With the limited amounted of space I have to work on stuff -- I literally have to make room to do this. Don't worry -- it will be unvieled soon.Lasonic TRC-920 said:
The case for avoiding molested boomboxes.
- Thread starter Superduper
- Start date
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Not the unvieling of my boombox that I was speaking of.
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But this week, I worked on a boombox for another member. The deck was dead. It needed belts, that was for sure. So after rebelting, lubing, etc but before reassembling it, I tested the deck with a 9v battery to confirm that all functions work properly. I frequently do this with servo assist decks since it's hard to tell if the transport works properly without motor power. Of course I also wanted to confirm that motor was not fried. Anyhow, all seemed to work OK. But I knew it would require some work on microswitches since those were all mangled. Someone worked on it before and hooked the switches on the web of wires deforming them. Also, there were missing screws everywhere. A couple of screws were actually installed crooked/cocked.
So replaced the microswitches from a donor deck, put it back together and no power. Dead as a doornail.
Checked power at the controller board leads that powers the motor -- nada. This is a fairly complicated deck controller with it's own board. Yet, I knew that the motor was good. Anyhow, after my gut feeling tells me that maybe this boombox was MOLESTED more than I initially thought, I put both decks (subject and donor) together side/side and what did I see? A handful of individual pigtail wires -- all connected to WRONG SPOTS! Shiat Dammn to Heck! Anyhow, suspecting that the controller was fried since that board actually has lots of components, I swapped them. After some time of tedious soldering/desoldering, the boards were swapped and no joy.
The bottom line.... figured out that the mis-installed pigtails, some of which went to the power supply knocked out that section of the power supply. :annoyed: That's why the deck never worked. The PS is a complicated unit with multiple regulated branch circuits. I count at least 3 regulators on board. I suspect that separate power branches powers the amp, tuner, deck, etc. Anyhow the portion that powers the deck was dead and after properly reconnecting everything and replacing the PS, it works well now.
If I did not have at my disposal, a donor to compare to (or service documentation), I would've never been able to discover the miswired deck controller since there was nothing intuitive about where each pigtails go. These aren't like 3 or 4 ganged connectors. These are single wires that goes to a single unmarked peg.
So chalk up another case, in support of avoiding molested boomboxes. Unfortunately, this scenario seems to replay itself over and over again like a broken record. I am convinced that many people just don't know what they are doing and simply shouldn't be allowed near the innards of a boombox. I sure wish there was such thing as a registered boombox offender/molester list.
:grim: That knucklehead caused serious damage to the machine with just a handful of shuffled wires. I am convinced that in an effort to fix the deck, this guy haphazardly disconnected all the wires without taking notes or documenting where the cables went (didn't need to disconnect those wires in order to rebelt the deck) and didn't know where they went and simply find a hole, and plugged it, over and over again until all holes were plugged. Didn't even bother to put all the screws back. What a dork...... 
But no, the member who asked me to do this did not do this. All of this "work" was done by the previous owner.
============================================
But this week, I worked on a boombox for another member. The deck was dead. It needed belts, that was for sure. So after rebelting, lubing, etc but before reassembling it, I tested the deck with a 9v battery to confirm that all functions work properly. I frequently do this with servo assist decks since it's hard to tell if the transport works properly without motor power. Of course I also wanted to confirm that motor was not fried. Anyhow, all seemed to work OK. But I knew it would require some work on microswitches since those were all mangled. Someone worked on it before and hooked the switches on the web of wires deforming them. Also, there were missing screws everywhere. A couple of screws were actually installed crooked/cocked.
So replaced the microswitches from a donor deck, put it back together and no power. Dead as a doornail.
Checked power at the controller board leads that powers the motor -- nada. This is a fairly complicated deck controller with it's own board. Yet, I knew that the motor was good. Anyhow, after my gut feeling tells me that maybe this boombox was MOLESTED more than I initially thought, I put both decks (subject and donor) together side/side and what did I see? A handful of individual pigtail wires -- all connected to WRONG SPOTS! Shiat Dammn to Heck! Anyhow, suspecting that the controller was fried since that board actually has lots of components, I swapped them. After some time of tedious soldering/desoldering, the boards were swapped and no joy. The bottom line.... figured out that the mis-installed pigtails, some of which went to the power supply knocked out that section of the power supply. :annoyed: That's why the deck never worked. The PS is a complicated unit with multiple regulated branch circuits. I count at least 3 regulators on board. I suspect that separate power branches powers the amp, tuner, deck, etc. Anyhow the portion that powers the deck was dead and after properly reconnecting everything and replacing the PS, it works well now.
If I did not have at my disposal, a donor to compare to (or service documentation), I would've never been able to discover the miswired deck controller since there was nothing intuitive about where each pigtails go. These aren't like 3 or 4 ganged connectors. These are single wires that goes to a single unmarked peg.So chalk up another case, in support of avoiding molested boomboxes. Unfortunately, this scenario seems to replay itself over and over again like a broken record. I am convinced that many people just don't know what they are doing and simply shouldn't be allowed near the innards of a boombox. I sure wish there was such thing as a registered boombox offender/molester list.
:grim: That knucklehead caused serious damage to the machine with just a handful of shuffled wires. I am convinced that in an effort to fix the deck, this guy haphazardly disconnected all the wires without taking notes or documenting where the cables went (didn't need to disconnect those wires in order to rebelt the deck) and didn't know where they went and simply find a hole, and plugged it, over and over again until all holes were plugged. Didn't even bother to put all the screws back. What a dork...... But no, the member who asked me to do this did not do this. All of this "work" was done by the previous owner.
So what box were you working on SD??Superduper said:Not the unvieling of my boombox that I was speaking of.
============================================
But this week, I worked on a boombox for another member. The deck was dead. It needed belts, that was for sure. So after rebelting, lubing, etc but before reassembling it, I tested the deck with a 9v battery to confirm that all functions work properly. I frequently do this with servo assist decks since it's hard to tell if the transport works properly without motor power. Of course I also wanted to confirm that motor was not fried. Anyhow, all seemed to work OK. But I knew it would require some work on microswitches since those were all mangled. Someone worked on it before and hooked the switches on the web of wires deforming them. Also, there were missing screws everywhere. A couple of screws were actually installed crooked/cocked.
So replaced the microswitches from a donor deck, put it back together and no power. Dead as a doornail.
The bottom line.... figured out that the mis-installed pigtails, some of which went to the power supply knocked out that section of the power supply. :annoyed: That's why the deck never worked. The PS is a complicated unit with multiple regulated branch circuits. I count at least 3 regulators on board. I suspect that separate power branches powers the amp, tuner, deck, etc. Anyhow the portion that powers the deck was dead and after properly reconnecting everything and replacing the PS, it works well now.
So chalk up another case, in support of avoiding molested boomboxes. Unfortunately, this scenario seems to replay itself over and over again like a broken record. I am convinced that many people just don't know what they are doing and simply shouldn't be allowed near the innards of a boombox. I sure wish there was such thing as a registered boombox offender/molester list.
It's not important and since it's not my box but belongs to another member, I will be discreet since it's not really my call to disclose it. The purpose is just to share with you guy the things that I see all the time in the ongoing soap opera.... "The adventures of boombox repairs".
I was quite happy with my M70 when I first got it. I then noticed that the right volume slider was dead and both speakers were controlled by the left. Opened it up to find the right amp dead and the left channel split to drive both speakers. All they had to do was swap out a chip (I think it was a chip or hybrid/pack style output, can't remember). Luckily I've never had any of the messes you're describing.
Superduper said:I am convinced that many people just don't know what they are doing and simply shouldn't be allowed near the innards of a boombox. I sure wish there was such thing as a registered boombox offender/molester list.
So..........
As some of you know, I have a Sanyo M9994 that I was offering for sale. Some of you may have noticed I mentioned a non-swinging left meter. Another member has offered me a trade and we hammered out a deal. But I hate to send a boombox out like that, especially since it's going to another member. I was trying to NOT work on the boombox -- rather just sell it as-is. I have far too many that I want to do stuff to before offering them but time restraints and the fact that I never get to mine suggests that it may be better to just forget fixing everything.
Anyhow, I'm getting ready to ship it, but just how I am..... I just couldn't resist to take a peek at the meter situation. So after tracing the left meter circuit, I came to and found the problem.
SEE IT?
No? Ok, how about this:
Still no?
Ok, this is what I expected to find: These are a couple of other holes just "begging" to be filled and "screwed." Yep, there are trimpots under those solder pads and what looked like a mount hole was not. Instead, the screw managed to screw up the VR and bridge all 3-solder pads at once.
Those holes are there so you can make electrical adjustments from the backside.
Here is the broken and removed trimpot. Replacing it with a new one restored the meter operation.
AND SO....... Another case for avoiding molested boomboxes, and another example of things that shadetree technicians do in the course of fixing stuff. :grim:
As some of you know, I have a Sanyo M9994 that I was offering for sale. Some of you may have noticed I mentioned a non-swinging left meter. Another member has offered me a trade and we hammered out a deal. But I hate to send a boombox out like that, especially since it's going to another member. I was trying to NOT work on the boombox -- rather just sell it as-is. I have far too many that I want to do stuff to before offering them but time restraints and the fact that I never get to mine suggests that it may be better to just forget fixing everything.
Anyhow, I'm getting ready to ship it, but just how I am..... I just couldn't resist to take a peek at the meter situation. So after tracing the left meter circuit, I came to and found the problem.
SEE IT?
No? Ok, how about this:
Still no?
Ok, this is what I expected to find: These are a couple of other holes just "begging" to be filled and "screwed." Yep, there are trimpots under those solder pads and what looked like a mount hole was not. Instead, the screw managed to screw up the VR and bridge all 3-solder pads at once.
Those holes are there so you can make electrical adjustments from the backside.
Here is the broken and removed trimpot. Replacing it with a new one restored the meter operation.
AND SO....... Another case for avoiding molested boomboxes, and another example of
things that shadetree technicians do in the course of fixing stuff. :grim:
Hi Guys, Thought I would use this thread for my first post on this forum!
I used to work for a Sharp agency back in the 80's and worked on a lot of this gear when it was new.
Just a quick tip if you ever find yourself with a couple of similar connecting plugs wondering which one goes where...
Look at the body of the plug and you will usually find half a felt pen line / mark on it.....the other half is on the socket....put the pug into the socket and see if the marks align. If they match up then thats where it lives!
It was quite a common way of marking connectors up when there were lots of similar sized connectors.
Hope this helps!
I used to work for a Sharp agency back in the 80's and worked on a lot of this gear when it was new.
Just a quick tip if you ever find yourself with a couple of similar connecting plugs wondering which one goes where...
Look at the body of the plug and you will usually find half a felt pen line / mark on it.....the other half is on the socket....put the pug into the socket and see if the marks align. If they match up then thats where it lives!
It was quite a common way of marking connectors up when there were lots of similar sized connectors.
Hope this helps!
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