MiKro
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Everything posted by MiKro
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@Bizman62 HAHA!! No smoke so far. All is good. Going through the slow steps of startup as if I built this from scratch. MK .
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Oh so close. I had an LED that was a problem. I had to rewire the p/p pot to fix that. Other than that, all is looking good so far. Tomorrow will be try it with tubes and make adjustments. Hopefully soon it will be right. Fingers crossed. MK
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So the secondary wires are in as well as the heater wires, A few ground wires and the standby switch. I moved the the Standby switch and small ground wires to the back side of board. Relocated the heater wires to allow me to get some distance in height above the secondaries to help on hum. Hopefully that will help? A few more wires to do, Check solder joints again and re-flow any that need it. Then to finish cleaning and recheck everything again. Then it's time to do the slow process of startup and test. MK Here you can see where it was update to the 93 upgrades
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Well it is now back in the chassis for the final test fit. I can now remove, it clean it, then go back together,. LOL mk
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So testing the fit, one more p/p-pot to do then I can go back together with this thing. Got to clean it up first It's not pretty as the originals but will function fine and get the job done. LOL MK
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Since I cannot get PCB type push/pull 250K linear pots anywhere anytime soon I went with lugged p/p pots. what a bitch to add. So I had to add wires and make it all somewhat flexible so they will fit in the chassis. Here is one done. My soldering looks like hell. hard to do while floating in air. LOL Damn I need to get to my real workbench. I will clean them up once mounted so they are in place and not moving. LOL MK
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Dang it I found 2 more electrolytic caps on the EQ board hiding under the cables. LOL Have to fix those as well.. They are going to be a bitch to get to as the slider bodies are in the way. MK OLD New
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I agree, just giving you options. Looks like a cool project. I like that you are using aluminum extrusions and plate. much beefier. You can always make a small circuit using a start cap that should give you that soft start to control the inrush current. MK
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Yes using a VFD for AC or similar type of ESC which you could use for DC if a brushless DC 3 phase motor, AC will keep the torque a constant as well but within limits. again expense here AC vs DC. If using DC brushed motor, Using a type of DC Variac with PWM will keep the torque constant as well and much cheaper. Something like a router control will not work as it only lowers voltage and the torque deceases as the voltage decreases in an AC system which I am sure you are aware of. mk
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Are you thinking DC or AC brushless? Either would work. Advantages of each need to be considered though? The DC would give you more torque at a fixed speed for less $$$, Whereas the AC would give you 3 phase with adjustable speed and torque. Cost is always a factor though as the AC would be more expensive. Just my 0.02 cents. MK
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I got the wires in place for the push pull pots. All color coded so I can use lugged P/P pots, what a PITA. Need to clean up the joints some but I am much happier now. mk And for Carl, You can see the silicone on the caps now. I also replaced the 350 ohm 10 watt resistor as the other had cracks.
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I bought a new de-soldering tool the other day. Expensive Hakko one. It is now going back, as it started to sound like a Jet engine revving up after about 20 mins of use. Man I hate it when things fail. MK
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LOL, Yep It will be replaced. I am searching for a hum source while I am in this. I am beginning to think it may be the heater wiring. Or actually the lack of where they used traces instead. There was always a Hum in this amp back when I owned it? I always thought it was my home and its old wiring. Now with a better understanding of these things I am beginning to suspect differently. Al of the AC wiring to the tubes are just bundled together. they need to be in twisted pairs to help with shielding hum. Man o man what a nightmare as I really look at everything as a whole. I have also found what appears to be an added wire the tech did that looks to be a ground loop. F'me Maybe I just need to start over on this, toss the PCB and do a hand wired version of it.. LOL Just kidding as that would be a real PITA. mk
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SoI had a tech back in the mid 90s look at this. I suspect he was the flux culprit in to this thing and renewed the necessary parts. I am finding that his cleaning skills of flux sucked. One more thing I have to do. First though my power resistors look okay , no cracks in them but what appears to be Soldering iron burn marks? Again the old tech? Now the 10 watt resistor though has 3 cracks in it. So I think I will replace that one. LOL!! MK
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At this point I just want to be done with it. LOL. They are working fine So I plan to move forward. I agree there are better but I am not going to go that way currently. Thanks for the suggestions Carl. MK
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I didn't even look at those to be honest. LOL. All I want to do is fix the snap crackle pop. LOL. The pots were very suspect as was also the electrolytics. I know the Power tubes are very old so they need replacing, so I decided to change them all out including new preamp tubes. This should bring this amp up too almost new. Will see what it sounds like when I am done? The trannies test out okay. The only thing left to do if still any problems will be to look at the polyfilm caps and transistors. Hopefully they are not an issue. Looking at the schematics they say that All of the Op-Amps are 4558 TYPE. MK
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They are not fun. This one actually has decent traces and pads. mk
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So today I pulled all of the pots off the board. What a PITA that was. the push/pulls had 9 connections. F"me. LOL Waiting on so new ones that are not PCB mount so I will wire them to the board. Ones that were PCB would be next year before I could get them. I will have to add 2 stand offs on the board in the front to hold it in place. No big deal as it already has holes for that as does the chassis. MK
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You are too funny. ::)
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No machine is plug and play. They all require some effort and learning. I have people that buy my 3d guitar models on Etsy and I specifically state they are not for beginners. They still buy them even though they just got there machine and totally new to CNC. Then they bitch because they cannot put the model in the software and press a button to make it. Then they demand their money back? MK
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I agree Andrew. Still if it might help, it is worth the extra few minutes to align it properly. MK
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Already on the things to do. I could not find my tube of silicone so I have to buy another. LOL MK
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They are still caps and being such they are built with an outer foil/shield just like most caps are. It is not as defined ( lack of better words) but it is still there. If you test caps with an oscillascope you will find they all have a negative and a positive side to them based on EMI influence. that being said the foil/shield/ neg side should go to ground of circuit flow. Even Orange drops and other types this is common. Also if you rely on the marking of a cap for negative you may be wrong as many test show that they just go thru a machine and the band is applied with no real reference to the actual construction of the cap. Here is a great video that explains it more. Caps in backwards? Video mk
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All of the electrolytic caps are now replaced. Adjustable bias part I made is wired in place. Pots are cleaned. Now to reinstall this and check /set the bias with the new tubes. Oh boy such fun. LOL!!! MK update: I finally found some pots that I can use. They are not for PCB but I can wire direct to the board so that will fix any problems as far as the pots go. I will need to add 2 additional standoffs to support the board since the pots were the front support in the chassis face. I would rather do this now than have to pull it out later to change them as I know some are on the verge of being very questionable as far as working properly. I have used deoxit over the years and it was becoming less and less effective. LOL
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So the 10uf 50v NP/BP caps came in today. Even though they are Non-Polarized/Bipolar, I need to put them on the scope to find the cathode so I can put the shielded side of the cap going the correct direction for the best audio. MK
