Monkeyboi Posted January 13, 2023 Posted January 13, 2023 (edited) Just got a DIY built amplifier on the bench getting repaired whilst I await the delivery of parts / materials for other repairs. I don't know the origins of this DIY amplifier (IOW who built it) but unfortunately it's an electric shock / electrocution hazard just waiting to happen. Other than it's a complete dog's breakfast the metal casing is NOT EARTHED to the mains protective earth and furthermore there isn't any evidence to suggest it ever was. The power socket is a standard IEC three pin job with an integral M205 fuse holder. The earth spade terminal shows no signs of ever having a connector attached to it. In addition the correct way to provide a protective earth connection to this lug is to solder a wire to it and secure the other end to the conductive chassis with a fully closed eyelet connector and a shake proof washer. This is the minimum electrical safety requirement for non-double insulated mains powered appliances in Australia. The hole that was drilled to accommodate the power switch is oversized and the switch could literally be pushed out of the panel with very minimal pressure. Also, whomever wired this up had no idea that if you are using only a single pole switch you MUST switch the ACTIVE (live) side not the NEUTRAL !!!! The fitted fuse was twice the recommended current rating for the amplifier. Given there is no additional over current protection within the amplifier this is a serious oversight. Another electrical hazard was just twisting mains wiring up and wrapping it in insulation tape which was unravelling. The chassis has two large holes cut into the back panel. These are large enough to get several adult sized fingers through. One can easily touch the long uninsulated leads of the NTC thermistor on the mains side of the transformer. This is another potential electric shock / electrocution hazard. Please guys, if you are DIYing and don't know the Australian electrical safety standards for use of appliances in Australia and New Zealand I respectfully suggest you read up on them or at minimum pass your project over for inspection to someone that does. This is no laughing matter. If the active wire of the mains somehow made contact with the metal chassis it might have resulted in a fatality. I urge the less experienced DIYers that are building mains powered equipment to visit the "Does it Comply " thread pinned at the top of this sub-forum. If not for you own safety but also that of others which might very well be your loved ones. Edited January 13, 2023 by Monkeyboi added linked URL 9 1 2
acg Posted January 13, 2023 Posted January 13, 2023 @Monkeyboiyes, very important information. A lot of "stuff" (i.e. standard and safe electrical wiring and procedure) is not covered in diy kits as it is often considered routine by those that regularly do it. Even things like grid stoppers in valve amps are sometimes left off schematics because it is just routine that you'll need one and should be able to calculate its value. Plenty of other examples too where it is easy for the less experienced to go wrong. All of my diy builds are multi panel and shelf and before power is applied for the first time I measure the resistance to PE of them all to be more sure of safety. 1
BRS Posted January 13, 2023 Posted January 13, 2023 And that ls why I don't plan on dabbling in this area. Passive speakers is as far as I am prepared to go. 2
Addicted to music Posted January 13, 2023 Posted January 13, 2023 It’s not just DIY either. I’m sure if you lift the top cover of some audio components that’s straight of the ensemble line also have the issue and there are many reports in every audio forum complaining about “hum” and when there is a mention of this you can bet bottom dollar that something like this has been missed. I’ve seen white goods manufacturers, a 3M professional vacuum cleaner that’s made in the US, where the IEC female comes out in your hand when you try to unplugged the cord, power switches that have the wrong size hole punched and the switch gets pushed into the product are not new, It’s either bad manufacturing and lack of QC that can be serious safety issue. There was an SNA member here, that’s BS on all audio forums and when someone send one of his products in to ASR for testing, there was a break out where the item was taken apart, all I can say is what a scam! A recommendation is to stick with products that has a C tick and FCC certification as these would have passed certain standards to get onto the world stage, but even with this implementations you really need to establish whether the mains earth is connected to the metal chassis, you need to check every panel and some fail to scratch the paint off to achieve continuity. Here’s an example: https://www.audiosciencereview.com/forum/index.php?threads/schiit-saga-grounding-and-hum-issues.4737/ 3
Monkeyboi Posted January 13, 2023 Author Posted January 13, 2023 7 minutes ago, Addicted to music said: It’s not just DIY either. I’m sure if you lift the top cover of some audio components that’s straight of the ensemble line also have the issue and there are many reports in every audio forum complaining about “hum” and when there is a mention of this you can bet bottom dollar that something like this has been missed. I’ve seen white goods manufacturers, a 3M professional vacuum cleaner that’s made in the US, where the IEC female comes out in your hand when you try to unplugged the cord, power switches that have the wrong size hole punched and the switch gets pushed into the product are not new, It’s either bad manufacturing and lack of QC that can be serious safety issue. There was an SNA member here, that’s BS on all audio forums and when someone send one of his products in to ASR for testing, there was a break out where the item was taken apart, all I can say is what a scam! A recommendation is to stick with products that has a C tick and FCC certification as these would have passed certain standards to get onto the world stage, but even with this implementations you really need to establish whether the mains earth is connected to the metal chassis, you need to check every panel and some fail to scratch the paint off to achieve continuity. Here’s an example: https://www.audiosciencereview.com/forum/index.php?threads/schiit-saga-grounding-and-hum-issues.4737/ Thanks for sharing this. I would have expected better from Schiit Singularly disappointing to say the least, especially making the customer bear the cost of returning the unit to the factory for inspection on what is a safety related issue.
tesla13BMW Posted January 13, 2023 Posted January 13, 2023 Can't quite follow how to connect the earth..... wont bother as there is no hum Just joking - will go in an enclosure once I build the phono stage that will be in with it. 2
Monkeyboi Posted January 14, 2023 Author Posted January 14, 2023 After discovering a lot of dodgy spade connectors that hadn't been crimped correctly I decided to investigate further. Yes they were all loosey goosey, crimped with the wrong size connector for the gauge of wire and definitely with the wrong tool. And another thing. If you are going to use crimp connectors don't solder the strands of wire together. Crimp connectors will fail if the wire is soldered then crimped. Just to clarify any possible misconceptions, it's okay to crimp naked copper or tinned copper wire and then solder to exclude any air or moisture if this is approved by the manufacturer of the connector. Some should never be soldered under any conditions as the solder can flow back under the insulation of the wire which may lead to the stranded conductors fracturing if flexed. On removing the toroidal transformer from the chassis I discovered that it had been overtightened. So much so it had pancaked both rubber discs to such an extent that the windings of the transformer had literally cut through them. To add to the shoddiness of the build the rubber disc on the chassis side was peppered with aluminium swarf from the drilling of the chassis which was cutting through the discs and penetrating the insulation wrap around the windings. You can see this as the silvery white speckles in the attached photo. Whomever built this amplifier either didn't have a clue what they were doing or didn't give a damn. Possibly both? From inspecting this amplifier it's clear that the person who built it didn't even de-burr the holes in the metalwork or even wipe off the metal swarf. It looks slapped together by someone who was probably just interested in making a fast buck with little or no concern for the electrical safety or the quality of the build. Given that the metal chassis was not connected to the protective mains earth this might have been yet another avenue for electrical leakage to the unearthed metal casing. IMHO this sort of shoddiness is completely unacceptable, especially if it was built for use by another person or on sold for profit. If by slim chance you are reading this post and this is your handiwork I respectfully suggest you reconsider if DIY involving equipment wired to the mains electrical supply is really something you want to risk again. Given the list of electrical standards violations identified in just this amplifier alone let's just hope there aren't any other shoddy builds like this out there in the audio community. 4 1
Addicted to music Posted January 14, 2023 Posted January 14, 2023 (edited) Overtightened bolts on a toroidal Transformer where the rubber washer is compromised to the point it damages the winding, metal burrs still present and crimping female spade connections onto the single strand of a transformer winding saids to me whoever built it had no idea. You have to give it to them for having a go and no damage or electrocution has occurred. At least to components of the pcb are physically secured! I’ve seen products here that get sold where components/capacitors that are huge get soldered and are just sitting there, floating in a sea of spaghetti of wire waiting to be physically moved so it can short other open connections and you probably know whom I’m taking about! This person sells preamps with one of the worst workmanship I’ve have ever seen, if you want to go that path do it to yourself and not sell it to others! Spade connectors opens a can of worms. If you find spade connector in any product that don’t have a contact spring on the inside of the female, do not buy that product. Spade connectors are the worst connectors for ANY connections especially for mains power. All manufacturers that I deal with have moved on to screw on types or used high quality Molex that has a spring type connection so it’s a positive connection for the life of that product. They started doing this back in the early 90s. Typical audio manufactures and that includes ME uses spade connectors and not the 2.0 version that consist of a leaf spring that ensures positive connection. Spade connectors are easy way to connect wiring, however what happens over time is the female side connection goes loose and widens therefore the connectors are no longer physically connected, this damages the connection if high current is experienced and therefore over heats and in some mains applications catch fire; it’s the 1st time I saw purple plasma jumping across a damaged overheated connectors in a 35A 3 phase application that had original spade connections. The wiring and associated pcb has to be replaced! Even to this day audio manufacturers haven’t caught up! They are still used for speakers and also internals for amplifiers, even I’ve experienced in my build where a relay for speaker protection only comes with a spade, after 20yrs of use one of the channels started to drop in volume compared to the other, this is the effects of spade connectors of what over time does, the female metal side just physically widens naturally becoming poor electrical connections, that’s why the latest have a separate spring in the centre, so if it goes lose, it’s a non issue as the spring will still provide a positive contact, if you don’t have this, go to another connection or don’t even consider the product. If you look at all the current of Silicon Chips Amplifiers, they have moved onto High quality Molex that are screw on type, even for the audio signal. Edited January 14, 2023 by Addicted to music 1
Monkeyboi Posted January 15, 2023 Author Posted January 15, 2023 3 hours ago, Addicted to music said: Overtightened bolts on a toroidal Transformer where the rubber washer is compromised to the point it damages the winding, metal burrs still present and crimping female spade connections onto the single strand of a transformer winding saids to me whoever built it had no idea. You have to give it to them for having a go and no damage or electrocution has occurred. Well, not yet it hasn't, but given time IMHO it would have got a lot worse. Put it this way, it isn't going to be leaving here until it is fully electrically safe and compliant to AS/NZ standards. Unfortunately it is equipped with an IEC mains connector so simply cutting the mains cable off it isn't going to be a deterrent to someone simply plugging it into the wall outlet and powering it up. 4 hours ago, Addicted to music said: At least to components of the pcb are physically secured! I’ve seen products here that get sold where components/capacitors that are huge get soldered and are just sitting there, floating in a sea of spaghetti of wire waiting to be physically moved so it can short other open connections and you probably know whom I’m taking about! This person sells preamps with one of the worst workmanship I’ve have ever seen, if you want to go that path do it to yourself and not sell it to others! Whomever assembled the PCBs in this amplifier had no idea how to solder. I've attached some pics for your viewing pleasure. Beats me how it ever worked to begin with. Just for clarity I have taken these photos prior to me doing any fault finding or rework on the amplifier PCBs. There is some evidence that someone has already had a go at repairing these boards in the past. You can see fresher resoldering work albeit shiny balls of solder just sitting on the pads. Little silver apples. How they missed the obvious dry and fractured joints in beyond me. BTW, I know it's not generally considered good form to name and shame on SNA but feel free to PM me the name of the person who creates those preamps that you are referring to so I can actively avoid them in the future. In hindsight I now wish after taking a good look at this on the workbench that I should have just put the top cover back on it and declined the repair. Yes, that would have been the easy path but knowing how unsafe it is I couldn't in all honesty return it knowing the owner might very well attempt his own repairs and in doing so might have received a serious electric shock or even (heaven forbid) get electrocuted in the process. 3 hours ago, Addicted to music said: Spade connectors opens a can of worms. If you find spade connector in any product that don’t have a contact spring on the inside of the female, do not buy that product. Spade connectors are the worst connectors for ANY connections especially for mains power. All manufacturers that I deal with have moved on to screw on types or used high quality Molex that has a spring type connection so it’s a positive connection for the life of that product. They started doing this back in the early 90s. Agree on the "can of worms" comment. Most of the issues involving spade, eyelet and fork connectors is the failure on the part of the person fitting them to understand that the colour coding is relevant to the size of the conductors to be crimped and using the proper crimping tool. Way too many amateurs will probably purchase one of those "automotive crimp kits" on Ebay with an assortment of connectors and use those awful and practically useless el-cheapo crimping tools that comes in the box. All that "tool" does is damage the crimped section and the insulation surrounding it. Then they wonder why they don't work or fail shortly thereafter. 3 hours ago, Addicted to music said: Typical audio manufactures and that includes ME uses spade connectors and not the 2.0 version that consist of a leaf spring that ensures positive connection. I own two ME Sound products. An ME850HC power amplifier and an ME25 pre-amplifier. No spade connectors in either. In the ME850s Peter uses screw down terminations for all power related circuitry on Dinkle style PCB mounted connectors IIRC. I've also repaired a few ME850 power amps and haven't spotted any in them either. Those failures have mostly been with the ME branded electrolytic capacitors and one had a faulty logic gate IC on the power supervision PCB. I'm not sure if Peter used spade connectors in the past on other models but it's entirely possible he might have. My only negative critique of any connectors in ME gear is the audio ones. When my new ME850HC was deliver it was dead on one channel. The courier had given the crate it was shipped in somewhat of a hiding on its journey from FNQ to WA. One of the three pin connectors going from an input XLR to the PCB of the respective channel had come adrift in transit. Peter could have used a locking connector to overcome this from happening this but for some reason he didn't. I have subsequently retrofitted different connectors to both power amplifier PCBs so this won't happen again. 3 hours ago, Addicted to music said: Even to this day audio manufacturers haven’t caught up! They are still used for speakers and also internals for amplifiers, even I’ve experienced in my build where a relay for speaker protection only comes with a spade, after 20yrs of use one of the channels started to drop in volume compared to the other, this is the effects of spade connectors of what over time does, the female metal side just physically widens naturally becoming poor electrical connections, that’s why the latest have a separate spring in the centre, so if it goes lose, it’s a non issue as the spring will still provide a positive contact, if you don’t have this, go to another connection or don’t even consider the product. If you look at all the current of Silicon Chips Amplifiers, they have moved onto High quality Molex that are screw on type, even for the audio signal. Sadly, most products are built to a price and not a standard. Worse still are some makers of boutique / bespoke gear who can be pretty slack and inconsistent in the quality of their workmanship and often sold privately in classified advertisements on audio forums thereby effectively bypassing any safety approvals. It's no surprise that some people are foolish enough fall for the hype and "magic" surrounding these pieces of equipment. They are often believe they are buying a dream or something really special that sadly sooner or later turns into a nightmare that most repairers simply refuse to touch. 3
tesla13BMW Posted January 15, 2023 Posted January 15, 2023 When you say spade connectors are you talking the quick connect type on iec sockets and some monolithic bridges? If so these should all be soldered and shrink sealed? Or the U type that goes each side of a screw that is clamped down. My current safety concern is whether a thermal fuse is in Nuotem Talema 70041K. Can't find any mention of it.
Monkeyboi Posted January 15, 2023 Author Posted January 15, 2023 Crikey! Can it get any worse? Here's the PSU PCB. Some 1D10T has ground off the star grounding traces and replaced them with their own "improved" (LOL) version of the same. I have only one question - Why? There was already more than an adequate weight of copper there already. The Class A power amplifiers each only draw 1.65A nominal. The seriously deluded builder of this amplifier must have thought their effort of dry crystalised solder joints was a "superior upgrade" (ROFLMAO). What is so contradictory about this is the electrolytic capacitors are Nichicons and the resistors are Dales. Seriously, what is the rationale behind his or her thinking in using quality components but butchering the PCB in this way? Sorry, but I'm just lost for words at this point in time. I just fail to see how dry solder joints actually enhance an amplifier's performance. 2
Monkeyboi Posted January 15, 2023 Author Posted January 15, 2023 (edited) 1 hour ago, tesla13BMW said: When you say spade connectors are you talking the quick connect type on iec sockets and some monolithic bridges? Yes, see the attached photo of a typical female "spade" connector intended to be used to connect to these male spade terminals. They are colour coded for wire size identification purposes by an insulating sleeving and are intended to be used on stranded conductors. Three colours are in common use, these being red, blue and yellow. Red is for 0.75 to 1.0mm; blue for 1.5 to 2.5mm and yellow for 4.0 to 6.0mm diameter conductors. A red female spade terminal and a yellow eyelet type are shown in the photos for illustrative purposes. For wire gauges either smaller or larger than those mentioned above there are other crimp connectors available. I have included a photo of a much larger crimp connector intended for heavy gauge stranded cables. These are gauge size specific and any one lug only accommodates the gauge of conductors intended to be used in it. They are also crimped with a different tool with interchangeable dies than the automotive colour coded types previously mentioned. 1 hour ago, tesla13BMW said: If so these should all be soldered and shrink sealed? For the above colour coded examples shown, the short answer is no. Use the correct ratchet type crimping tool to do the job. The jaws of which are colour coded to suit the connector to be crimped. 1 hour ago, tesla13BMW said: Or the U type that goes each side of a screw that is clamped down. IME, the use of the U shaped or fork connectors is very limited. The downside is that the security and quality of the connection is entirely dependant on the screw securing it down. If the screw becomes loose so does the fork and all sorts of problems can occur. You're better off using the full eyelet type which can still come loose but unlikely to come completely adrift unless the screw securing it also does. Trick is to use with a shakeproof washer and secure the screw using a dob of suitable adhesive. 1 hour ago, tesla13BMW said: My current safety concern is whether a thermal fuse is in Nuotem Talema 70041K. Can't find any mention of it. Not all toroidal transformers have an internal thermal fuse. If they do, when the fuse ruptures you have to replace the transformer. Normally a manufacturer will specify the rating and type of external fuse to use with their particular model of transformer. It's good practice to ensure the correct fusing is used for safety purposes. Consult the manufacturer's datasheet for this information. If it's not available check their website or email them for technical assistance. Edited January 15, 2023 by Monkeyboi updated photo
tesla13BMW Posted January 15, 2023 Posted January 15, 2023 Thanks @Monkeyboi I was on the same page. I use a good pair of Ratchet Crimping Pliers and my female spade terminals have the contact spring. Re transformer the spec sheet says to fuse at 80mA which is 10VA/230V * 2. I'll have to reread Rod Elliots page on circuit protection https://sound-au.com/articles/fusing.htm as he says that low VA transformers Quote: Be warned and beware of small transformers (typically anything less than perhaps 10-15VA, lower ratings are progressively worse). Because these normally run with a partially saturated core, the calculated full load current cannot be used - it must be measured at full rated voltage. Likewise, the short circuit current must also be measured with the full mains voltage applied. While this will seriously overload the transformer, if tests are kept brief (as long as it takes to get an accurate measurement), the transformer will not be damaged. Make sure you allow time for it to cool to normal quiescent temperature between tests. From Rods contruction notes for the soft start circuit this 10VA transformer will be powering by switching the 9V secondary side Quote: One alternative that some constructors may find attractive is the ability to use a switch in the 9V secondary to power the amp on and off. This is (slightly) wasteful of power because the transformer is energised permanently (although idling current is generally quite small), and there is a small risk of fire. If you choose this method, the transformer must be fitted with a thermal fuse for your protection. As a responsible DIYer I read what I can. Shame is the other transformers (25VA) I'm using that aren't on all the time have thermal fuses and the one that needs it doesn't Oh well I have time to read more prior to finalising the power supply side of things. 1
Ihearmusic Posted January 15, 2023 Posted January 15, 2023 5 hours ago, Monkeyboi said: Well, not yet it hasn't, but given time IMHO it would have got a lot worse. Put it this way, it isn't going to be leaving here until it is fully electrically safe and compliant to AS/NZ standards. Unfortunately it is equipped with an IEC mains connector so simply cutting the mains cable off it isn't going to be a deterrent to someone simply plugging it into the wall outlet and powering it up. Whomever assembled the PCBs in this amplifier had no idea how to solder. I've attached some pics for your viewing pleasure. Beats me how it ever worked to begin with. Just for clarity I have taken these photos prior to me doing any fault finding or rework on the amplifier PCBs. There is some evidence that someone has already had a go at repairing these boards in the past. You can see fresher resoldering work albeit shiny balls of solder just sitting on the pads. Little silver apples. How they missed the obvious dry and fractured joints in beyond me. BTW, I know it's not generally considered good form to name and shame on SNA but feel free to PM me the name of the person who creates those preamps that you are referring to so I can actively avoid them in the future. In hindsight I now wish after taking a good look at this on the workbench that I should have just put the top cover back on it and declined the repair. Yes, that would have been the easy path but knowing how unsafe it is I couldn't in all honesty return it knowing the owner might very well attempt his own repairs and in doing so might have received a serious electric shock or even (heaven forbid) get electrocuted in the process. Agree on the "can of worms" comment. Most of the issues involving spade, eyelet and fork connectors is the failure on the part of the person fitting them to understand that the colour coding is relevant to the size of the conductors to be crimped and using the proper crimping tool. Way too many amateurs will probably purchase one of those "automotive crimp kits" on Ebay with an assortment of connectors and use those awful and practically useless el-cheapo crimping tools that comes in the box. All that "tool" does is damage the crimped section and the insulation surrounding it. Then they wonder why they don't work or fail shortly thereafter. I own two ME Sound products. An ME850HC power amplifier and an ME25 pre-amplifier. No spade connectors in either. In the ME850s Peter uses screw down terminations for all power related circuitry on Dinkle style PCB mounted connectors IIRC. I've also repaired a few ME850 power amps and haven't spotted any in them either. Those failures have mostly been with the ME branded electrolytic capacitors and one had a faulty logic gate IC on the power supervision PCB. I'm not sure if Peter used spade connectors in the past on other models but it's entirely possible he might have. My only negative critique of any connectors in ME gear is the audio ones. When my new ME850HC was deliver it was dead on one channel. The courier had given the crate it was shipped in somewhat of a hiding on its journey from FNQ to WA. One of the three pin connectors going from an input XLR to the PCB of the respective channel had come adrift in transit. Peter could have used a locking connector to overcome this from happening this but for some reason he didn't. I have subsequently retrofitted different connectors to both power amplifier PCBs so this won't happen again. Sadly, most products are built to a price and not a standard. Worse still are some makers of boutique / bespoke gear who can be pretty slack and inconsistent in the quality of their workmanship and often sold privately in classified advertisements on audio forums thereby effectively bypassing any safety approvals. It's no surprise that some people are foolish enough fall for the hype and "magic" surrounding these pieces of equipment. They are often believe they are buying a dream or something really special that sadly sooner or later turns into a nightmare that most repairers simply refuse to touch. F3 ?
muon* Posted January 15, 2023 Posted January 15, 2023 That PCB is scary! And that's coming from me! 1
bob_m_54 Posted January 15, 2023 Posted January 15, 2023 7 hours ago, Monkeyboi said: Yes, see the attached photo of a typical female "spade" connector intended to be used to connect to these male spade terminals. They are colour coded for wire size identification purposes by an insulating sleeving and are intended to be used on stranded conductors. Three colours are in common use, these being red, blue and yellow. Red is for 0.75 to 1.0mm; blue for 1.5 to 2.5mm and yellow for 4.0 to 6.0mm diameter conductors. A red female spade terminal and a yellow eyelet type are shown in the photos for illustrative purposes. For wire gauges either smaller or larger than those mentioned above there are other crimp connectors available. I have included a photo of a much larger crimp connector intended for heavy gauge stranded cables. These are gauge size specific and any one lug only accommodates the gauge of conductors intended to be used in it. They are also crimped with a different tool with interchangeable dies than the automotive colour coded types previously mentioned. For the above colour coded examples shown, the short answer is no. Use the correct ratchet type crimping tool to do the job. The jaws of which are colour coded to suit the connector to be crimped. IME, the use of the U shaped or fork connectors is very limited. The downside is that the security and quality of the connection is entirely dependant on the screw securing it down. If the screw becomes loose so does the fork and all sorts of problems can occur. You're better off using the full eyelet type which can still come loose but unlikely to come completely adrift unless the screw securing it also does. Trick is to use with a shakeproof washer and secure the screw using a dob of suitable adhesive. Not all toroidal transformers have an internal thermal fuse. If they do, when the fuse ruptures you have to replace the transformer. Normally a manufacturer will specify the rating and type of external fuse to use with their particular model of transformer. It's good practice to ensure the correct fusing is used for safety purposes. Consult the manufacturer's datasheet for this information. If it's not available check their website or email them for technical assistance. Of course don't use those crimpers on that 70-8 un-insulated lug at the bottom though... LOL 1
Monkeyboi Posted January 15, 2023 Author Posted January 15, 2023 2 hours ago, bob_m_54 said: Of course don't use those crimpers on that 70-8 un-insulated lug at the bottom though... LOL Absolutely. I recall the days when I was involved in large scale d.c. power installations we used to use hydraulic crimpers for the "Hylug" brand connectors for cables with conductors 10mm in diameter and larger. 2
Batty Posted January 15, 2023 Posted January 15, 2023 (edited) We have hydraulic crimpers at work for DC power in Subs. Edited January 15, 2023 by Batty 2
sloper Posted January 16, 2023 Posted January 16, 2023 l cant believe someone did that. Did the amp work? regards Bruce 1
Addicted to music Posted January 16, 2023 Posted January 16, 2023 22 hours ago, Monkeyboi said: . IME, the use of the U shaped or fork connectors is very limited. The downside is that the security and quality of the connection is entirely dependant on the screw securing it down. If the screw becomes loose so does the fork and all sorts of problems can occur. You're better off using the full eyelet type which can still come loose but unlikely to come completely adrift unless the screw securing it also does. Trick is to use with a shakeproof washer and secure the screw using a dob of suitable adhesive. I’ve never had screws go loose in any connections, high quality screw down type connections have spring washers, so if the screw go loose slightly it’s still in contact. All Clipsal electrical switches and connectors are all screw type without any washers. None have ever been a problem, not to me, that includes all your house electrical that has exactly this set up and no washers. Never seen them go lose and caused issues. Screw types are the most secure. The only time screws will go lose is if you have overtightened to the point where the thread is destroyed or it vibrates lose, if the connections are in a mobile environment experiencing vibrations and heat then you need to use a spring washer or a star washer. With components such as relays, filters and Full bridge rectifiers that have spade connections, I’ve seen it get soldered onto the pcb, others I’ve seen used high quality connectors that have an internal leaf spring or a raised dimple in the metal; this is what the hole in the middle of the male spade is for, the dimple locates into this hole and the plastic insulating case for the female are moulded so the construction ensure female never naturally open up and physically go lose. This is the way it’s been for a long time on Japanese. Equipment that are marketed world wide.. you never see the problem you have with other gear that haven’t caught up. What is an issue now is the IEC plug, a convenance for shipping products world wide but present a fire hazard on its own if it’s severely physically compromised. 1
Monkeyboi Posted January 16, 2023 Author Posted January 16, 2023 1 hour ago, sloper said: l cant believe someone did that. Did the amp work? regards Bruce Frankly nor can I. It's amazing it ever did, well at least for any length of time. Initial report from the owner is it wasn't working in one channel. Given the extremely dangerous way the 240v mains was wired into the chassis - switched on the neutral side only, oversized mains fuse and it had no protective earth on the metal chassis the first task was to make it safe to work on. I don't intend to get an electric shock off or get electrocuted from this thing whilst working on it albeit an isolation transformer would have made it safer. Considering the owner doesn't have an isolation transformer all these safety related issues have to be addressed in the first instance. At the first quick glance it initially didn't look too bad. I've seen worse, but after stripping it down the true shoddiness of the workmanship became painfully apparent. I have no idea who built it initially or who else had been there and done some failed rework what looks like an attempted repair on both amplifier PCBs. The toroidal transformer neoprene gaskets had been tightened down so tight they were pancaked to almost paper thickness in parts and in several spots actually penetrated through to the windings. Not in any way helped by the impregnated swarf from the drilling of the aluminium chassis. I did pop the question to the owner as to if they had built it themselves and the reply was no. In the gist of the conversation I got the impression it was originally constructed by an experienced DIYer. There was no mention as to who this was and I didn't ask.
Monkeyboi Posted January 16, 2023 Author Posted January 16, 2023 20 hours ago, Ihearmusic said: F3 ? Yes.
muon* Posted January 16, 2023 Posted January 16, 2023 56 minutes ago, Monkeyboi said: I did pop the question to the owner as to if they had built it themselves and the reply was no. In the gist of the conversation I got the impression it was originally constructed by an experienced DIYer. There was no mention as to who this was and I didn't ask. Not so experienced by the look of it 2
bob_m_54 Posted January 16, 2023 Posted January 16, 2023 12 hours ago, Monkeyboi said: Absolutely. I recall the days when I was involved in large scale d.c. power installations we used to use hydraulic crimpers for the "Hylug" brand connectors for cables with conductors 10mm in diameter and larger. Yep, I used to terminate cables from 25mm2 to 120mm2 on welding cable when I was repairing that sort of gear. But I also worked as an Auto Sparky for a couple of years doing mine vehicle upgrades and wiring.. Here's just a sample of the sh1tty work I've seen, all done by "professionals" Actually pic '3' is mislabelled.. what he'd done was used the rotary die type hand crimpers, with one die selected to 25mm and the other die set on the point between two dies, and used it as an indent crimper LOL The Lugs were fitted by a company that supplied pre-wired compressors for our mine service trucks. They were ordered that way by a new manager, who thought they would be wired more professionally than we would do it. hahaha.. Sheet, I used to wire up F-18s for f sake.. I sent him the pics to send to the company, and we got them un-wired after that.. And the solder job was done by an Auto Sparky we sub-contracted to do some of our mods, to extend the wiring harness on a Landcruiser to add trailer lights. He also used the cheap "Superchamp" style crimpers to install about 50 insulated lugs under the bonnet, and under the dash. About 50% of them pulled off by hand, and at least half of the rest were over crimped. The only reason we used him was because we had too much work on our plate at the time 3
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