- Mark Bass ,CMD 102P, bass amp of 2011 - 5 Updates
- STUPID QUESTION No. 5 - 3 Updates
- Fluke 8060a meter interconnect strip - 1 Update
- small motor "brush" material ? - 1 Update
| "Gareth Magennis" <soundserviceleeds@outlook.com>: May 12 08:34PM +0100 "N_Cook" wrote in message news:nh21r3$1c3$1@dont-email.me... Owner switched on, blue led came on as normal , but between that and 20 seconds grabbing guitar lead, had blown the mains fuse, no input, usual load. No problem in previous use, may be a drop in volume , as for the last month had to use 6 instead of 4 on the volume, but uses different cabs so cannot be certain of that. Both IRFP27N60K ohmic low all round. With trade mark ground off 8pin SMPS supervisor, from combined effort here a few years ago, probably IR2153 ,if like the other flavors of these amps. Any view as to what would cause this sort of failure? and pre-emptive mod around the supervisor circuit? I don't like the great thick slabs of ceramic insulator pads, should be used on bathroom splash-backs IMHO , not heat conductors. The main amps not checked over yet. Good luck with that. This is one manufacturer I refuse point blank to repair. Gareth. |
| N_Cook <diverse@tcp.co.uk>: May 12 09:08PM +0100 On 12/05/2016 20:34, Gareth Magennis wrote: > Good luck with that. > This is one manufacturer I refuse point blank to repair. > Gareth. At least a close enough schematic is on elektrotanya. I started looking at any common factor between the failed powerFETs. They are not symetrically disposed, but a 100V 33uF main +rail decoupler is physically near one failed FET and the other rail cap near the other FET. I'll check the ESR but will replace them anyway. Some sort of very large dV/dt or high level hf/rf that knocked out the adjacent FETs but got attenuated along the common lines to the other pairs of FETS perhaps.? Add some ferrite beads as well? Needs something adding , instead of just replacing the expensive powerFETs especially if the caps ESRs are good |
| "Gareth Magennis" <soundserviceleeds@outlook.com>: May 12 11:02PM +0100 "N_Cook" wrote in message news:nh2nlv$n5q$1@dont-email.me... On 12/05/2016 20:34, Gareth Magennis wrote: > Good luck with that. > This is one manufacturer I refuse point blank to repair. > Gareth. At least a close enough schematic is on elektrotanya. I started looking at any common factor between the failed powerFETs. They are not symetrically disposed, but a 100V 33uF main +rail decoupler is physically near one failed FET and the other rail cap near the other FET. I'll check the ESR but will replace them anyway. Some sort of very large dV/dt or high level hf/rf that knocked out the adjacent FETs but got attenuated along the common lines to the other pairs of FETS perhaps.? Add some ferrite beads as well? Needs something adding , instead of just replacing the expensive powerFETs especially if the caps ESRs are good Yeah, yeah yeah. That's why I won't repair this stuff. Gareth. |
| N_Cook <diverse@tcp.co.uk>: May 13 09:14AM +0100 good ESR and uF value of those 2 caps and the main ps rail caps. Thin ground traces going to those 33uF caps, so looks like some of those otherwise mysterious retrofit pieces of overlain wires will be going in there. |
| N_Cook <diverse@tcp.co.uk>: May 13 03:20PM +0100 At least there is vertical clearance on the pins of the replacement audio TOP-3, to slide on some ferrite beads. |
| Jon Elson <jmelson@wustl.edu>: May 12 03:01PM -0500 Jeff Liebermann wrote: > All inks fade, rub off, or take too long to dry. What you want are > Kroy thermal transfer labels for marking wires. > <http://www.kroy.com/thermal/index.htm> Brother makes label products that laminate the label behind the front layer of the lamination. These are their "TZ" tapes. The make a "super flexible" version that can be wrapped around wires. Might still need some clear tape or something to make them stay on forever. I use one of these for serial # labels and such, so I have the machine already. Jon |
| avagadro7@gmail.com: May 12 05:43PM -0700 hmmm possible to buy quality wire labels as Kroy with numbering on the labels peel off label 0001A and affix, write down what 0001A is in the book. write down where book is.... . |
| Jeff Liebermann <jeffl@cruzio.com>: May 12 08:16PM -0700 >hmmm possible to buy quality wire labels as Kroy with numbering on the labels >peel off label 0001A and affix, write down what 0001A is in the book. >write down where book is.... I did that at one office building: Before: <http://802.11junk.com/jeffl/pics/drivel/slides/Phone%20Room%20Before.html> After: <http://802.11junk.com/jeffl/pics/drivel/slides/Phone%20Room%20After.html> Well, that photo was before I labeled everything. The problem was that it only worked as long as I was personally doing the wiring. When the phone, alarm, sprinkler, cable company, self-installers, etc arrived, they made a huge mess. Asking Ma Bell to "tag" their work seemed to be like asking the installer to perform an un-natural act. I gave up. Well, if you want quality and a permanent label, I suggest a Kingsley (Norwood) hot stamp machine: <https://www.youtube.com/watch?v=CcjwVgQNqTg> <https://www.itwnorwood.com> If that's not good enough, there are laser wire warker machines: <https://www.youtube.com/watch?v=k81ISpP2pc4> or maybe an ink sprayer: <https://www.youtube.com/watch?v=RNyfFnKWaJ0> You can also use it to apply fake tatoos. -- Jeff Liebermann jeffl@cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
| Jeff Liebermann <jeffl@cruzio.com>: May 12 04:31PM -0700 >> spiral, the different pitch, and that the 8024a screw is a bit larger >> diameter. Which style does your 8060A use? >The screws from my IBM 8060A are the double helix. Thanks. Those are almost impossible to find. I think it's a #7-19 3/4" High Low Thread Forming Screw. Digging: <http://www.eaglefastener.net/technical/hilo-fastener-table.html> My digital calipers claims it's a #7-19 and 19 tpi which seems about right. Nothing on eBay. I can't seem to find any that I can order, but will continue digging. I also need to verify the size, which seems rather odd. >The screws I sent >you did not actually come from my 85, but from a newer 77. Sigh. So I have to change my JPG again. Grumble(tm). >When asking around if anyone had any dead Flukes (trying to locate >that p-jfet for my 85), If I have time, I'll try to identify the JFET for the Model 85. What is the reference designator so I know which one? >I was given a 77 that was blasted by a microwave oven. I just can't resist the temptation. What the [deleted explitive] was someone thinking when they put the DVM in the oven? Is this the same person that tried to dry their poodle in the micrwave? >The 77 didn't have the jfet I needed so I ended up fixing the 77 >and returning it to the donator as a gift, but not before swapping >the screws with some generic screws I had as payment :). Nicely done. >Those I sent to you because there were three and I only had two >from the 85. Whew! Thanks again. I have about 5 assorted Fluke meters scattered around. Most are held together with one screw and a rubber band. Most are the older models, which take the high-low thread forming screws. I hadn't planned on doing this for a while, but I guess now that I've started, it's time to replace the missing parts, fix any battle damage, clean the crud out of the guts, and calibrate the meters. >When I removed the chip from the socket, I found there was no >corrosion evident but two of the tangs in the socket came apart, >so I ordered a new socket and put the repair on hold until it arrives. I have a bunch of these, which methinks will work (after I check the height). I had the same problem with the existing socket. Where the corrosive goo from the electrolytic or water rotted out the socket, one of the contacts fell out. However, I cleaned the other contact, which still works... for now. I guess I should stock up on replacment electrolytics and just do a pre-emptive replacement. Sigh, the project grows. -- Jeff Liebermann jeffl@cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
| MJC <gravity@mjcoon.plus.com>: May 12 10:36PM +0100 In article <f6e561cf-16a8-4d0b-b2ab-bb4f200d10d6@googlegroups.com>, pfjw@aol.com says... > Those fingers are spring bronze, very thin and relatively hard to duplicate as the bronze alloy is a delicate balance between being too hard and not having enough spring. Too hard would eat into the commutator, not hard enough would anneal and fail quickly. Back in the 1950s (I guess) when my Dad and I were playing with toys, we also thought that a small motor had phosphor-bronze spring brushes. Having no idea where to get stock metal we tried cutting up slices from a roll sold by a local hardware as draught-prevention seals for doors etc. I don't remember how durable it was! Not sure if it is the same stuff, but I have some more recent "Atomic Weather Strip" made of "specially prepared copper alloys" and carrying a ten year life time... Mike. |
| You received this digest because you're subscribed to updates for this group. You can change your settings on the group membership page. To unsubscribe from this group and stop receiving emails from it send an email to sci.electronics.repair+unsubscribe@googlegroups.com. |
1 Response to Digest for sci.electronics.repair@googlegroups.com - 10 updates in 4 topics
Using laser marking technology has many advantages. It has high carving accuracy, hollow hairless edges, and different shapes. It is fully satisfied with the idea that everyone seeks independent characteristics today. It can be suitable for a variety of materials. Wuhan Raymond laser marking machine is a surprise gift. Its high power and low cost advantages can enable many manufacturers to quickly occupy the market and improve the competitive advantage of the industry.https://www.raymondlaser.com
Post a Comment