Soundtracs Solitaire Cap replacement

[Joey777]

Hi folks, I am thankful to be here with such knowledgeable people.
I have a question. My Soundtracs Solitaire has dropped a few channels. I took the boards out and gave them a clean and done my best ( with little experience ) to look for bad solder joints and wear on the capacitors. I have spotted some worn looking caps and would like to replace them. When ordering caps I seen there are both ac and dc caps for sale. I am not sure what to buy and it's proving difficult here in the Netherlands to find caps@ 6.3V 100micro farrads.
Could you folks help with what type ac or dc and a good make to buy.
And the 6.3V 100 micro farad, is this common or maybe old and obsolete. I have no idea.

Would love to get my beloved console back up and running.

Thanks for any help

Edit: The capacitors are Axial type mostly.

 

[Ike Zimbel]

Any 100uf cap that is equal to or greater than 6.3v rating will work. 100uf/10v would be the next closest value but 16v or 25v will work, too. At some point, the physical size of the cap will become too large with a higher voltage rating, so a 100uf/63v cap would work, circuit wise, but it might be too big to fit in the space allotted. You can also use radial caps instead, as long as you insulate the leads so they don't short against any circuit board traces they pass over. Note that some circuit boards were actually laid out to fit either type of cap, but I have no idea if yours would be like that. Pictures would help.
Make sure to take note of the orientation of the caps so you can maintain the proper polarity. If this is marked on the board, as it usually is, it is worth double checking that the part is in with the + end at the + marking on the board. Over the years, I have seen different boards where the artwork was incorrect and the part needed to be fitted the opposite way from what is marked on the board. Your only chance of catching this error is by carefully noting how the existing part is fitted. Taking pictures is also a good way to have something to reference, as is checking the same part on another module.

 

[Joey777]

Thanks very much for your reply. Your a star. I took a few fotos.
Some great advice there. I will take fotos to remember the orientation. Should I rig up a discharge resistor before removong the caps. I have seen some videos where folks are bridging the contacts with pliers and what-not. What would you suggest to do.
Are the caps AC or DC.
Thanks again for all your help.
Sorry for the bombardment of questions

 

[abbey road d enfer]

The Solitaire has been launched in about 1994-95. Since then , electrolytic caps technology has improved, not as significantly as in the 20 years preceding, but still it allows improving performance by permitting to use higher nominal value, voltage and temperature rating in the same size package as the ones they replace.
For example, a 100uF/25V could be replaced with a 220uF/35V with a 105°C rating. Using a higher nominal value results in better LF distortion, whilst using 105°C improves reliability.

 

[Joey777]

Thank you very much for your reply abbeyroad. Theres alot to take in for me and the 2 posts above are fantastic. I didn't even think that replacing the caps would improve the signal or with new caps and the modern design of the caps would improve the future reliability of the desk. You guys and girls rock, for sure.
I just have 2 more questions then I will leave you in peace.
Are the caps AC or DC.
What would be a good way to discharge the caps before replacing them.

Thanks ever so much for all your help

 

[abbey road d enfer]

Thank you very much for your reply abbeyroad. Theres alot to take in for me and the 2 posts above are fantastic. I didn't even think that replacing the caps would improve the signal or with new caps and the modern design of the caps would improve the future reliability of the desk. You guys and girls rock, for sure.
I just have 2 more questions then I will leave you in peace.
Are the caps AC or DC.

The caps you need to replace are the electrolytics. Most often they are polarized (meaning there's a positive and a negative side), but sometimes a designer would spec non-polarized (NP) electrolytics. The giveaway is they don't have a polarity sign on them. I doubt Soundtracs ever used them.

What would be a good way to discharge the caps before replacing them.

You don't need to discharge caps.
This is something that's recommended for tube equipment because of teh high voltage involved, but in a mixer, all caps are discharged after a few seconds.

 

[Joey777]

Thank you very much. I noticed most of the caps have an arrow pointing one way. I will keep an eye on the orientation.
I was thinking to buy the caps from a webshop called Farnell but noticed, there's AC and DC caps, which should I get.
Thanks again

 

[Ike Zimbel]

I'm not sure where you are seeing the DC vs AC ratings on the caps you are looking for. You just need to get the voltage correct (some film caps have different ratings for AC and DC but you do NOT need to replace the film caps). I'm not clear from your original post if you are only looking for 100uf / 6.3v caps because that's the only value in your desk (which is unlikely...). Or, you have found the other values but are having trouble finding only the 100/6.3v? You need to be aware that two caps can be the same physical size, aka "package" but different values. For example, I have a 1uf/100v and a 100uf/16v cap in front of me and they are both the same size. The trade-off is between voltage rating and capacitance...more of one = less of the other in the same size package.
The reason I mention that is because in your pictures I see two caps that are clearly power supply decoupling caps (it's hard to make out the numbers but I'm going to call them "C-82" and "C-84" in the first picture) and they can NOT be 100uf/6.3v volts because they would need to have a voltage rating higher than the power supply voltages of 15-18 volts. So, they might be 22, or 47uf at 25 volts in the same size package as the 100/6.3v.
Here is a link to two 100uf axial caps at the Digi-Key Canadian site. You should be able to change countries somewhere in the top margin. Those caps are Vishay now, but once upon a time they were Phillips and made in your home country.
One final note: Unless your desk runs really hot, and has been left on for a very long time, I question whether capacitor failure is what's causing your channels to not work. If you are in over your head, consider hiring a tech before you damage your console.

 

[abbey road d enfer]

there's AC and DC caps,

Can you link some examples.
There are polarized caps and non-polarized. The polarized ones could be somehow quoted as DC caps.
I noticed an additional issue, which is that many of teh caps are axial, which tend to be more or less extinct. The choice will be restricted.

 

[Joey777]

Hi,

I am looking for these caps:
6.3v 100 axial
10v 1000 radial
25v 330 radial
25v 22 axial "515c" ??
100v 4.7 axial

The axial caps are all 4.5mm and alot of the caps are side by side not leaving alot of room to replace with larger physically sized caps.
C82 is 6.3v @ 100
C84 is 25v @ 330

I am gonna have a look on the site you linked to, thanks for that.
There used to be a Large Phillips factory in the small city close to where I live. It shut down about a few years ago when the last of the machines used to make condensers? for starting fluorescent lights and such, I think. Were moved to Poland. The last of the Dutch crew were sent over to Poland to help with the assembly and training up the Polish folks on how to use the machines. There have been many manufacturing problems since the start-up. Hopefully they have all the probs worked out.

The desk is used alot and can be left on for 12hrs + sometimes. I did get a tip that checking and or re-flowing the joints on the interconnects could help. I am getting power on all the ic's. I seen a video somewhere, where the tech was using an old headphone connected to a capacitor I think, to sniff out faults. When the signal was good / present, the headphone would bleep. That looked good. Would be nice to make something like that.

Thanks again for all your help.

Joey.

P.S. I live in the Netherlands for 20+ years but originally born in Scotland......beam me up scotty.........ah have-nae got the power captain

 

[Joey777]

Some close-ups of the caps I would like to replace, also for preventative maintenance for the caps that are ok but have lived in there since 1995. ha ha

 

[Joey777]

Thanks a million everyone for all your help

 

[musgrave]

I have had great size/performance results with solid polymer lytics for tighter spaces.

 

[Fdieck56]

Thank you very much for your reply abbeyroad. Theres alot to take in for me and the 2 posts above are fantastic. I didn't even think that replacing the caps would improve the signal or with new caps and the modern design of the caps would improve the future reliability of the desk. You guys and girls rock, for sure.
I just have 2 more questions then I will leave you in peace.
Are the caps AC or DC.
What would be a good way to discharge the caps before replacing them.

Thanks ever so much for all your help

They are DC polar electrolytics. They have a electrolytic solution in them that drys out in 15 on twenty years use a good Japanese cap like Panasonic, Elna, Nichicon, United Chemicon, Rubicon… stay away from in expensive Chinese caps. Keep the polarity correct. The arrow points to ground side on the caps. This will the side that is not marked with a plus. The cap will fail if installed in the wrong direction.

 

[Fdieck56]

The caps that are on the board now are Panasonic or Matishuta. The FC series are great and not expensive.

 

[Joey777]

Thanks very much folks. Great advice and much appreciated. I will look for the FC series. Hopefully I can get these installed and get the old girl back up and running. Would it be an idea do you think to, test the caps individually to see which caps are causing the problems? and just change the problem caps. Or since the desk is quite old, just recap the lot. There are 51 caps. Not so many for some of you but not too big of a task for me if I take my time.

Thanks folks.
Joey

 

[abbey road d enfer]

Thanks very much folks. Great advice and much appreciated. I will look for the FC series. Hopefully I can get these installed and get the old girl back up and running. Would it be an idea do you think to, test the caps individually to see which caps are causing the problems? and just change the problem caps.

Good practice is when you find one type failed, replace all of same type, because they're all gonna fail sooner or later.

Or since the desk is quite old, just recap the lot. There are 51 caps. Not so many for some of you but not too big of a task for me if I take my time.

Since it's a modular console, you can afford to undertake that in several installments.

 

[Joey777]

Thanks abbeyroad.
What would you do to sniff out the bad cap?

 

[abbey road d enfer]

That's a tricky one.
You may try a capmeter. First try in-circuit , you may or may not get a coherent indication. It may identify the component as a resistor or diode or a DeLorean 1.21 gigawatts flux capacitor. In that case, you need to lift one of the pins.
Alternatively, you may want to measure the LF response of a channel; if you see signs of loss of LF, you need to use the traditional faultfinding techniques to locate the stage(s) that cause that loss.
Some would recommend the use of an ESR meter. However, you need to be aware that capacitors made 20+ years ago gad a higher ESR than those made today.
In order to make a definitive assessment, you would need to have a brand new capacitor made with the technology of the time for comparison... Since ESR was not considered at the time as a primordial data, ESR was very seldom published in the days.

 

[Joey777]

Thanks again for your advice. I am looking for a second-hand cheap oscilloscope to buy. I would like to be able to do more fault finding and fixing up my old desk, for the future.
It does indeed sound very tricky to me. I will go slow and steady with the troubleshooting and hopefully understand more of what is going on and why. Can't remember who said that in what video. But I am going to learn more of why and how the circuits are doing what their doing and the components they use to achieve what their supposed to be doing.

I appreciate all the help. Thanks folks. Going to order the parts and go through the replacement and will post how it's going with a few pics to get some feedback, if that's ok.

Take care all and stay healthy.

Joey