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Chemi-con Capacitors - Any Good? Utility Plugins
Old 27th August 2008
  #1
Gear Maniac
 

Chemi-con Capacitors - Any Good?

I just opened up my Tascam M-3500 to check out the innards. I'm trying to identify the manufacturer of the capacitors. I'm wondering if this console has already been recapped at some time in the recent past.

The electrolytics are dark blue with a light silvery-blue stripe. They look very much like the Panasonics I've seen pictures of on the web. They're definately not Nichicon, as the name is not running vertical down the side. One of the larger ones says "SME" horizontally near the top, the others don't seem to have any manufacturer's ID. The value markings run horizontal, and the one picture I saw of a Panasonic had the values running vertical.

As soon as we can post photos, I'll post one. If they are Chemi-con brand, are they any good, as compared to the (Jim Williams recommended)Panasonic FM series?

Thanks.
Bill Knipe

Last edited by GorillaToast; 27th August 2008 at 09:40 PM.. Reason: to correct name of item
Old 28th August 2008
  #2
Gear Maniac
 
Gzmo's Avatar
 

Hi there.
im in a huge recap project so maybe I can help U.
Im using capxcon,nichicon,rubycon (low esr audio tested) capacitors.
These are the solution for you as well I guess...
The Panasonic is good too but keep it in mind the low running hours.Thats why im using those.
all my best
RoB
Old 28th August 2008
  #3
Gear Maniac
 

Thanks RoB,

I guess what I'm really trying to determine is whether or not definately need to recap or not at this point in time. I'n not getting any clicks or pops out of the console, and it's my understanding that this is a sure sign of needing a recap. I've read that it's probably wise to do it anyway on a board this old, but as its a huge undertaking, and this is low-end board to begin with, I'm notsure it's necessary for me right now.

I'm hoping someone with knowledge of Tascam consoles will be able to tell me if the United Chemi-con caps are OEM or not.

Thanks.
Old 29th August 2008
  #4
I can't personally remember, but they are generic 85 degree caps, and too small at that. Use 220 uf/25 volt Rubycon ZL, Nichicon HE or Panasonic FM. All are the new super low impedance tantalum substitutes. All are rated at several thousand hours at rated temperature (125 degrees), at 70 degrees they should last 30~40 years. Use 100 uf/50v to replace the 10uf mic pre input caps. Buss feed caps should be 470 uf for a deep, tight low end. Bypass with quality film caps to retain air.

Jim Williams
Audio Upgrades
Old 30th August 2008
  #5
Gear Maniac
 

Thanks Jim. I'll report back how it sounds after the mods are done. Will I need to upgrade the power supply also?

Last edited by GorillaToast; 30th August 2008 at 03:15 AM.. Reason: fix typo
Old 30th August 2008
  #6
It wouldn't hurt. I find that the caps are now much smaller which allows you to replace the large units with caps of greater value. The 105 degree models are also recommended.

Jim Williams
Audio Upgrades
Old 30th August 2008
  #7
Gear Maniac
 

Quote:
It wouldn't hurt. I find that the caps are now much smaller which allows you to replace the large units with caps of greater value. The 105 degree models are also recommended.
Jim, would that be the ones in the external PSU? I haven't opened it up yet to see what's inside. I still haven't ordered the schematics from Tascam yet (next week), so I'm not sure which caps are the buss feed caps and which are the bypass caps.

when you say to use 220uf/25v caps, what are they replacing? The ones in the EQ circuit, or any that aren't either the 10uf input couplers, or the buss feed caps?

Thanks again for all your help.

Side Note: How long should I leave the PSU unplugged to ensure that the caps have completly drained?

Bill
Old 1st September 2008
  #8
Lives for gear
 

a electrolytic cap is a cap and in some circuits it doesn't matter. in other circuits hand picking them to match across a couple a channels seems to work even better.

xicon is relabled rubycon/nicon as they are not really a manufacture as more as a domestic reseller under the Mouser co.

even though capacitors sometimes are nessecary evils, I try to not to use so many of them in my electronics I create.

united chemical caps are just regular caps, but they do make industrial/medical grade/quality caps. If my memory serves me right, SME is the low impedence series of thier caps (united chem-con)
Old 1st September 2008
  #9
Gear Maniac
 

Quote:
Originally Posted by drtechno View Post
a electrolytic cap is a cap and in some circuits it doesn't matter. in other circuits hand picking them to match across a couple a channels seems to work even better.
Does that mean, "yes" I should just replace ALL the electrolytics with 220uf ones, despite what the circuit designer specified? I always asumed that changing the values of the components in a circuit would cause it to either not work, or blow up.
Old 2nd September 2008
  #10
No, impedance considerations are important. There is no need for a 220 uf cap to couple into a 100k input impedance, typical for a fader amp. Outputs are where the larger units are placed. The 2x3.14/RC formula will tell you where input roll offs occur. One benefit of replacing all of them is reliability. The long life low impedance 105 degree caps will last 30 years, maybe more. I would change all of them just to avoid any problems down the road. Get some tech help if you are unsure of what values to sub.

Jim Williams
Audio Upgrades
Old 4th September 2008
  #11
Here for the gear
 

General Capacitor Thoery...

I'm very interested in the response to this also. What is the overall effect of a capacitor on the sound going through it? you mentioned "Buss feed caps should be 470 uf for a deep, tight low end." I'm sure that value is specific to the circuit but is there a 'guideline' for replacing old caps with new modern ones?
Thanks
Jeremy
Old 4th September 2008
  #12
The larger values of caps need to be used where the impedance they feed is low. That includes outputs which may feed 600 ohm input transformer coupled equipment but also the buss feeds. Each buss resistor (10k in the case of the 3500) is a load on the cap. One is not a problem, but several are as the parallel resistance of all those buss resistors drops the load far below 10k ohms. In large consoles with 24 busses, most are designed with back grounded buss resistors, they are always assigned to either the buss or back grounded to ground to control capacitive crosstalk. Parallel 24 10 k resistors and that load is low impedance. The 470 uf caps prevent the low frequency roll off you incure when driving the low impedance load.


Jim Williams
Audio Upgrades
Old 4th September 2008
  #13
Lives for gear
 
ulysses's Avatar
The printing on the plastic sleeve isn't what determines a capacitor's quality. The brand name shouldn't be your primary consideration. Many different manufacturers produce a wide variety of capacitors. Look at the specs, not the name.
Here's a prioritized list of what to look for in an electrolytic capacitor:
1. Voltage rating. If it's lower than the voltage it will see, it will die.
2. Physical size. If it doesn't fit in the space available, it does you no good.
3. Leas spacing. If you can't solder it to the board, same problem.
4. Temperature and endurance ratings. Caps are rated to meet spec after a certain number of hours at a certain temp. Run them at lower than the rated temp, and they last longer. High temp caps (105C and up) will last longer than 85C caps.
5. Impedance. Premium caps are generally described as "low impedance" in the data sheets and cattle-logs. You can look at the specs for ESR, , Impedance, and "tan ∂" to compare the performance of otherwise similar caps. The idea is that the best caps are the ones that come closest to an ideal capacitor, which has continuously declining impedance as frequency increases. Of course, even the best capacitors have a point where other factors cause their HF impedance to be higher than ideal.
6. Capacitance. Modern caps are more compact and space-efficient than the older stuff they replace. In many cases, the coupling and decoupling caps in older gear are smaller that would have been preferred, due to space and cost considerations. Recapping is an opportunity to evaluate the circuit and see if more capacitance would offer an advantage. Of course there are instances where increasing the capacitance would be a bad thing. These are relatively rare though: Electrolytics generally have wide tolerances, so they're not likely to be used in frequency-critical applications.
7. Price. There's wisdom in appreciating the point of diminishing returns. Not every capacitor NEEDS to be the best possible part. If your power supply is totally hum-free, low impedance, and has plenty of current capacity to handle every signal it will see, then "upgrading" the caps would be a waste of time and money. When it comes to the coupling caps, you'll find there's more to be gained by eliminating the need for them rather than trying to find the best possible capacitor. Of course that applies more to design than maintenance.
Old 7th September 2008
  #14
Gear Nut
 

Bill,

I just got got one of these boards and I was wondering what kind of mods you have done or maybe planning? I have seen some star grounding, opamp replacement and of couse replacing caps. I would love to find a good way to do the balanced out's for this board.

Dave
Old 7th September 2008
  #15
Gear Maniac
 

Dave,

The only thing I've done so far is replace the opamps in one of the modules with LM4562's, and a second module with OPA2132's. I wasn't blown away by either one, but then again I'm no expert either. There were slight differences between them and the originals... a bit more openess and a little tighter bass with the 2132's, about a 3db gain boost with the 4562's. All in all, nothing to throw a party about. But then, I haven't done the recapping yet.

I'm still undecided about doing the mods at all. After all, I only spent $800 for the board, and I got it mainly for the monitoring capabilities.

AFA the grounding, I got lucky and this board is very quiet. No hum problems at all. And I'm in a 70 yr old house with original wiring.

I've thought about the -10/ +4 thing, and since my converters are older MOTUs at -10db I'm not going to do anything about it just now. there is a DIY line leveler project on the web someplace and I thought about building 24 of them and putting them in the empty space that houses the automation module in the M-3700, but I'm not real thrilled with doing a lot of soldering. That's probably why I haven't tackled the caps yet.

good luck with your project. Looking forward to hearing how it turns out.

Bill
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