sci.electronics.repair@googlegroups.com

Google Groups

bitrex <bitrex@de.lete.earthlink.net>: May 01 01:38PM -0400 On 05/01/2016 11:14 AM, bitrex wrote: > connections, reflowed the solder joints to the headers but still > no luck.   > Can anyone suggest a methodical way to isolate where the problem is?   I have a suspicion this might not be a mechanical issue. The connector I'm actually yanking on is 34-52, on page 18 of the service manual, labeled "Cartridge Board."   I swapped out a resistor that's connected to ground from the LCD display to increase the contrast, changed from 5.6k to 1k. That resistor is right next to IC20, which is connected to the "Cartridge Board" read/write lines.   I wonder if that bollocked something up, because the synth didn't have this issue prior to the LCD swap.   I don't see any obvious solder bridges but I'll look again...

Jeff Liebermann <jeffl@cruzio.com>: May 01 10:45AM -0700 On Sun, 1 May 2016 11:14:50 -0400 (EDT), bitrex   >Can anyone suggest a methodical way to isolate where the problem is?   Find which wire on the connector is not making a connection. Power off. Attach wire hooks or tack solder some wires to opposite sides of the connector. Attach an ohmmeter. Now, wiggle things around until you determine where things are intermittent.   A close photo of the connector area would be helpful if you want me to make a guess(tm).   I couldn't find 67 - 74 on the main board schematic (Pg 18). That are the row and column coordinates or maybe a large nearby component?           -- 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

bitrex <bitrex@de.lete.earthlink.net>: May 01 01:47PM -0400 On 05/01/2016 01:45 PM, Jeff Liebermann wrote: > make a guess(tm).   > I couldn't find 67 - 74 on the main board schematic (Pg 18). That are > the row and column coordinates or maybe a large nearby component?   I think the problem may not be mechanical, as I've noticed that now the keyboard is having issues triggering as well, which is not connected to the same area.   I think I screwed something up swapping R66 on page 18 near the LCD, and the processor is having trouble with read/writes or something.

Jeff Liebermann <jeffl@cruzio.com>: May 01 10:58AM -0700 On Sun, 1 May 2016 13:47:13 -0400, bitrex   >I think the problem may not be mechanical, as I've noticed that now the >keyboard is having issues triggering as well, which is not connected to >the same area.   Well, it wouldn't hurt to eliminate the keyboard as a possibility. Put an ohmmeter across a row and column on the keyboard and measure the contact resistance with an ohmmeter. Try all the button combinations. If the resistance seems resonable, move on to looking for another culprit.   >I think I screwed something up swapping R66 on page 18 near the LCD, and >the processor is having trouble with read/writes or something.   5.6K goes to Vo on the LCD display, whatever that does. If it's carbon comp, check the resistance with an ohmmeter. They change over time and absorb moisture. However R66 doesn't seem to go anywhere except the display making changes to keyboard and buttons rather unlikely. Dunno.     -- 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

bitrex <bitrex@de.lete.earthlink.net>: May 01 02:31PM -0400 On 05/01/2016 01:58 PM, Jeff Liebermann wrote: > time and absorb moisture. However R66 doesn't seem to go anywhere > except the display making changes to keyboard and buttons rather > unlikely. Dunno.   R66 controls the contrast of the LCD. I had to swap it out as the new LCD display didn't seem to be 100% compatible, and it was invisible with the stock 5.6k resistor. 1k makes it legible again.   R66 is sitting about half a millimeter away from the deglitching cap for IC20. I'm looking to see if I might have bridged it somehow.

"pfjw@aol.com" <pfjw@aol.com>: May 01 11:37AM -0700 On Sunday, May 1, 2016 at 12:49:54 PM UTC-4, bitrex wrote:   > > Peter Wieck > > Melrose Park, PA   > ?   Press down on each separate wire as it goes into the MPC. A spade-type dental tool is excellent for this purpose. The point being that if the connector holds when under stress, but fails when there is no stress, it is very most likely mechanical.   And, of course, it could be two-or-more things if you, in fact, bridged something replacing a resistor.   Peter Wieck Melrose Park, PA

"Gareth Magennis" <soundserviceleeds@outlook.com>: May 01 07:46PM +0100 "bitrex" wrote in message news:tarVy.6021$IU7.3901@fx19.iad...   On 05/01/2016 11:14 AM, bitrex wrote: > connections, reflowed the solder joints to the headers but still > no luck.   > Can anyone suggest a methodical way to isolate where the problem is?   I have a suspicion this might not be a mechanical issue. The connector I'm actually yanking on is 34-52, on page 18 of the service manual, labeled "Cartridge Board."   I swapped out a resistor that's connected to ground from the LCD display to increase the contrast, changed from 5.6k to 1k. That resistor is right next to IC20, which is connected to the "Cartridge Board" read/write lines.   I wonder if that bollocked something up, because the synth didn't have this issue prior to the LCD swap.             Hang on, this is the first we have heard of an LCD swap.   Did you get the new LCD from Roland, and/or is it a part that it known to work properly in this keyboard?   I smell a Red Herring.       Gareth.

bitrex <bitrex@de.lete.earthlink.net>: May 01 02:58PM -0400 > And, of course, it could be two-or-more things if you, in fact, bridged something replacing a resistor.   > Peter Wieck > Melrose Park, PA   Cool! The dental-spade trick seems to have found a candidate (I used a tiny tiny phillips head screwdriver for manipulating each wire on the header individually.)   Purple wire. When I wiggle that one around the keypad becomes responsive. The others have no effect.   I did some reading and I think the reason the keyboard and the sound engine is behaving goofy is because I swapped the RAM backup battery, and it's become corrupted. The processor has no internal memory, and uses the external battery-backed RAM for both its heap/stack and storing patch data.   There's a startup key combination that instructs the processor to wipe the memory and re-initialize, but of course I can't execute it when the membrane buttons aren't working...: )

"Gareth Magennis" <soundserviceleeds@outlook.com>: May 01 08:08PM +0100 "Jeff Liebermann" wrote in message news:mhgcibpgtjil6napgqkc2uvdjagt1svio8@4ax.com...   On Sun, 1 May 2016 13:47:13 -0400, bitrex   >I think the problem may not be mechanical, as I've noticed that now the >keyboard is having issues triggering as well, which is not connected to >the same area.   Well, it wouldn't hurt to eliminate the keyboard as a possibility. Put an ohmmeter across a row and column on the keyboard and measure the contact resistance with an ohmmeter. Try all the button combinations. If the resistance seems resonable, move on to looking for another culprit.   >I think I screwed something up swapping R66 on page 18 near the LCD, and >the processor is having trouble with read/writes or something.   5.6K goes to Vo on the LCD display, whatever that does. If it's carbon comp, check the resistance with an ohmmeter. They change over time and absorb moisture. However R66 doesn't seem to go anywhere except the display making changes to keyboard and buttons rather unlikely. Dunno.                 R66 is most likely contrast or viewing angle adjustment. It might be a good idea to check all the pullup resistors (RA3) are all present and correct.   It is probably another good idea to just resolder everything around that part of the circuitry, including the Gate Array, just to eliminate dry joints as the problem. That's a 5 minute job at most.   And, if you (the OP) have replaced R66, go look at it again with a loupe or magnifying glass and check you haven't inadvertently shorted something out, or there is maybe some solder debris sitting on the Gate Array pins.       Gareth.       Gareth.

"Gareth Magennis" <soundserviceleeds@outlook.com>: May 01 08:20PM +0100 "bitrex" wrote in message news:QlsVy.14079$tt5.2388@fx34.iad...   > something replacing a resistor.   > Peter Wieck > Melrose Park, PA   Cool! The dental-spade trick seems to have found a candidate (I used a tiny tiny phillips head screwdriver for manipulating each wire on the header individually.)   Purple wire. When I wiggle that one around the keypad becomes responsive. The others have no effect.   I did some reading and I think the reason the keyboard and the sound engine is behaving goofy is because I swapped the RAM backup battery, and it's become corrupted. The processor has no internal memory, and uses the external battery-backed RAM for both its heap/stack and storing patch data.   There's a startup key combination that instructs the processor to wipe the memory and re-initialize, but of course I can't execute it when the membrane buttons aren't working...: )             Here's what I put in my Service Report on an Alpha Juno 2 I repaired January this year:   "Check Battery. Reinitialise RAM. Replace Power Supply capacitor. Resolder all joints on Power Supply PCB. Clean all key contacts and contact PCB"       The system here was corrupted, though the battery was good. You need to do the reinitialise procedure. And have a good look at the Power supply too.       Gareth.

bitrex <bitrex@de.lete.earthlink.net>: May 01 03:29PM -0400 On 05/01/2016 03:20 PM, Gareth Magennis wrote: > do the reinitialise procedure. > And have a good look at the Power supply too.   > Gareth.   Thanks! All power supply filter caps have been replaced with fresh Nichicons; one of them looked like it was starting to get the plague. All the voltages are within tolerances and the HV inverter is putting out around ~90 VAC.   All the keys were removed and the membrane contacts were cleaned. That was a pain in the ass job.

"Gareth Magennis" <soundserviceleeds@outlook.com>: May 01 08:43PM +0100 "bitrex" wrote in message news:WOsVy.43993$1Q2.18402@fx33.iad...   On 05/01/2016 03:20 PM, Gareth Magennis wrote: > do the reinitialise procedure. > And have a good look at the Power supply too.   > Gareth.   Thanks! All power supply filter caps have been replaced with fresh Nichicons; one of them looked like it was starting to get the plague. All the voltages are within tolerances and the HV inverter is putting out around ~90 VAC.   All the keys were removed and the membrane contacts were cleaned. That was a pain in the ass job.             OK, so it looks like these are the common ailments of the Alpha Juno 2!   Gareth.

bitrex <bitrex@de.lete.earthlink.net>: May 01 03:58PM -0400 On 05/01/2016 03:43 PM, Gareth Magennis wrote:   > OK, so it looks like these are the common ailments of the Alpha Juno 2!   > Gareth.   Apparently both the EL backlight and the inverter are prone to failure. The inverter looks like a pretty simple blocking oscillator configuration, either the filter cap or transistor can fail. If the transformer fails then you're probably SOL.   The EL material fades out over time.   The inverter on mine was putting out good HV as is, but the EL material had faded. I happened to have some EL material lying around so I fitted that, but in the process the old LCD display basically crumbled as I removed it. Fortunately I found an unlit display module that was pretty much an exact replacement on eBay - 3 for $3. I just had to scrape off the reflective backing. The contrast resistor needed adjustment though.   Some people disconnect the inverter and just replace it with a standard 16x1 LED display, fed from the +5 rail, that mod is apparently drop-in. A few people have replaced their AJ screens with OLED displays, but they aren't 100% compatible and need a hacked firmware ROM to support them.

"Gareth Magennis" <soundserviceleeds@outlook.com>: May 01 11:21PM +0100 "bitrex" wrote in message news:7etVy.15605$u52.14969@fx13.iad...   On 05/01/2016 03:43 PM, Gareth Magennis wrote:   > OK, so it looks like these are the common ailments of the Alpha Juno 2!   > Gareth.   Apparently both the EL backlight and the inverter are prone to failure. The inverter looks like a pretty simple blocking oscillator configuration, either the filter cap or transistor can fail. If the transformer fails then you're probably SOL.   The EL material fades out over time.   The inverter on mine was putting out good HV as is, but the EL material had faded. I happened to have some EL material lying around so I fitted that, but in the process the old LCD display basically crumbled as I removed it. Fortunately I found an unlit display module that was pretty much an exact replacement on eBay - 3 for $3. I just had to scrape off the reflective backing. The contrast resistor needed adjustment though.   Some people disconnect the inverter and just replace it with a standard 16x1 LED display, fed from the +5 rail, that mod is apparently drop-in. A few people have replaced their AJ screens with OLED displays, but they aren't 100% compatible and need a hacked firmware ROM to support them.                 Yes, I recently replaced the LCD on a Juno G, which was no longer available. I got the updated LCD from Roland, complete with firmware upgrade, that would enable the Juno to properly talk to the new LCD.         Gareth.

"Gareth Magennis" <soundserviceleeds@outlook.com>: May 01 11:44PM +0100 Yes, I recently replaced the LCD on a Juno G, which was no longer available. I got the updated LCD from Roland, complete with firmware upgrade, that would enable the Juno to properly talk to the new LCD.               Oh, and after supplying the serial number of this Juno G, Roland supplied the new LCD and firmware update for free.   The customer was delighted, as was I, even though I made no profit on the parts.   It was an uneconomical to repair, otherwise.         Gareth.

bitrex <bitrex@de.lete.earthlink.net>: May 02 06:49AM -0400 > And, of course, it could be two-or-more things if you, in fact, bridged something replacing a resistor.   > Peter Wieck > Melrose Park, PA   Question is now that I've located the problem, what's the most effective way to make an expedient repair? I can't seem to get the wire to make firm contact no matter how I poke at it, and it seems impossible to pull out of the header.   I'm thinking about just clipping it off, heat shrinking a longer section to it and then soldering it directly to the underside of the board, but that seems a bit barbaric.

"pfjw@aol.com" <pfjw@aol.com>: May 02 04:01AM -0700 On Monday, May 2, 2016 at 6:49:30 AM UTC-4, bitrex wrote:     > I'm thinking about just clipping it off, heat shrinking a longer section > to it and then soldering it directly to the underside of the board, but > that seems a bit barbaric.   The solution that I use for this issue, typically, is to strip a small piece of fine gauge (appropriate to the MPC) copper wire -leave it on the spool for leverage - preferably hardened, and I keep a couple of small spools _only_ for this purpose, and push it down the connector beside the broken wire. Touch this wire with a hot iron and a bit of solder to bridge the break, and then cut it off with fine nippers. If the MPC is very fine, I will pre-tin the wire as it may not flow down the hole. If and then, a bit of hot-melt or similar to insulate any exposed wire. Done.   I have been known to use a silver-plated sewing needle, broken off to the proper length if copper would be too soft. They solder very nicely.   Peter Wieck Melrose Park, PA

Phil Allison <pallison49@gmail.com>: May 01 07:01PM -0700 > > I thought that gold was tricky to solder precisely because it did tend > > to dissolve unless the solder was already loaded with gold.   > Not really. Gold is also somewhat lubricious - and things flow well on it. BUT, they do not STICK well to it. Solder will flow and appear to be nice and tight, until it peels off like cheap tape. But it takes more than heat to cause gold to dissolve.     ** In fact gold dissolves readily in tin and hence solder.   Normally, gold plated parts have a nickel underlay which does not readily dissolve to form an alloy with solder. This results in joints that have poor mechanical strength.   https://en.wikipedia.org/wiki/Gold_plating#Soldering_issues   http://www.indium.com/blog/intermetallics-in-soldering.php     .... Phil

Danny DiAmico <dannydiamico@yahoo.com>: May 01 11:40PM Thanks for all your advice; I think it's the Motor Control Unit (Whirlpool P/N 8540540).   If you skip to the bottom of this post, you'll see pictures of the burned board. Do you concur based on the photos below that it's the motor control board?   Why didn't the diagnostic test work then?   Anyway, after being totally unsuccessful at getting the Whirlpool duet sport WFW8410SW washing machine to diagnose anything other than F28 (which is apparently the same "communications error" as the infamous F11 that youtubers all deplore), I finally just took the whole thing apart.   The en133200 F11.126/980-214 EMI Noise Filter near where the power comes in seemed to be in good shape: http://i.cubeupload.com/9NouUy.gif   The main computer control board (Whirlpool PN W10063510) also seemed to be in good shape on the bottom: http://i.cubeupload.com/3AJpZe.gif   And on the top: http://i.cubeupload.com/vHyNQx.gif   And even looking to the sides: http://i.cubeupload.com/s47l8r.gif http://i.cubeupload.com/HXFRaC.gif   But, the motor control board had "something" wrong with it based on what the plastic looked like: http://i.cubeupload.com/0hFNfc.gif   I don't know what actually burned yet: http://i.cubeupload.com/NzBAH1.gif   As the two capacitors seem to be intact: http://i.cubeupload.com/DLgrxP.gif   Here's one of the capacitors at a side view: http://i.cubeupload.com/LHKttV.gif   And here's the other capacitor: http://i.cubeupload.com/eySoyP.gif   This shows a burned trace on the MMU: http://i.cubeupload.com/zTTwBd.gif   And this shows a closeup of that: http://i.cubeupload.com/pg2KkN.gif   As does this show burnt components or traces: http://i.cubeupload.com/hXFq4P.gif   I don't think I can figure out, on my own, whether it's repairable (I suspect it's not - do you?).   So, at this point, if you have good pointers for where to buy a new Whirlpool motor control board (PN 8540540), I'd appreciate more advice now that it's pretty sure that it's the MCU and not the CCU.

Danny DiAmico <dannydiamico@yahoo.com>: May 02 12:17AM On Sun, 01 May 2016 23:40:24 +0000, Danny DiAmico wrote:   > Thanks for all your advice; I think it's the Motor Control Unit > (Whirlpool P/N 8540540).   The part number seems to be either 8540540 or AKO 706497-05 based on this sticker on the Whirlpool WFW8410SW motor control board. http://i.cubeupload.com/H3k19q.gif   I wonder what caused the board to blow up? Notice this capacitor has a hole blown in it, for example: http://i.cubeupload.com/UQQp1S.gif   Do you think if I put in a new board, that it will also blow?

ohger1s@gmail.com: May 01 12:41PM -0700 I have an old IBM labelled Fluke built DMM (8060a equivalent) that hasn't worked in years for reasons I don't recall exactly, but seem to think it was stone dead. I had it apart and left in a box and, since my last 87 crapped out a few weeks ago, I needed the low ohms feature of one or the other so I took another look at the old IBM.   I found just about every electrolytic on the board physically leaky, and most down in value and ESR, some considerably. I replaced them all but when assembling the meter, I checked the two flexible rubber interconnect strips. One of them is round and reads zero ohms all across it's length, so that one's good.   The other is a flat rectangular piece, and I cannot get any kind of resistance reading *anywhere* across it. I've cleaned it several times including using an abrasive last time and cannot get a whiff of conductance, and I've put considerable pressure on the test leads. I guess it being unassembled and sitting in free air must have poisoned it somehow as I don't recall it having any issues with erratic segments before the meter died.   It will be easy to hard wire this but was wondering if this is a low ohm transfer strip of something maybe a few ohms to a few thousand. If it's low ohms, I'll just hard wire it. If it's something other, there's plenty of room to put in 1/8 w resistors of appropriate value.   Anyone know the approximate resistance of the strip?

"pfjw@aol.com" <pfjw@aol.com>: May 01 01:17PM -0700 > Anyone know the approximate resistance of the strip?   It would not be in the best interest of any (legitimate) manufacturer to build a precision-resistance into an interconnect strip. As you have discovered, they can be volatile, and any actual planned resistance will necessarily generate heat - leading to even quicker failure.   Hardwire it - and if it works properly (and it should if this is the only problem), you are done.   Peter Wieck Melrose Park, PA

ohger1s@gmail.com: May 01 02:00PM -0700 > Hardwire it - and if it works properly (and it should if this is the only problem), you are done.   > Peter Wieck > Melrose Park, PA   Thanks Peter. I don't think any resistance (assuming there is any) would be a problem. The strip in question feeds the LCD display glass and the draw would likely be few micro amps at 5V. I was thinking in terms of the conductive pads used to active scan lines in cheap keyboards. Those measure from a few dozen ohms to a few K ohms and work properly.   In any case, I'll take your advice and hard wire it when I get to work tomorrow and see what happens.   John

all2001@spambog.com (Wolfgang Allinger): May 01 05:04PM -0300 On 01 May 16 at group /sci/electronics/repair in article 1ec60e64-b347-4d72-8754-44536d9bd8ad@googlegroups.com >If it's low ohms, I'll just hard wire it. If it's something other, >there's plenty of room to put in 1/8 w resistors of appropriate value.   >Anyone know the approximate resistance of the strip?   see http://mrmodemhead.com/blog/fluke-8060a-repair/   with the answer from Jack on August 18,2014 near the end       Saludos (an alle Vernünftigen, Rest sh. sig) Wolfgang   -- Wolfgang Allinger, anerkannter Trollallergiker :) reply Adresse gesetzt! Ich diskutiere zukünftig weniger mit Idioten, denn sie ziehen mich auf ihr Niveau herunter und schlagen mich dort mit ihrer Erfahrung! :p (lt. alter usenet Weisheit) iPod, iPhone, iPad, iTunes, iRak, iDiot

Jeff Liebermann <jeffl@cruzio.com>: May 01 02:53PM -0700 >Anyone know the approximate resistance of the strip?   Some photos of the insides of an 8024a, which is fairly close in construction to an 8060a. <http://www.eevblog.com/forum/testgear/fluke-8024b-33-years-old-and-still-going-strong!-beware-3mb-photos/> The ribbon cable: <http://s193.photobucket.com/user/Bl4ckW0lfi3/media/Fluke8024B-09_zps4b433951.jpg.html> The ribbon cable between the two boards is made from screened graphite, which tends to crack if flexed. I found a similar ribbon cable, but made from flattened copper wire that looked more reliable. I removed the original ribbon cable, clamped in the new cable, and after a bit of jiggling, got it to make a connection without soldering. Once it was working, I used hot melt glue to hold it in place. I suppose soldering would have been easier, but at the time, I didn't want to wreck the meter.       -- 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

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.