Check out this video for testing transistors.
https://youtu.be/KGcoOETCaEQ
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Printable View
Check out this video for testing transistors.
https://youtu.be/KGcoOETCaEQ
sent from Utah.
Well, I think I scared it back to barely working.
Read some stuff online and tried out a grounded vs groundless power connection. Grounded had the hum, groundless eliminated the hum when connected. Maybe a ground loop issue then? Tried to play music on it and got zero response.
Today I cracked it back open and checked all the transistors I could find, everything seemed to check out. Checked again for ac at the sub out with the rca shorted and nothing there. Reconnected it to a different receiver, no hum and I'm getting some music. Definitely quiet even with the gain cranked all the way up, but it's playing. Maybe an issue with the speaker itself?
It also may have noticed that I picked up a 12" sub at Costco for $170. That thing vibrated my balls nicely at 50% gain. Wife wanted me to turn it down within 30 seconds.
I still need a sub for another room and I like the enclosure for this one, so I'm not ready to give up yet.
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Nice. I like the persistance. Check the ohms of the speaker itself. Not sure if it should be 4 or 2, but something close to either of those (or 8, less likely) and it's probably ok. Try moving the cone in and out carefully, and see if there is any scraping in where the coil is.
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Not that. 8 ohms impedance per spec, 8 ohms on the reading. No obvious sounds of scraping or scratching either, but it's hard to exercise the cone. It's a downward firing sub with a plank below itQuote:
Originally Posted by basinbeater
https://uploads.tapatalk-cdn.com/202...f00e26e068.jpg
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Not sure how but these seem to keep showing up [emoji12]
Attachment 349337
Local guy made a good deal on this STR-7045 and some Realistic Nova 7bs. So old but it all still sounds so good. These 2 are well matched together.
Currently listening to the new King Gizzard on it.
I like the old Sony stuff. It was such high quality it was the stuff that laid the groundwork for the late 80s when Sony meant quality.
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Snagged a new project yesterday for cheap. Rotel rb-1090 power amplifier. 380 watts per channel rated at 8 ohms. A monster. Dual mono construction, with each channel getting a dedicated 1.2kva transformer and huge capacitance. One channel works ok, other is in protect. But the unit has seen better days, smells like ass, and news a refresh. Going to repair the bad board, put new caps throughout (except for the huge monster power supply ones.)
Should make for a pretty badass subwoofer amp, or turn a tidy profit. Fix it, play with it in the house, decide if it's a keeper or not. Thing is a goddamn beast!
I do have. Avery nice krell showcase 5 home theater amp if anyone is looking for the good stuff. Has had the proper input board capacitor repair to take care of a common failure point on these, as well all t channels having their bias adjusted. Mag deal @$1100.Attachment 351588Attachment 351589Attachment 351590Attachment 351591Attachment 351592
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Big caps.
Attachment 351594
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What are those rated for? Probably not a good idea to lick your finger and find out by feel!!
22,000uf 100v rated. Rail voltage on this sucker is like 96v. Big time power supply.
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Properly cleaned up and ready for supplying juice!
All the copper hardware and copper bars, and even that top plate is solid copper, easy to clean with a but of salt vinegar and a wire brush. Rinse, and dry. Attachment 351602Attachment 351603
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Clean......Attachment 351605
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My 70's Marantz 2238b made a series of super loud pops. Opened the case to find this. Hopefully the board is ok but there's some char. I can replace components but I'm not sure I'll be able to find a board if it's bad.
Thoughts?
Attachment 352909Attachment 352910
That sure looks to me like something was leaking out of the large capacitor. The transistor that scorcher the leak behind it may or may not be ok, doesn't look exploded. Have to get in there with a multimeter.
Second if there was large popping, you need to check the output transistors. Oh yeah, check the fuses. That thing needs a refresh
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Bought a non functional cd player yesterday for $10, just cause it was close to the rc car store. Tray was not working, it would open and immediately close. Fixed that by finding cracked solder joints on the microswitch that tells the microcontroller that the tray is open, and thus shuts the motor off. Reflowed the joints and added some fresh solder. So now it plays, but it intermittently skips after a minute or so. That tells me the laser is probably fine, and that the tracking is off. Fixed the tray, and will tackle the power supply capacitors that filter the power to the laser focus, tracking, spindle motor, and sled motor this evening. Hopefully that clears up the problem. Nice looking player, with decent sound quality (until it skips). Luxman dz-122.
Viva, here is that nak sr4a in action. I listen to it everyday for hours at a time. I love it.
Attachment 353357Attachment 353358Attachment 353359Attachment 353360
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Whelp, dove into another project instead tonight. Since my mouser order arrived... Great service by those guys by the way. Every time. Fast accurate, good. Anyway, I sold some guy a krell preamplifier, and he was trying to beat me up on price, which was annoying since I had brought it to him, (it was very close to the rc car store, again... He.) And finally he said, how about a busted amplifier for $50 off price, ok, since I'm a sucker for broken stuff, I said sure, what is it, a Linn lk85. Supposedly pretty well regarded chip amp. So being the sucker I am, I grabbed the box without even checking it out, and brought it home with me. Indeed it was busted. Both chips had basically blown up. So I ordered a couple new ones, took it apart, and the eparta arrived today. Put the new chips in, repaired a couple of burned traces, and put it back together. Fired it up with a dim bulb tester, and...Bam! It works. Removed the dim bulb tester and took some measurements. Dc offset nice and low around 3mv on each side. Clean sine wave coming out at a few different frequencies, and then tested with a speaker. All good.
See my new toy? Measuring the input signal in blue, and the output in yellow...
I am going to head back downstairs and hook it up to the basement system and see how she goes.
Check it out...
Linn LK85 chip amp.
Attachment 353499Attachment 353500Attachment 353501Attachment 353502Attachment 353503Attachment 353504
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Decent deal here... Not mine. But these are so good someone should grab it.
https://www.facebook.com/marketplace...9510009554784/
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If you don't have some already, some thermal tweezers are a godsend for surface mount stuff. There are always-hot ones for reflow and removal as well as quick-heat ones for installation.Quote:
Originally Posted by basinbeater
Gonna have to get some smt stuff. But not until I finish the next project. Just grabbed a apt holman preamplifier. Needs a lot of work, but is in excellent cosmetic shape. It's gonna get all new semiconductors, and capacitors, and a few key matching resistors. Attachment 354214
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Nothing ground breaking here, but small personal victory in getting my new vfd to output from my arduino! Fkna!
Attachment 355479
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Haha! Progress! Still waiting for a multiple input relay switching board to show up on the slow boat from china, and then I can program the arduino to switch inputs, and I will program the display to show whichever input was selected. Should be a single pushbutton affair. Pretty stoked I got the display to work. It's a little bright, but than can be adjusted in the arduino code pretty easily. I was scared of it, so it sat on the shelf for a month, but, it works! Yay, even the kids are pretty impressed. Wife, not so much, "when are you going to fix _______ ?"
The amp is a gb150d in case you couldn't tell, and it should be good for 150 watts per channel, but my transformer is a bit undersized, so this one is probably only good for 100, but have good headroom. It sounds very good, a little warmer than the honey badger it is sitting on top of. It is a mosfet diy amp developed by Greg ball. Attachment 355752Attachment 355753Attachment 355757
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Couple more construction pics.
Attachment 355761Attachment 355762
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One thing I love about arduinos is the abundance of sample/premade code out there. I'm an okay programmer (classes in html, visual basic, c++, matlab, etc years ago) but if I can spend half an hour searching for code similar to what I need, look at the syntax and figure out what's different than what I've used in the past, edit, and test instead of spending 10 hours making it all from scratch then I'll take that as "easy."
Yep. I'm waiting on the input board, but have already written code that will allow me to cycle through inputs with a single pushbutton. Most of it was copied from someone else's code. Arduino is kind of neat.
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My apt holman preamplifier that arrived just before Christmas got a fairly thorough going over. It arrived non functional. I repaired the power supply, replaced all electrolytic capacitors, replaced all opamps with a more modern model, cleaned all the pots, replaced the old relay with a more modern low signal relay on a perf board, and troubleshooted the mute circuit to figure out why it didn't work. Relay would buzz and not solidly engage. This last part was a chore because the mute circuit in my unit did not match the service manual schematic or the schematic on the bottom of the case. So I had to draw it out. After looking at it for a while, I decided to flip a couple parts around to go against their pcb markings, and now it works beautifully.
Great sounding unit. Top dog preamp in my house right now.
Attachment 356345Attachment 356346Attachment 356347Attachment 356348Attachment 356349
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I finally upgraded my main speakers and sub; I now have a Paradigm PDR 12 Sub I don’t need. It’s close to 20 years old, with the glued-on grill, so I can’t see the condition of the speaker. My new sub sounds much tighter, so I’m assuming the Paradigm is damaged or just plain worn out. Any point in trying to sell it? Anybody in OR want a speaker project?
I recently went home to say bye to a family member and while back I was telling my Dad about getting into old 2 channel stuff and he said he had some things I could have if i wanted. I turned down his Bose 901s, probably too heavy to ship and reviews on them just don't seem that positive. But I took him up on the Dynaco A25s. I dropped them off at UPS and they just showed up in Utah today.
https://live.staticflickr.com/65535/...93618b3c_b.jpg
I don't think they've been played in over 20 years. I've got them quietly playing on that old Sony, they sound really good. The high end on one of them doesn't sound quite right though, it's a little muffled. I've got new grill cloth coming and will be replacing the caps in them, hoping that clears up the muffled one, if not I'll find a replacement tweeter.
I've also upgraded the speakers in the living room system. I've got some Zu Dirty Weekends on order that should be here in a month or so but for now I found not 1 but 2 pairs of Polk Monitor 10Bs, each for $150. These sound really good, way better than they should for that price. Not the prettiest things to look at since they just have a vinyl wrap but the sound makes up for it.
https://live.staticflickr.com/65535/...82ff919b_b.jpg
And added a CD player to that system. The one pictured was just a cheapo Sony DVD player I had around but since then I scored a hell of a deal on a Sony DVP-S7700. Apparently this thing retailed for around a grand when new, I got it for $25. I've got a Schiit Modi 3+ DAC that is showing up today for it as well. Went to one of our local used music stores this past weekend and purchased a couple of CDs for the first time in a really, really long time.
Anyone in Utah need a cheap set of Polk Monitor 10Bs?
Sorry for your loss.
Pop open those dynacos and replace any capacitors in the crossover, the speakers should come to life. I was considering going to look at a set of those 10b. I'm tempted.
I love high quality vintage stuff.
I picked up a new to me, basically new condition Sony st-s333esg tuner. Best tuner I've ever had by far, better clearer reception, excellent bass, krcl never sounded so good.
The apt holman continues to blow me away with how much better it is than any preamp I've had to date. I've got the turntable hooked up to it now as well, and, well, I just can't stop playing music.
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New 30 year old tuner...Attachment 357595Attachment 357596
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I also have some stuff for sale, if a mag is interested, make you a deal.
Yamaha c6 preamp, could use a recap, otherwise, it works fine, some occasional scratchiness in the tone controls, but they work.
Sony ta-e1000esd preamp. I've recapped it with nichicon and elna caps, and it has opamp sockets and upgraded opamps installed. Works 100% except for the headphone out. I had to pull the muting transistor to use in one of the main speaker outputs, so I disconnected the head phone out.
Linn lk85 chip based power amplifier. Works great.
Phase linear 200 power amp. Faceplate rack bolts are genuine Porsche 928s4 valve cover bolts.
Works great.
Attachment 357597Attachment 357598Attachment 357599Attachment 357600
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These are brilliant fucking speakers for the price! I ordered mine last Oct. 1, minutes after they started accepting orders for the new production batch. I went with the tweeter cap upgrade and the rubber footsie-thingys. A great match for my Rogue Audio integrated. Very impressive base response, too.Quote:
Originally Posted by dfinn
Attachment 357642
That’s a rad little listening area you’ve got there! I also went with the Clarity cap upgrade. And I got the Walnut finish. Pretty excited to hear them.
I’m about to order caps for the Dynacos. They sound really good as is but they deserve some TLC.
My 10Bs are on KSL. Unlikely you’d find a nicer set. Unless you found a pair new in the box but that would be really hitting the lottery. 🤣
Mag price is a little better than what I have them listed at, happy to audition them if you want to have a listen.
@Viva, did you make that rack? I need something just like that.
No. That's an Salamander component rack that I picked up many years ago.
That's a nice lookin system.
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Ever get that feeling that you can build anything? Well, I got that feeling last night!
My arduino project finally came together and I now have a functional integrated amplifier that I built myself. I would like to thank the inventor of zip ties...
Amplifier is a gb150d designed by Greg ball, assembled into a rotel receiver case and transformer and heat sink. Power supply is arcam. Display is a futaba 2x20 vacuum fluorescent display, and input switching is handled by a small 4 relay board. The display and input switching is handled by an arduino nano and a single pushbutton is used to cycle through the inputs.
Here is a video of the unit in action! Wahoo!
https://youtu.be/ScIkjyl3aQA
Attachment 357997Attachment 357998Attachment 357999Attachment 358000Attachment 358001
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I want to see 'TK421'. That's what you need to display.
Man, and I thought I was a dork.
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Hey viva, you have a pair of ads l1230 isn't that right? How would you compare them to the Zu?
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You NEED all that bass.Quote:
Originally Posted by basinbeater