Hi guys,
I found some yellowish deposits one some Mica capacitors and trying to identify them in case they need replacement.
Does anyone know how these long 5-legs Mica capacitors are called (photo).
In the service manual (it is a Sony boombox) the description is this:
1-107-253-00 (Sony part number), - (15+18+22+27)p 500V Mica.
I have also attached a picture of the board diagram and circled those capacitors in RED ink.
I found some yellowish deposits one some Mica capacitors and trying to identify them in case they need replacement.
Does anyone know how these long 5-legs Mica capacitors are called (photo).
In the service manual (it is a Sony boombox) the description is this:
1-107-253-00 (Sony part number), - (15+18+22+27)p 500V Mica.
I have also attached a picture of the board diagram and circled those capacitors in RED ink.
Looks like on these 5-pin "array" caps, pin 5 is common for all 4 "capacitors".
Not sure how could I match that configuration with 4 separate caps.
Any help?
Not sure how could I match that configuration with 4 separate caps.
Any help?
Make a small circuit board (vertical orientation) with the appropriate size, pattern, and leads.
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That sort of cap array rarely fails, and most likely it does not need replacement.
That yellow stuff looks to be from another source, not those capacitors.
There's nothing like that inside them. Perhaps an old electrolytic capacitor
in the unit exploded at some point and sprayed gunk around inside.
There's nothing like that inside them. Perhaps an old electrolytic capacitor
in the unit exploded at some point and sprayed gunk around inside.
I am fairly sure they yellow deposits you see is adhesive they used to keep some parts from rattling. Not likely a problem with the capacitors.
You would need to re alibrate the bias section if you replaced them.
You would need to re alibrate the bias section if you replaced them.
The caps in there are most likely ceramic, maybe X7R or even NPO, in those small values. Unless the array was severely beaten up with overvoltage, I'd say those caps are likely good. If anything were wrong with the array, it would likely be a bad internal connection.
Hi guys,
thank you for all your responses.
I haven't identified any issue with those caps, I was just alarmed by the yellow deposits almost all of them were covered with.
But as daqvin_carter and rayma noted, that must be either adhesive or, at least, not something coming from those particular Mica caps.
I'd better leave those alone.
Thank you!
thank you for all your responses.
I haven't identified any issue with those caps, I was just alarmed by the yellow deposits almost all of them were covered with.
But as daqvin_carter and rayma noted, that must be either adhesive or, at least, not something coming from those particular Mica caps.
I'd better leave those alone.
Thank you!
Yes.
Maybe there was a candle sitting on top of the amp, and wax leaked down into the chassis.
Try scraping some off, and see if it's wax.
Maybe there was a candle sitting on top of the amp, and wax leaked down into the chassis.
Try scraping some off, and see if it's wax.
Take a small piece out, and keep on a tile, or metal.
Touch it with a hot soldering iron.
Might be hot melt glue, you will know by the small.
If it smells nasty, remove the board and give it a good wash, the stuff might be corrosive.
Touch it with a hot soldering iron.
Might be hot melt glue, you will know by the small.
If it smells nasty, remove the board and give it a good wash, the stuff might be corrosive.
The coating on the cap array is a baked-on material that is not moisture proof, so the arrays were dipped in wax to provide that protection. One brand of that was called Durez, and it was made by a long ago defunct company called Centralab.
In the old days, these were often called Printed or Packaged Electronic Components or PECs.
https://thedhtsstore.com/blogs/news/35901185-vintage-components-the-pec-a-k-a-couplate-or-bulplate
Among other applications, they were often used in electronic organs where the manufacturer needed the same circuit reproduced over and over (to generate tones, for example). Instead of stuffing circuit boards with discrete components, they could save time by mounting these prepared modules on rows of PCB holes. But because they were specialized to a particular product, they were never, as far as I know, generic components.
https://thedhtsstore.com/blogs/news/35901185-vintage-components-the-pec-a-k-a-couplate-or-bulplate
Among other applications, they were often used in electronic organs where the manufacturer needed the same circuit reproduced over and over (to generate tones, for example). Instead of stuffing circuit boards with discrete components, they could save time by mounting these prepared modules on rows of PCB holes. But because they were specialized to a particular product, they were never, as far as I know, generic components.
It is wax used to dip the capacitors in. The brown material is also quite weak. Never trusted caps when they were "exhaling" the wax in time so I replaced them if the equipment was worth it. They do exhibit the same behavior when soldered. You could measure a few of them and see if they are still accurate. If so they can stay. I have some doubt that they are mica caps as I know these as ceramic caps but since I don't work on old stuff anymore I might be wrong. There was a habit calling parts with a wrong description at Sony. For example teflon caps that were simple mylar caps.
The old carbon potentiometers as in the picture often make bad contact in time, especially in moist environments.
The old carbon potentiometers as in the picture often make bad contact in time, especially in moist environments.
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You can test those cap arrays with a scope.
Ste the boom box to record with no audio input and scope the record head.
The signal level should be the same for both channels on each tape type/formulation setting.
That glue is often corrosive after it has aged for a few years. It is usually not a problem on the resin dip part of the component.
Failures happen if it is on power resistors or on the boundary between the component lead and the paint/dip.
I have seen the stuff corrode its way right through a hook-up wire link in the past.
Ste the boom box to record with no audio input and scope the record head.
The signal level should be the same for both channels on each tape type/formulation setting.
That glue is often corrosive after it has aged for a few years. It is usually not a problem on the resin dip part of the component.
Failures happen if it is on power resistors or on the boundary between the component lead and the paint/dip.
I have seen the stuff corrode its way right through a hook-up wire link in the past.
That glue you mention is the type used to glue electrolytic cap with?!?! It may be that stuff but it can also be the wax old capacitors are dipped in. That specific glue is terrible stuff when it ages indeed. It was used mostly on large parts to prevent them coming loose from the then brittle Pertinax PCB's (and protecting the PCB's from cracking at the same time).
IF that glue is used it will certainly be at the large filter caps. If it is the wax then often very small mold like spots can be noticed at those brown capacitors.
IF that glue is used it will certainly be at the large filter caps. If it is the wax then often very small mold like spots can be noticed at those brown capacitors.
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I worked for a company in WI called Centralab, and they made custom circuits using those encapsulated modules. The brown baked-on coating was called Durez. There was also a black Durez as well. Some modules were wax-impregnated; others were not. Centralab got bought by North American Philips (NAP), and NAP sold the company to an independent intrapreneur who renamed it MMC (Microelectronic Modules Corp.). That went belly up and the remains (customer base, antiquated equipment, and patent rights & other intellectual property) got bought by Bourns, Inc in CA. I moved to CA to finish my working life there & retired.
I'm going to re-open the boombox the following days as I need to do some work with the REC/PB head (might replace it if the factory one keeps misbehaving
in the high frequencies) and I will then check those caps although I don't believe there is a problem with them.
Those old carbon potentiometers have been measured already and all of them checkout OK.
I had issues with the REC/PB switch which I was lucky enough to find a NOS replacement and I have replaced it already. The issue was it was causing
a very loud high frequency distortion noise on the right channel every time the cassette PLAY button was pressed. It was impossible not only to listen
to the music program of the cassette but also to make an alignment/adjustments of the head/playback section because that HF noise was dominating the inputs of my oscilloscope and could not get any decent readings.
Had a number of other issues with this boombox when I got it, it had a failed fuse (so it was not turning on at all) and I thought that replacing the fuse would fix it.
New fuse inside and then power on -> poof the new fuse was gone. Turned out the (Sony proprietary) transformer was bad. Took me some time to find
a modern transformer to match it and replace it, had to modify the connections of the voltage selection board as well (the stock transformer supported 4 different voltages of 110v, 120V, 220V, 240V, I replaced the transformer with one which supports either 115V or 230V - oh well, that would work in most countries as I believe a deviation of 5V at 115 or 10V at 230 is not something the xformer would not handle).
FM Tuner would not tune in Stereo for known "Stereo" stations, thankfully I managed to fix that too.
It's all fun. It's the hardest repair I ever attempted as a hobbyist and it's been over a month already I'm dealing with this boombox 😀
...but I'm close to complete everything that needs to be done on it...
in the high frequencies) and I will then check those caps although I don't believe there is a problem with them.
Those old carbon potentiometers have been measured already and all of them checkout OK.
I had issues with the REC/PB switch which I was lucky enough to find a NOS replacement and I have replaced it already. The issue was it was causing
a very loud high frequency distortion noise on the right channel every time the cassette PLAY button was pressed. It was impossible not only to listen
to the music program of the cassette but also to make an alignment/adjustments of the head/playback section because that HF noise was dominating the inputs of my oscilloscope and could not get any decent readings.
Had a number of other issues with this boombox when I got it, it had a failed fuse (so it was not turning on at all) and I thought that replacing the fuse would fix it.
New fuse inside and then power on -> poof the new fuse was gone. Turned out the (Sony proprietary) transformer was bad. Took me some time to find
a modern transformer to match it and replace it, had to modify the connections of the voltage selection board as well (the stock transformer supported 4 different voltages of 110v, 120V, 220V, 240V, I replaced the transformer with one which supports either 115V or 230V - oh well, that would work in most countries as I believe a deviation of 5V at 115 or 10V at 230 is not something the xformer would not handle).
FM Tuner would not tune in Stereo for known "Stereo" stations, thankfully I managed to fix that too.
It's all fun. It's the hardest repair I ever attempted as a hobbyist and it's been over a month already I'm dealing with this boombox 😀
...but I'm close to complete everything that needs to be done on it...