- PbF and eyelets - 12 Updates
- VGA to composite or S converter problems - 2 Updates
- Revox A722 - 1 Update
| N_Cook <diverse@tcp.co.uk>: Dec 16 05:07PM Third time in as many months, usual PbF phantom problems, solder looks fine but no wetting between eyelet and pin and grey (tinpest?) pin, even after desoldring. Other repairers regularly finding this failure mechanism also? This time 2009 Revera Fandango valve amp . Needless to say problem is with one of the combined pot and pull-switch , awkward to desolder. So what is the function of eyelets other than to bridge gaps in pcb holes, for resourced components with smaller pins than original source , and so incompatible with pcb drillings otherwise , for stuctural solder integrity. Perhaps with proper solder they made more robust joints but for RoHS times ? |
| N_Cook <diverse@tcp.co.uk>: Dec 16 06:58PM 8 of 9 eyelets stayed on the component on desoldering, the duff one stayed in the pcb, its pin neatly sliding out of the eyelet. |
| "pfjw@aol.com" <pfjw@aol.com>: Dec 16 11:11AM -0800 On Friday, December 16, 2016 at 12:07:12 PM UTC-5, N_Cook wrote: > Third time in as many months, usual PbF phantom problems, solder looks > fine but no wetting between eyelet and pin and grey (tinpest?) pin, even > after desoldring. I will render an opinion here based on my experiences with conventional lead-containing solder of differing natures. a) Non-Eutectic solders will solidify in a non-linear fashion as it cools. b) My experience with 60/40 and 50/50 solders with wires is that the cooling is often based on the wire as it is a heat-sink. c) Dynaco equipment uses a lot of eyelets set in circuit boards. d) Using solders as described above, on more than one occasion I have gotten visually excellent connections that simply twirl in the eyelet, as the solder cooled (dumped heat into the wire) so fast that the shrinkage pulled it away from the eyelet before it was actually solid. This is purely anecdotal. Today, I use only truly eutectic solders on my electronics (37/63 lead/tin) - with a very few exceptions, when for one reason or another I need to use silver bearing solder. In those cases, I use 96/4 tin/silver, and great care not to move anything as it cools. Peter Wieck Melrose Park, PA |
| amdx <nojunk@knology.net>: Dec 16 05:29PM -0600 > Today, I use only truly eutectic solders on my electronics (37/63 lead/tin) - with a very few exceptions, when for one reason or another I need to use silver bearing solder. In those cases, I use 96/4 tin/silver, and great care not to move anything as it cools. > Peter Wieck > Melrose Park, PA I had an eyelet problem 30 years ago on my Philips CD player. I couldn't fix it, so I sent it to Philips Repair. I worked at an authorized service center at the time. The sent it back saying they could not fix it. I mentioned it to a fellow tech and he said, "let me look at it". He put a wire through each eyelet and soldered both sides. That corrected the problem. Mikek |
| M Philbrook <jamie_ka1lpa@charter.net>: Dec 16 06:40PM -0500 In article <o31tao$52n$1@dont-email.me>, nojunk@knology.net says... > He put a wire through each eyelet and soldered both sides. > That corrected the problem. > Mikek a via ? |
| amdx <nojunk@knology.net>: Dec 16 07:32PM -0600 On 12/16/2016 5:40 PM, M Philbrook wrote: >> That corrected the problem. >> Mikek > a via ? Well, it's been over 30 years so it could have been vias, but I recall it as eyelets. I still have it I guess I could open it up. Naw, to much trouble to get it out of the closet. Mikek |
| N_Cook <diverse@tcp.co.uk>: Dec 17 08:23AM > Today, I use only truly eutectic solders on my electronics (37/63 lead/tin) - with a very few exceptions, when for one reason or another I need to use silver bearing solder. In those cases, I use 96/4 tin/silver, and great care not to move anything as it cools. > Peter Wieck > Melrose Park, PA I suppose part of the problem, the pins are square cross-section , not round. Then localised stressing edges for tinpest to develop. Remedial action will start by grinding back to an axial surface on all such pot pins, on the solder side of the pcb before resoldering. Then what other components will be eyeleted as well will need such attention, the main electros yes, minor electros will they be eyeleted , 1W and above Rs also, difficult to visually tell. I suppose the rule is anything big is likely to be eyeleted, plus any component resource with smaller pins. |
| N_Cook <diverse@tcp.co.uk>: Dec 17 08:25AM On 16/12/2016 23:29, amdx wrote: > He put a wire through each eyelet and soldered both sides. > That corrected the problem. > Mikek If you can thread wire through, I'd call those vias. |
| ohger1s@gmail.com: Dec 17 02:26AM -0800 On Friday, December 16, 2016 at 6:29:52 PM UTC-5, amdx wrote: > He put a wire through each eyelet and soldered both sides. > That corrected the problem. > Mikek Motorola had their "famous" Placir printed circuits in the 60s, and they were notorious for connection problems between the top and bottom layers. The only solution to permanently repair these was to hard wire the top to bottom. GE in the 70s had a line of TVs that used double sided boards with hollow griplets crimped through the board and covered with a thin layer of solder, and these would develop a dozen or more gimpy connections. Flexing the main board would cause all sorts of color, sync, brightness, video, sound issues etc. Resoldering them was difficult because the boards would out-gas badly when the griplets were heated causing cold joints. Instead of hand wiring the 50 or more griplets, I solder one side thoroughly feeding in lots of solder, turn the board over and remove the excess solder that came through, resolder that side thoroughly, and turn it over again and reflow a third time. The outgassing usually stopped by the second pass. They never came back after that. |
| jurb6006@gmail.com: Dec 17 02:32AM -0800 >" I mentioned it to a fellow tech and he said, "let me look at it". He put a wire through each eyelet and soldered both sides. " I am not straight on this eyelet thing. Does that mean the plated through holes ? If it is like a rivet type thing they used to be called griplets. They used them in some TVs with two sided boards that were not plated through holes. They used to break free and wreak havoc. Then we got the plated through holes without anything in them. What your buddy did might be called "pinning". Turns out some of the Dolby boards on the Sansui 9090DB went bad this way some audiophiles consider this pinning to be an essential part of the restoration process. It seems that on some boards the eyelets or griplets simply forestall the problem, not prevent it. |
| N_Cook <diverse@tcp.co.uk>: Dec 17 02:08PM A good dialect word for the appearance of PbF - claggy, a conflation of clumpy and slaggy |
| jurb6006@gmail.com: Dec 17 08:17AM -0800 >"Resoldering them was difficult because the boards would out-gas badly when the griplets were heated causing cold joints." We learned to cookem. Seriously, lay the iron on it and watch it bubble for a while. Some of them eventually stopped bubbling but some didn't. Those that didn't were usually sufficiently cooked to work. I remember those AB chassis'. Now, they wouldn't even be considered for repair or anything like them. Even a flat screen that size today, if it is not fixed in five minutes it goes into the dumpster. But that was then. |
| Chuck <chuck@mydeja.net>: Dec 16 10:46AM -0600 On Thu, 15 Dec 2016 14:28:39 -0800 (PST), captainvideo462009@gmail.com wrote: >> I needed to convert the VGA output from my laptop to either S or composite video. I purchased this converter and although I can get it to display on the video monitor the picture appears as though the vertical is running off frequency. Naturally there is no way to adjust this on most equipment these days. And there does not seem to be any way the address this in the converter either. I tried selecting different refresh rates and resolution settings on the computer but nothing seems to make a difference. Does any one have any ideas? Thanks, Lenny. >> http://www.ebay.com/itm/VGA-to-TV-RCA-Composite-Converter-Adapter-S-video-Box-for-PC-Laptop-Windows-Mac-/111867988250?fromMakeTrack=true >I've never tried it but it's doubtful. I've tried to get CBS from Burlington before and I didn't even get pixels. With our elevation Boston is bad enough but Burlington would be a haul for me. I have somewhat of a shot at Southeastern Maine but even Portland would be a stretch. Lenny Lenny, If you have a PC , right click on the desktop and click on screen resolution. Set for 640 X 480 if possible. Otherwise set at 1024 X 768 or 800 X 600. You also need to set the screen refresh rate at 60 hz. This is in advanced settings in the screen resolution window. Chuck --- This email has been checked for viruses by Avast antivirus software. https://www.avast.com/antivirus |
| Chuck <chuck@mydeja.net>: Dec 16 10:54AM -0600 >--- >This email has been checked for viruses by Avast antivirus software. >https://www.avast.com/antivirus The screen refresh rate is under the monitor tab. --- This email has been checked for viruses by Avast antivirus software. https://www.avast.com/antivirus |
| Chuck <chuck@mydeja.net>: Dec 16 10:49AM -0600 On Thu, 15 Dec 2016 06:49:59 -0800 (PST), "pfjw@aol.com" >The tiniest bit of the wife's clear fingernail polish eliminated that issue without causing future servicing issues. I purchased my unit in nearly unused condition for very little as the owner was upset with it for just that reason. US$100 in 2001. It was on a local for-sale bulletin board where I worked. I offered to fix it for him, but he was done with cassettes by then. >Peter Wieck >Melrose Park, PA Revox came out with a service bulletin about a year later to inform service centers that they had a more reliable reel table. We recalled all that we sold and replaced the tables. --- This email has been checked for viruses by Avast antivirus software. https://www.avast.com/antivirus |
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