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Why attribute that to me?

I didn't write the statement you quote as being mine,
but I can see where it would make sense.

Try it this way:

Pink paint can be used to repaint a red fire truck,
but pink paint is not recommended to repaint a red fire truck.

-Chuck Harris


On Fri, 26 Mar 2021 12:40:58 -0700 "Jim Adney" <jadney@...>
wrote:

On Fri, Mar 26, 2021 at 01:46 PM, Chuck Harris wrote:

A 2 type can replace a 1 type. A 2 type is
not recommended to replace a 1 type.

Pretty sure there's a typo in here somewhere.... ;-)

On Fri, Mar 26, 2021 at 03:01 PM, Chuck Harris wrote:

Why attribute that to me?

The misattribution was due to the way groups.io quotes text, but I'm the one who wasn't paying attention, so I'll accept the blame. For the record, the quote actually came from Mark Vincent.

To clear things up, the types mentioned in question are X and Y caps. The X1 can replace an X2 and a Y1 can replace a Y2. The reverse of these is not recommended, e.g. X2 replacing an X1.

Mark

I received the material from Mouser, for those interested I report the list of what I found available and I ordered:
/g/TekScopes/files/mouser%20TEK2465.xlsx

More or less everything corresponds to what was found on this group, except the 7 ohm NTC, I found one that should be fine with code 995-SL157R005-L. However I did not use it because the 2 original NTCs measured with the ohmmeter, report the correct resistance.

For those like me who are not familiar with the Mouser catalog, I think I can say that, for example, the codes 647-UHE1E101MED, 647-UHE1E101MED1TA, 647-UHE1E101MED1TD correspond to the same component but in bulk, or taped etc.

I started working with the A2-A3 boards and I have some questions, if anyone would like to answer:

- I found R1016 swollen, then unsoldering it broke, what to replace it with? A common metal or ceramic film?

- I followed the method of searching for the shielded outer end of non-polarized capacitors with the oscilloscope but for several specimens I don't get any difference, or uncertain differences by inverting the connections on the pins. Yet the test clearly works by trying some old capacitors found in my drawers. Does this mean an error on my part, or that for those components the direction of insertion is indifferent?

- Still speaking of non-polarized capacitors, in the wiring diagram does the shielded outer end correspond to the curved line of the capacitor symbol?

Thank you for any information already received and in the future and I apologize for any errors but I'm using google translate....

Gio

Hi!
Not having received any recommendations for my last post, I had to fend for myself.
I finished replacing the components on A2, A3, A5, A9. Having no way to build the load for the power supply due to lack of suitable components, I just double-checked the job over and over again, then held my breath and pressed ON.
After a moment of suspense, the oscilloscope started up regularly and with satisfaction I saw that the screen and readout are much more defined and clear than before.

For information, here is a table with the ESR values ??that I measured with an "AVR Component tester" of both the old and the new capacitors. Despite the possible limitations of the instrument used, I was surprised to find significantly higher ESR values ??in the new 10uF 160v and 3.3uF 350v capacitors compared to the old ones removed from the instrument.

Furthermore, I found that the old capacitors removed have a capacity equal to or greater than the imprinted value, while the new ones on average almost always have a capacity lower than the rated value (data not shown in the table).
Orig.Value OLDValue ESRold ESRnew New Cap Mouser Part# Note
.056 uF 250v 58nF 12,00 12,23 594-2222-372-41563 Film capacitor .056uF 10% 250VDC Vishay sp10
.068 uF 250v broken broken 10,33 594-222233810683 Safety capacitors .068uF 20% 440VAC Vishay X1 17.5x8.5x15sp15
1 uF 50v 1uF 3,50 0,76 505-MKS2C041001FJC00 Film capacitors 63V 1uF 5% Wima 7x5x10sp5
10 uF 100v 15uF 0,60 3,50 647-ULD2C100MPD1TD Aluminum Electrolytic Capacitors - Radial 160V 10uF 20%
10 uF 160v 11uF 0,63 3,50 647-ULD2C100MPD1TD Aluminum Electrolytic Capacitors - Radial 160V 10uF 20%
10 uF 25v To do ---- 0,52 647-UPW1V100MDD Aluminum-radial electrolytic capacitor 35volt 10uF AEC-Q200
100 uF 25v 102uF 0,45 0,12 647-UHE1E101MED1TA Aluminum-radial electrolytic capacitor 25volt 100uF 6.3x11sp2.5 20%
180 uF 40v broken broken 0,07 647-UHE1H331MPD1TD Aluminum-radial electrolytic capacitor 330uF 50volts 10x25sp5
22 uF 10v To do ---- 0,28 647-UHE1H220MDD1TD Aluminum-radial electrolytic capacitor 50volts 22uF 5x11sp2 20%
220 uF 16v To do ---- 0,30 647-ULD1C221MPD1TD Aluminum Electrolytic Capacitors - Radial 16V 220UF 20%
250 uF 20v 300uF 0,15 0,07 647-UHE1H331MPD1TD Aluminum-radial electrolytic capacitor 330uF 50volts 10x25sp5
290 uF 200v 290uF 0,13 0,19 647-UPW2E331MRD Aluminum Electrolytic Capacitors - Radial 250volts 330uF AEC-Q200 22x50sp10
3.3 uF 350v 3,8uF 2,97 4,20 647-UPW2V3R3MPD Aluminum-radial electrolytic capacitor 350volt 3.3uF AEC-Q200
4.7 uF 10v 4,7uF 1,30 0,21 505-MKS2B044701KJC00 film capacitors - Wima 4.7uF 50 Volts 5%
4.7 uF 35v 4,7uF 2,00 0,72 647-UPW1H4R7MDD Aluminum Electrolytic Capacitors - Radial 50volts 4.7uF AEC-Q200 5x11sp2
47 uF 25v 45uF 0,45 0,36 647-UHE1E470MDD1TD Aluminum Electrolytic Capacitors - Radial 47uf 25V 105c 25V PET

Now I still have a bag of capacitors for the A1 board and am very undecided whether to replace them or leave the old ones that show no obvious signs of swelling or electrolyte leakage. In addition to the complexity of removing the A1 card, I am concerned about the possibility of static currents damaging it while I do the job. What precautions should I take to avoid the worst?

Gio

On Wed, May 12, 2021 at 05:27 PM, iv3ddm wrote:

I found that the old capacitors removed have a capacity equal to or greater
than the imprinted value, while the new ones on average almost always have a
capacity lower than the rated value

Yes, that's a fairly common representation.
Electrolytics are generally specified as +/- 20% capacitance.
To save costs, manufacturers will cheat slightly on the low side - it's a fact of life.

THEREFORE, feel free to select capacitors of slightly higher capacitance, in order to meet the original bare number value.
Furthermore, if you understand the circuit, feel free again to double or triple the original capacitance value, for increased performance and reliability.
This is especially applicable in SMPS applications.

Remember, it's all a matter of cost - saving $0.11 (total per PSU) on low-spec units multiplied by 1 million PSU's manufactured, is a lot of money saved.
But it's also a lot of environmental waste, when stuff gets trashed before its time.
And somebody (our grandchildren) is going to have to pay for the environmental clean-up.

When I overhaul TV PCB's, I have a standard procedure to at least double the capacitance values in certain parts of the circuit.
Especially at the high frequencies in these PCB's, ripple current capabilities become paramount, and these caps will run cooler and last longer than the original specc'd units..
My incremental cost increase for using higher spec caps is less than a couple of $, which is absolutely insignificant when related to the total repair cost, so why be stingy and skimp?

Film capacitors are generally reliable (except for these paper RIFA's and others), and will show similar ESR readings, irrespective of age.

Of course, YMMV.