identifying capacitor type

[snk]

Hello,

I would like to recap an old italian echo which is not in working order, but there is one capacitor type I can not identify : it features a grey plastic body, with slightly conic ends (red on one side, and black on the other side). It's the vertical one at the center of the picture below. The value is not visible, but I think that I should be able to see it when I desolder it.



Also, I am unsure if the ones marked with yellow arrows are either tantalum or electrolytics?


Thank you in advance !

[Rob Strand]

My *guess" is they are electros.  Mainly because of the contracted end but also because of the pedal.

Siemens and Kemet made tantalums which looks similar but they have straight side.  Also they are clearly marked with branding and logos.

[snk]

My *guess" is they are electros.  Mainly because of the contracted end but also because of the pedal.

Siemens and Kemet made tantalums which looks similar but they have straight side.  Also they are clearly marked with branding and logos.

Thank you.
This is what I thought too (them being electros), untill I found this picture, which led me to doubt about it :

because of the pedal.

This is not a pedal, it is a "desktop", quite bulky italian tape echo.

[Rob Strand]

That's a really cool unit.

Thank you.
This is what I thought too (them being electros), untill I found this picture, which led me to doubt about it :

It's hard to be 100% sure.  If I had to place bets I'd probably go as high as 90% confidence on the electros.   The styling looks like Philips but I have to admit the images aren't as clear in my head as they were 50 years ago.

You can see those tantalums have a slighty different style and construction.   There are some tantalums with contracted ends.   The large tant. in your pic is starting to edge onto an electro style but the smaller ones look like tantalums to me.

[snk]

That's a really cool unit.

It seems so :i'll tell you when it's up and running

If I had to place bets I'd probably go as high as 90% confidence on the electros.

This is what I thought first, too.
Also, the values looked like regular electros, fwiw (like 10µF 16V).

I have the schematic for the bigger brother version. It's nearly the same unit (there is a vumeter and a HP/LP tone filter on the bigger version). Unfortunately, the capacitor values are oddly labbeled (like 3K3 or 6k8 -like resistors!-, instead of 3.3µF and 6.6µF). You can check the "transistor" link on that page :
http://meazzi.org.uk/circuits.htm


And what about the big vertical grey cap with one red section (in the upper picture, circled in pink)?

[snk]

Well, I found this picture (of the second PCB from the "bigger brother version") having been recapped by someone who used electros everywhere (including the "grey & red plastic body" ones) :

(Sadly, I didn't remember the original link where I found the picture)

So i guess i'm fine going with electrolytics everywhere...?

[snk]

(these are pictures of my PCB boards).
It seems that the "big" one is the same than the one posted above (from the bigger version with more features), except for some components left out (see holes in the PCB).
The picture quality is not great, but hopefully good enough.
I'm surprised by the recapping values used in the picture above, because some are much different than the original values I can see on my board.





I hope I'll be able to put the unit back in good service, because it seems a very nice echo !

[Rob Strand]

Here's some Philips caps, looks pretty close, the only thing different is the blue (which was more common for Philips).

It seems that the "big" one is the same than the one posted above (from the bigger version with more features), except for some components left out (see holes in the PCB).
...
Well, I found this picture (of the second PCB from the "bigger brother version") having been recapped by someone who used electros everywhere (including the "grey & red plastic body" ones) :

Good find.    It going to be full of audio amp stages.   Electrolyics was the norm, especially for the era.

I have an old amplifier board from the 60's somewhere I'l see if I can dig it up.   I'm pretty sure it has some of those blue Philips caps.   There's also some silver ones but IIRC the markings were Red.  All electro's.   I dig it up tomorrow.  (I've had that thing sitting around for 50 years.)

The boards I had with axial tantalums were from the Telecom industry.  Some power supplies, some specialized stuff.   Off hand I think the axial tantalums were "solid tantalums".

[snk]

Hi,
Thank you, Rob!

Further progress : on my side, I also can confirm that the capacitors should be electrolytics : I have found another picture showing the circuit board, and on this one, the "suspicious" caps are all electrolytics.
So, I guess they used the components they hand in stock, varying slightly during the production lifespan... leading to the conclusion that I can safely use electros for all of them.

[duck_arse]

the yellowish electros look just like old Siemens electrolytics, very similar colours show in searches.

[snk]

I am comparing the values noted on my boards and the values from the recapped board picture posted above, and i am somewhat surprised by the amount of over-valued caps used in the latter.

I know that on older power supplies, it can make sense to increase voltage and capacitance ratings. Also, there are some quite odd values (like 40µF and 80µF) which will need to be swapped for 47µF and 100µF for convenience.

... But what's the point to change 40µF/16V for a 100µF/63V everywhere in a circuit board?
Is it just laziness (using less different voltage and capacitance values so you make your BoM quicker, and/or using what you already have in stock), or does it actually make sense?
As the circuit uses mostly electros, wouldn't it change the overall tone, amplification and behavior?

[anotherjim]

I'd guess the red-end cap is film and the red denotes the middle of the wrap and the outer that would be the ground end if you were worried about noise pickup.
The not blue electro's are often Facom brand in Italian stuff.

[davent]

Well, I found this picture (of the second PCB from the "bigger brother version") having been recapped by someone who used electros everywhere (including the "grey & red plastic body" ones) :

(Sadly, I didn't remember the original link where I found the picture)

So i guess i'm fine going with electrolytics everywhere...?

Lots of pictures of that recapped unit here.

https://reverb.com/item/24878323-meazzi-echomatic-1960-s-vintage-tape-delay

[snk]

Lots of pictures of that recapped unit here.
https://reverb.com/item/24878323-meazzi-echomatic-1960-s-vintage-tape-delay

Ah, yes! That's it!
Thank you

[amptramp]

The capacitor with the red end looks like a wet-slug tantalum.  Unlike the dry-slug tantalums, they could be used as power line filters.

[snk]

Interesting. I didn't even know that kind of cap existed 
Thank you for the information, Amptramp.
Could I change these with regular electrolytic caps (like someone did on the picture posted above)?

By the way, in the meantime, I have changed every capacitors (mostly with axial, because I had several in stock), and when I plug the instrument.... nothing happens  The motor doesn't run, the lights doesn't shine, I hear or see no sign of life.
I got the unit as untested, and I didn't want to plug it before recapping it (considered the amount of leaky and busted caps). I carefully changed the capacitors one by one, caring about the polarity, so (unless using dry-slug tantalums is mandatory), I think there is something wrong elsewhere.
The fuse seems ok.
When I noticed that the unit wasn't behaving as expected (motor not running, etc), I didn't dare to keep the mains plugged for more than a couple seconds.
I guess I will have to send it to a profesionnal repairman, as I am not used to work with 220V-powered effects.
Could it be a dead trafo?

[PRR]

Red-end electrolytic caps were common in the USA; they have fans. One guy did low-V Al much better than the old-line e-cap makers.

Today's Aluminum electrolytics will replace old Tantalum 99+% of the time. The Al guys decided to steal the Tant gang's business, buoyed by price hikes and mine wars; the Al guys just upped their game. Favor "LL" or "Low Leakage".

The factory used the just-enough values because mass production is only a few pennies away from going broke. 30 years later, if we still care, then we will invest the several extra cents per cap to up-size. Higher voltage may last longer. Higher uFd may extend the bass, usually nobody notices; but also gives some margin for eventual fade-way.

[Rob Strand]

The fuse seems ok.
When I noticed that the unit wasn't behaving as expected (motor not running, etc), I didn't dare to keep the mains plugged for more than a couple seconds.
I guess I will have to send it to a profesionnal repairman, as I am not used to work with 220V-powered effects.
Could it be a dead trafo?

With the power disconnected, measure the resistances of the transformer primary windings and secondary windings.  You can also do a continuity/resistance test from each terminal of the mains plug through to the transformer - you want to see close to zero ohms on each mains terminal (not a higher resistance through the transformer windings).

As mentioned in your video the unit has a main supply selector on the front panel.   If someone connected 240V when the selector was on 120V it can fry the transformer.   The fuse usually protects is but maybe not if someone jockeys-in a large fuse.

[snk]

Today's Aluminum electrolytics will replace old Tantalum 99+% of the time. The Al guys decided to steal the Tant gang's business, buoyed by price hikes and mine wars; the Al guys just upped their game. Favor "LL" or "Low Leakage".

Thank you, PRR.
I Learned something (I didn't know that kind of caps), and I know that I can use electros instead.

If someone connected 240V when the selector was on 120V it can fry the transformer. The fuse usually protects is but maybe not if someone jockeys-in a large fuse.

Eek : I wonder if the selector wasn't set on 140V (instead of 220) when I received it. The first thing I did was to put it on 220V, but who knows what the previous owner did?
The fuse inside is 1A.

With the power disconnected, measure the resistances of the transformer primary windings and secondary windings.  You can also do a continuity/resistance test from each terminal of the mains plug through to the transformer - you want to see close to zero ohms on each mains terminal (not a higher resistance through the transformer windings).

I will try to check the resistances, but it might not be an easy task, because the individual pins of the transformer aren't visible : I can only see a bunch of wires going to the same place (unlike on a stompbox using a transformer -like a ring modulator or an Octavia-, where you have the primary pins on one side, and the secondary pins on the other side).

[Rob Strand]

I will try to check the resistances, but it might not be an easy task, because the individual pins of the transformer aren't visible : I can only see a bunch of wires going to the same place (unlike on a stompbox using a transformer -like a ring modulator or an Octavia-, where you have the primary pins on one side, and the secondary pins on the other side).

A simpler test is to remove the power and measure the resistance across the mains plug when the power switch is on.
If it's open then something is probably wrong.

If that happens, you could then try say setting the voltage selector to the lowest voltage setting to see if you get a reading at all.

If you still don't get a reading you might have to press another button to enable power.

***** Whatever you do, if you change the voltage selector don't for forget to change it back to 230V. *****
*****  Change it back straight after the test. *****


It's hard to eye ball the size but say it's around a 20VA transformer.  For a 230V 20VA transformer you might expect to
see about 100ohms across the primary.

Here's an off the shelf 20VA and the primary resistance for 230V is 120ohm.

https://docs.rs-online.com/414f/0900766b800adc8c.pdf

For a unit with a voltage selector the primary will be tapped and you might expect a bit lower, perhaps down to 75 ohm on the 230V setting.   On the lower voltage settings you would expect lower voltages than the 230V setting.

No point splitting hairs since we don't know if it's 20VA in the first place.    For a 30VA transformer we expect lower resistances and for a 10VA higher resistances.

The transformer pic here looks a lot larger than 20VA!

https://reverb.com/item/29954806-meazzi-echomatic-vintage-tape-echo-delay-and-preamp-mixer