Hello there, I'm not sure if I mention anything about navigating the wires?, can't 'recall. Nonetheless, I'll make mention of something that may help. Make or buy some wire identifiers, i.e. wire labels and label the wires needing removal in whatever sequence that works for you. Usually if the posts on the board/s are marked 1,2,3,4 etc., then you want the wire labels to correspond with their designated post / termination. Then, if you have a wire wrapping / unwrapping tool/s you could neatly start unwrapping selected marked wires and "liberate" the board from them if you prefer or need to. I'm not going to address the specific use of wire wrapping tools, as I'm sure there are plenty of how to videos on that topic. So, as you can see, it's as straight-forward as labeling your wires to "MATCH" their termination points so you know where to return them. Another side note before I move to the finish line: You may need a few different sizes of wire wrap / unwrap tools based on the wire size of course, so, just something to keep in mind and no big deal otherwise. In fact, you technically don't need wire wrap tools. Sometimes I just carefully "untwirl" the wire from around the post to loosen and remove it. If you do it that way, just make sure the wires are long enough to provide some slack, so you can re-strip and re-twist a new connection point as needed. Sometimes you'll break the old coil of wire as you try to untwist it. Additionally you may need to heat up / de-solder some of the wire wrapped terminals that have been soldered upon during previous repairs etc. As far as getting the wires back on, just re-wrap them on the posts neatly. Again just find some information on using a wire tool (easy enough) and then re-secure good "bomb proof" connections of the wires and posts. A lot of times you can just re-twist the wire around any type of shaft, i.e. a small punch, or my spring hook that gradually tapers from smaller to larger, so I can "eye-ball" an inner diameter slightly bigger than the post diameter. Then you can just push the coil over the post and neatly solder the joint (fill in the gaps between the coils and post) and establish another secure connection. So, there's enough info to hopefully get you going / thinking about what technique/s you want to work with. Lastly, and in some cases, if you can get creative with circuit board positioning / securing, you can carefully gain access to needed components and work on boards without having to remove all the resident wiring. You just need to be aware and careful not twist the wiring around too many times and too aggressively. If wires start popping off and you don't know where they go, things will get a bit more time consuming, so, you may still opt to mark the wires, in case of a "pop loose event", or just be very careful / attentive when moving boards with attached wiring. Again, hope this helps, my best to you.
@@retroelectrotech Thank you for informing me. Must admit, did know about this tool. I will do the labels and take lots of pictures, and try to replace parts without the tool. If not working I will invest in the tool. Thanks again.
In past week I finished restoring my SX-1010 that had many problems created by the previous owner who attempted to recap and replace transistors and diodes. There were numerous boards with diodes and transistors installed incorrectly. If I had to guess what may be your issue, I’d say it’s a faulty transistor that was overheating and shutting off, but now that the output amplifier board is away from the large output transistor heat sinks it staying cooler.
Hello there, interesting theory, and certainly possible. However, it would appear that many times during testing, the right channel would "misbehave" even before the amp started really heating up / dissipating heat (very quickly in other words). Now with the board out it's holding steady as mentioned, even during the periods when I'm working the amp "hard and heavy" (making it sweat) 🙂. Nonetheless, those old (known problematic) transistors need to be pulled, the electrolytics need replacing etc. This unit needs a lot of work. We'll see if the customer will give me the "green light". Thank you for chiming is with your very logical input.
At 23:03 on the far right of the board looks like a fried resistor on the edge of the board. It's the veriticle resistor between the two rows of horizontal resistors.
Pardon the delay getting back to you, yes, I took care of that a while back, thank you so much though for having an observant eye and letting me know regardless :-)
My original capacitors were mostly within tolerance. When you measured very high ESR values, you could get that if your LCR meter is using too high a frequency, drop it down to 100 Hz
Yes, test frequency does change the reading, I was testing the other "cooked" power supply caps (on the SX-1280) at 120 Hz. They were absolutely Gonzo! 🙂
you know, i've got a computer at my bench and the monitor is right at my workspace and i do pull up service manuals and schematics but nothing beats blowing a schematic up poster size, sticking it on a bulletin board and getting out different colored highlighters! those fisher price soldering irons aren't all they are cracked up to be but sure seems like a lot of people bought them anyway.🙃
At 22:45 you can see a burned resistor on the right side of the board. I'm still saying a driver transistor is going intermittent emitter-base for your main problem.
Thanks for pointing out that resistor, I did swap it out a few days back. Out of curiosity at this point in this repair, I'm still monitoring the right channel and it remains "rock solid" ever since I removed the board, not a single hint of intermittent behavior. Prior to removing the board, the problem would appear shortly after power up, even before a real rise in temperature, and it remained fairly consistent. Now of course the problem has "gone dormant" 😀. I've hit the transistors with heat, freeze, spray, movement, board flex, spit, bubblegum, prayer, sweet talk, unkind words etc., and the right channel waveform has held steady since board removal, at least at this point. All the voltages on the board are looking good as well. So, at least at this point that's why the problem appears to (to some extent at least) be "connection related". Of course, due to the age of this unit and its component population, and the fact that there are some caps and transistors present that are on the "poop list", the amp boards (among other areas in this unit) need restoration level work as you know, which is the direction I advised the customer to go. So, we'll see what he wants / is able to spend. If the problem had remained present, or if it returns, I'll indeed zero in on it...To be continued 🙂
Yes, R17 belongs at the end of someone's roach clip, it's still giving us 440 ohms though, tough little resistor wants to keep living. But yes, this unit needs a lot of work, plenty of old problematic parts that need to go. Thanks for chiming in as always, and for pointing out the toasty resistor, I've been super tired / running and gunning non-stop, today I will rest up :-)
@@retroelectrotech i just took a couple of days to rest up myself. i've been going at it pretty good lately. gotta give ourselves a break now and then. enjoy the music for a change with the enhancer of choice. rock n roll🎸
Doing a 1010 now. I sure was hoping to see how you "unwrapped the wires", Part 4?
Hello there, I'm not sure if I mention anything about navigating the wires?, can't 'recall. Nonetheless, I'll make mention of something that may help. Make or buy some wire identifiers, i.e. wire labels and label the wires needing removal in whatever sequence that works for you. Usually if the posts on the board/s are marked 1,2,3,4 etc., then you want the wire labels to correspond with their designated post / termination. Then, if you have a wire wrapping / unwrapping tool/s you could neatly start unwrapping selected marked wires and "liberate" the board from them if you prefer or need to. I'm not going to address the specific use of wire wrapping tools, as I'm sure there are plenty of how to videos on that topic. So, as you can see, it's as straight-forward as labeling your wires to "MATCH" their termination points so you know where to return them. Another side note before I move to the finish line: You may need a few different sizes of wire wrap / unwrap tools based on the wire size of course, so, just something to keep in mind and no big deal otherwise. In fact, you technically don't need wire wrap tools. Sometimes I just carefully "untwirl" the wire from around the post to loosen and remove it. If you do it that way, just make sure the wires are long enough to provide some slack, so you can re-strip and re-twist a new connection point as needed. Sometimes you'll break the old coil of wire as you try to untwist it. Additionally you may need to heat up / de-solder some of the wire wrapped terminals that have been soldered upon during previous repairs etc. As far as getting the wires back on, just re-wrap them on the posts neatly. Again just find some information on using a wire tool (easy enough) and then re-secure good "bomb proof" connections of the wires and posts. A lot of times you can just re-twist the wire around any type of shaft, i.e. a small punch, or my spring hook that gradually tapers from smaller to larger, so I can "eye-ball" an inner diameter slightly bigger than the post diameter. Then you can just push the coil over the post and neatly solder the joint (fill in the gaps between the coils and post) and establish another secure connection. So, there's enough info to hopefully get you going / thinking about what technique/s you want to work with. Lastly, and in some cases, if you can get creative with circuit board positioning / securing, you can carefully gain access to needed components and work on boards without having to remove all the resident wiring. You just need to be aware and careful not twist the wiring around too many times and too aggressively. If wires start popping off and you don't know where they go, things will get a bit more time consuming, so, you may still opt to mark the wires, in case of a "pop loose event", or just be very careful / attentive when moving boards with attached wiring. Again, hope this helps, my best to you.
@@retroelectrotech Thank you for informing me. Must admit, did know about this tool. I will do the labels and take lots of pictures, and try to replace parts without the tool. If not working I will invest in the tool. Thanks
again.
In past week I finished restoring my SX-1010 that had many problems created by the previous owner who attempted to recap and replace transistors and diodes. There were numerous boards with diodes and transistors installed incorrectly.
If I had to guess what may be your issue, I’d say it’s a faulty transistor that was overheating and shutting off, but now that the output amplifier board is away from the large output transistor heat sinks it staying cooler.
Hello there, interesting theory, and certainly possible. However, it would appear that many times during testing, the right channel would "misbehave" even before the amp started really heating up / dissipating heat (very quickly in other words). Now with the board out it's holding steady as mentioned, even during the periods when I'm working the amp "hard and heavy" (making it sweat) 🙂. Nonetheless, those old (known problematic) transistors need to be pulled, the electrolytics need replacing etc. This unit needs a lot of work. We'll see if the customer will give me the "green light". Thank you for chiming is with your very logical input.
At 23:03 on the far right of the board looks like a fried resistor on the edge of the board. It's the veriticle resistor between the two rows of horizontal resistors.
Pardon the delay getting back to you, yes, I took care of that a while back, thank you so much though for having an observant eye and letting me know regardless :-)
My original capacitors were mostly within tolerance. When you measured very high ESR values, you could get that if your LCR meter is using too high a frequency, drop it down to 100 Hz
Yes, test frequency does change the reading, I was testing the other "cooked" power supply caps (on the SX-1280) at 120 Hz. They were absolutely Gonzo! 🙂
you know, i've got a computer at my bench and the monitor is right at my workspace and i do pull up service manuals and schematics but nothing beats blowing a schematic up poster size, sticking it on a bulletin board and getting out different colored highlighters! those fisher price soldering irons aren't all they are cracked up to be but sure seems like a lot of people bought them anyway.🙃
Yes indeed, having a hard copy of a schematic is preferred for sure, and you're right, the Fisher Price soldering iron was a best seller ;-)
At 22:45 you can see a burned resistor on the right side of the board. I'm still saying a driver transistor is going intermittent emitter-base for your main problem.
Thanks for pointing out that resistor, I did swap it out a few days back. Out of curiosity at this point in this repair, I'm still monitoring the right channel and it remains "rock solid" ever since I removed the board, not a single hint of intermittent behavior. Prior to removing the board, the problem would appear shortly after power up, even before a real rise in temperature, and it remained fairly consistent. Now of course the problem has "gone dormant" 😀. I've hit the transistors with heat, freeze, spray, movement, board flex, spit, bubblegum, prayer, sweet talk, unkind words etc., and the right channel waveform has held steady since board removal, at least at this point. All the voltages on the board are looking good as well. So, at least at this point that's why the problem appears to (to some extent at least) be "connection related". Of course, due to the age of this unit and its component population, and the fact that there are some caps and transistors present that are on the "poop list", the amp boards (among other areas in this unit) need restoration level work as you know, which is the direction I advised the customer to go. So, we'll see what he wants / is able to spend. If the problem had remained present, or if it returns, I'll indeed zero in on it...To be continued 🙂
21:31 looks like R17 let the magic smoke out. q5,6 are probably on their way out.
Yes, R17 belongs at the end of someone's roach clip, it's still giving us 440 ohms though, tough little resistor wants to keep living. But yes, this unit needs a lot of work, plenty of old problematic parts that need to go. Thanks for chiming in as always, and for pointing out the toasty resistor, I've been super tired / running and gunning non-stop, today I will rest up :-)
@@retroelectrotech i just took a couple of days to rest up myself. i've been going at it pretty good lately. gotta give ourselves a break now and then. enjoy the music for a change with the enhancer of choice. rock n roll🎸
@@josephlalock8378 Amen to that brotha,!