like before.
😱
Stitches out this week, fingernail should grow back. Hopefully it will be repaired fully soon, although it may take some months for the nail.😛 And so it is, chalk up another scar for the hands.🙄
YIKES!! That's not good.
I feel your pain, sort of. My pinky finger recently went through something similar.
....almost 2 weeks ago I crushed my little fingertip when a large wooden post and a brick smashed together on it.....fingernail side towards the brick of course, meat was protruding through skin on the side, big slice through middle of the nail bed, crush fracture.
. Happened in evening just before dark. After bleeding slowed, and no longer feeling faint, I wrapped it up and drove to ER with fingernail partially attached to cuticle. Knew right away nail would be removed and that it was sew up job..... This is two days later......I will spare you what it looked like before.
😱Stitches out this week, fingernail should grow back. Hopefully it will be repaired fully soon, although it may take some months for the nail.😛 And so it is, chalk up another scar for the hands.🙄
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^ Ouch!
My last repair was today on an Autoclave. A hydraulic piston blew a seal, so I unhooked it and now we can just manually open and close the door, much easier anyway.. Don't ya just love hydraulic oil all over the floor, wall, fun times 🙂
My last repair was today on an Autoclave. A hydraulic piston blew a seal, so I unhooked it and now we can just manually open and close the door, much easier anyway.. Don't ya just love hydraulic oil all over the floor, wall, fun times 🙂