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"Gareth Magennis" <soundserviceleeds@outlook.com>: Nov 04 09:07PM OK, so I want to clone this inductor, L9.   http://elektrotanya.com/digipro_1000_sch_pcb.pdf/download.html     It is wound on a ETD29 former, I have counted the turns and the wire gauge.   What I don't know is the core material. There are several types available.   (The original has zero gap in the core)   This is a reasonably high power SMPS, running a powered speaker. http://www.rcf.it/products/pro-speaker-systems/art-7-series/art-710-a       How would one determine the type of core used in this design?     Cheers,     Gareth.

Phil Allison <pallison49@gmail.com>: Nov 04 08:13PM -0700 Gareth Magennis wrote:   > It is wound on a ETD29 former, I have counted the turns and the wire gauge.   > What I don't know is the core material. There are several types available.   > (The original has zero gap in the core)   ** You sure it has no gap ???   L9 is a PFC choke and they use powdered iron cores or gapped ferrite.   Normally, the middle leg is ground short to create a gap of up to 1mm to allow DC current to pass without saturating the ferrite. Un-gapped ferrite cores are good for push pull, square wave transformers only.   You have the original core, so can measure its inductance and have a damn close look for the missing GAP.   Meanwhile, this link should supply some useful clues.   http://www.tme.eu/en/Document/d3a1e827773837de0340fb075548fa6f/etd_29_16_10.pdf     ..... Phil

"Gareth Magennis" <soundserviceleeds@outlook.com>: Nov 05 09:21AM "Phil Allison" wrote in message news:4adf249b-7d2b-4450-890a-f736e0b2f96a@googlegroups.com...   Gareth Magennis wrote:   > What I don't know is the core material. There are several types > available.   > (The original has zero gap in the core)   ** You sure it has no gap ???   L9 is a PFC choke and they use powdered iron cores or gapped ferrite.   Normally, the middle leg is ground short to create a gap of up to 1mm to allow DC current to pass without saturating the ferrite. Un-gapped ferrite cores are good for push pull, square wave transformers only.   You have the original core, so can measure its inductance and have a damn close look for the missing GAP.   Meanwhile, this link should supply some useful clues.   http://www.tme.eu/en/Document/d3a1e827773837de0340fb075548fa6f/etd_29_16_10.pdf     ..... Phil                 Thanks Phil, I'm pretty sure it has no gap. It's almost impossible to take these things apart without breaking the very fragile core. I've kept all the bits so will go back and glue them together to recheck this. I've taken apart other SMPS transformers where the gaps are quite obvious, even with a core in several pieces, and measurable with a micrometer without having to reassemble.     One other thing, Digipro use enamelled stranded wire on this inductor. I gather this has better HF performance than the much more common solid copper enamelled wire. A quick look for stranded enamelled wire of this guage on the Interweb yesterday showed it is not widely available in small amounts.   Would you need to adjust the number of turns if you used solid copper instead?       BTW, this seems to be a common failure mode of these Digipro amps - this is the second I have seen. The windings short together, and there is no insulation or tape applied anywhere on the windings except the final outer wrap.     Cheers,     Gareth.

MJC <gravity@mjcoon.plus.com>: Nov 05 10:59AM In article <PwhTz.228621$9L.134016@fx26.am4>, soundserviceleeds@outlook.com says... > solid copper enamelled wire. > A quick look for stranded enamelled wire of this guage on the Interweb > yesterday showed it is not widely available in small amounts.   Did you search under the name "Litz wire"? (That's just something dredged up from my electronics of decades ago.) I just got some hits, but did not look for suppliers...   Mike.

Phil Allison <pallison49@gmail.com>: Nov 05 04:11AM -0700 Gareth Magennis wrote:   > Meanwhile, this link should supply some useful clues.   > http://www.tme.eu/en/Document/d3a1e827773837de0340fb075548fa6f/etd_29_16_10.pdf   > I'm pretty sure it has no gap.   ** There is one - it might be only a few thou of an inch, but it must be there or the whole thing would blow up.       > I've taken apart other SMPS transformers where the gaps are quite obvious, > even with a core in several pieces, and measurable with a micrometer without > having to reassemble.   ** This is NOT a SMPS transformer, it's a ferrite CHOKE that must pass a couple of amps of DC current. It simply HAS to have an air gap !!!     > yesterday showed it is not widely available in small amounts.   > Would you need to adjust the number of turns if you used solid copper > instead?     ** FFS, make your own stranded wire.   Dare to be great !!!!!!     > the second I have seen. The windings short together, and there is no > insulation or tape applied anywhere on the windings except the final outer > wrap.   ** Use higher temp wire, 220C stuff is readily available, the usual magnet wire is only rated at 120C at best.   Do not muck about: an active, high frequency, PFC choke is critical component.       .... Phil

"Gareth Magennis" <soundserviceleeds@outlook.com>: Nov 05 03:53PM "Phil Allison" wrote in message news:148f351c-485f-42bf-a61b-82ec730ce66a@googlegroups.com...   Gareth Magennis wrote:   > Meanwhile, this link should supply some useful clues.   > http://www.tme.eu/en/Document/d3a1e827773837de0340fb075548fa6f/etd_29_16_10.pdf   > I'm pretty sure it has no gap.   ** There is one - it might be only a few thou of an inch, but it must be there or the whole thing would blow up.     > even with a core in several pieces, and measurable with a micrometer > without > having to reassemble.   ** This is NOT a SMPS transformer, it's a ferrite CHOKE that must pass a couple of amps of DC current. It simply HAS to have an air gap !!!     > yesterday showed it is not widely available in small amounts.   > Would you need to adjust the number of turns if you used solid copper > instead?     ** FFS, make your own stranded wire.   Dare to be great !!!!!!       > the second I have seen. The windings short together, and there is no > insulation or tape applied anywhere on the windings except the final outer > wrap.   ** Use higher temp wire, 220C stuff is readily available, the usual magnet wire is only rated at 120C at best.   Do not muck about: an active, high frequency, PFC choke is critical component.       .... Phil                 Well there's my biggest problem, then. Unless I know what the original core material is, I can't make one the same, the original core is in pieces. It may not be any of the TDK formulations I can buy at Farnell.   And I guess I would need to use the same type of wire, not solid enamelled. (or possibly rescue/repair and re-use the old winding)       Gareth.

"Gareth Magennis" <soundserviceleeds@outlook.com>: Nov 05 03:57PM "MJC" wrote in message news:MPG.3287cbd3ace2f30432@news.plus.net...   In article <PwhTz.228621$9L.134016@fx26.am4>, soundserviceleeds@outlook.com says... > solid copper enamelled wire. > A quick look for stranded enamelled wire of this guage on the Interweb > yesterday showed it is not widely available in small amounts.   Did you search under the name "Litz wire"? (That's just something dredged up from my electronics of decades ago.) I just got some hits, but did not look for suppliers...   Mike.               Thanks for that info, Mike.   Gareth.

"pfjw@aol.com" <pfjw@aol.com>: Nov 04 11:36AM -0700 It would interest me more on the 4th band (if any) color. 10% on 150 = 165 to 135. 20% = 180 to 120. Unmarked generally means 20%.   Peter Wieck Melrose Park, PA

N_Cook <diverse@tcp.co.uk>: Nov 04 06:49PM > It would interest me more on the 4th band (if any) color. 10% on 150 = 165 to 135. 20% = 180 to 120. Unmarked generally means 20%.   > Peter Wieck > Melrose Park, PA   Its not a tolerance thing, gold fourth band. R67 and R66 are exactly the same resistor batch, the green of the heat aged one is now not green, its value is now not 150R

"pfjw@aol.com" <pfjw@aol.com>: Nov 05 05:11AM -0700 On Friday, November 4, 2016 at 2:49:16 PM UTC-4, N_Cook wrote:   > Its not a tolerance thing, gold fourth band. > R67 and R66 are exactly the same resistor batch, the green of the heat > aged one is now not green, its value is now not 150R   You miss my point. Resistors drift, true. And the resistors in place seem to be undersized (operative word "seem") You intend to to replace them with higher-watt devices that are at the correct value. All good, so far.   But, I am asking whether the circuit itself may be tolerant of that drift - hence the question on band 4 - if any.   Peter Wieck Melrose Park, PA

N_Cook <diverse@tcp.co.uk>: Nov 05 01:16PM > But, I am asking whether the circuit itself may be tolerant of that drift - hence the question on band 4 - if any.   > Peter Wieck > Melrose Park, PA   The schematic for seemingly all these amps , minor variations, is on Electrotanya as Parsek Mark Bass Little not all the fan current goes through this R67 and without measuring some actual circuit nodes on this amp and modelling the schematic I don't know how much current is actually now or should be taken by the MJE340, but something is not hunkey dorey. Note the refs to 2W and 5W on that schematic,R67 and R67, in reality exactly the same size , colour body , shape on this amp

Cydrome Leader <presence@MUNGEpanix.com>: Nov 04 08:35PM > Take the T12 ballasts I have, for example, which are made in New Jersey. > That doesn't mean they're high quality, just because they're made in the > USA, does it?   We can deduce they were made good enough to last a couple decades.   > it's made.   > For example, is there *any* indication of the quality of the Costco Feit > lamps that I bought?   yes, what you paid for them, and the fact there's no real spec sheet on them.   > Here's the spec sheet, I think: > http://www.feit.com/documents/pdf/T4819_LEDIF_41K_SpecSheet.pdf   As far a lighting goes, that's a 100% meaningless spec sheet. It doesn't even mention the CRI, which is guaranteed to be unspecified anywhere and not controlled.   > NOTE: Tomorrow I'll ask Feit for the LM-79 and LM-80 data.   > What do you think about the quality of these Feit lamps, made in China?   cheapest imported lighting would be the best description.

Bill Moinihan <moi@example.com>: Nov 05 12:38PM Cydrome Leader wrote:   > We can deduce they were made good enough to last a couple decades.   Good point, in that they were made well enough to last for probably 30 years.   > yes, what you paid for them, and the fact there's no real spec sheet on > them.   No. No. No. No. No. No. No. No. No. No. No. No. No. No. No. No. No. No. What you paid is NEVER an indication of quality.   I can give you hundreds of examples which nullify instantly that idiotic argument. I've been having this argument for years, with many people, so, please understand that it's not you that I'm upset with.   I'm upset with people who can't THINK about DETAILS, so they pick a SIMPLE number as their indicator of quality.   Sure, price is a SIMPLE way to think about things. So is warranty.   But neither is ANY indication whatsoever of quality.   Sure, some quality stuff costs more, but a LOT of things are overpriced (e.g., lettuce at safeway, housing in California, HP ink cartridges, etc.).   None of those are high quality.     > As far a lighting goes, that's a 100% meaningless spec sheet. It doesn't > even mention the CRI, which is guaranteed to be unspecified anywhere and > not controlled.   I agree with you that this so-called "spec" sheet was just marketing fluff. But I had nothing better on the net. That's why I asked.   > cheapest imported lighting would be the best description.   On the one hand, you realized the "spec" sheet was BS, but on the other hand, you make quality decisions based on a single nearly meaningless number, simply because it's easy to do.   SO I'm confused by your advice.

jurb6006@gmail.com: Nov 04 04:13PM -0700 What you said, or reranted is not wrong in some instances. One notable exception is audio amps that use VFETS for outputs, which are depletion mode and WILL fry if you try to run the up slow on a variac, at least in the Sony ones. I don't know of any others but to be tolerant of low AC input it would take a quite special design with abnormal conditions in mind. I worked for a Sony Signature dealer and ASC back before their product turned to real shit and I can tell you that i n most cases, abnormal conditions were not on their engineers' minds.   Dim bulbs and variacs come in handy when you have repaired most regular solid state amplifiers. Once you drop $35 worth of silicon in them for a fried channel it is nice not to have all that short out in the first millisecond.   With most tube stuff, honestly I would just plug it in. Possible exceptions would be if it has selenium rectifiers. Even moreso a high end tube amp with a big old 5U4 but using a selenium rectifier for the negative bias to the outputs.   Bottom line is you can't just make a blanket statement about working on all equipment. And with the advent of the SMPS, there are even less assumptions that can be made. You can usually use a DBT on like a DVD player or something like that and it will keep the smoke in in most cases. But the normal current drain is usually so low all a hundred watt bulb will do is keep you from burning foil off the PS board. Some short on the five volt line is not protected and if it is going to fry something it is going to succeed. Then, if you use a lower wattage bulb, some SMPSes won't start.   Before I got kicked off AK they were always talking about the DBT. And really it does prevent pretty much all board burning. You burn the foil of a circuit board it is not fun to fix, especially with audiophiles who are going to want your repair to follow the same path as the original foil. I have done that type of rework but really most of the shit today does just fine with jumper wires.   Lately I am dealing with a design defect in amps built by Apex for RSQ, KDS and Technical Pro. All a bunch of liars on the power specs, Technical Pro claims like 1,300 watts or something on an amp that actually puts out about 90 watts a channel. The defect is that the assholes thought the bias regulator would just hold itself to the heatsink. Well they don't, and now ater going through several options we just could not make happen I am simply gluing them. Got me some JB Weld and made some clamps out of a couple of coat hangars. How is that for factory service ?   Enough rant, back to the subject. The DBT and variac have actually lost some of their usefulness. They are not useless but it does depend on what you are working on. Old tube stuff I would just plug in. For a few seconds. then I would remove all the tubes ad plug it in for longer. then I would put in the rectifier tube and see what happens to the current draw, with all the other tubes out. Scope the caps, if all the other tubes are not in there and you got ripple you got a problem. Turn if off before you blow that 5U4, which is no longer available for $3. The shipping is more than $3.   I have had a pretty diverse career and even got a little bit into CNC machines but not much. I learned automotive electronics when they started with those ECMs and shit. We flipped cars, and the reason we made money was because the backyard mechanics could not understand electronic and My Goodwrench forgot there was an actual engine under all that shit. I beat them several times in troubleshooting. Three of them making fifty bucks an hour looking at a computer readout and can't tell you have a burnt valve or a fouled plug. And the idiots probably made more money than me.   If you think powering up old electronics is scary, try starting an old car that has been sitting for 20 years or more. That's why some people actually take them apart first.   Well not completely apart but they will do a compression check, change the oil, whatever they can coax out of the crankcase that is and put new oil in it, drain the gas tank, pressure check the cooling system maybe, but that can come later after the thing actually starts.   Everything requires a slightly different approach.

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