Demystifying comparisons between eBay managed payments and the old way Hint: it's still the old final value fees (before cap) + payment processing fees (analogous to Paypal)

Most often when we sell on eBay, we receive Paypal payments, so we ended up paying eBay’s commissions (also called the final value fee, FVF for short) and Paypal processing fees as a percentage of the sale.

Now eBay pushes out Managed Payments (MP) which combines payment processing fees with the eBay commissions (FVF) because eBay now manages the payment gateway. The rest is every time you sell something, you get a payout (sales – fees) deposited directly to your bank (it used to be collecting paypal balances then withdraw it).

They have a different calculation formula which they claimed the sellers are better off in most cases, but should we take eBay’s word for it? Regardless of whether you are enrolled in managed payments, the fee percentage for each sale depends on:

  • eBay store subscription level
  • category

It’s impractical to do the side by side fee structure comparison to see when we are better off for each sale, plus we cannot easily switch between the two plans.

It’d be very helpful if we can put the managed payment fee structure on the same form as the conventional eBay+Paypal fee structure, and figure out under what conditions we are better off or worse off with managed payments.

Initially I was ready to do the derivations to put both plans on the same scale, but I spotted that managed payment (combined) percentage is simply the vanilla (non-managed) eBay category final value fee + 2.35% payment processing fees! That’s how they’ve calculated the combined managed payments percentage!

This makes life a lot easier. Since I can factor out the 2.35% that applies to the whole sum (which also include shipping and sales tax) regardless of the fee cap, this works exactly the same as Paypal (which charges 2.9%) and we are getting a 0.55% discount in payment processing fees.

For managed payments, since we’ve already separated out the payment processing fees, the fee cap applies to the vanilla final value fee portion which is equivalent to the old eBay final value fee. Keep that in mind.

The part that has changed is the fee cap. The old way caps the commissions/FVF directly regardless of product category, yet the new way (managed payments) caps the sale price that are charged commissions. This means the fee cap goes up or down a little depending on the final value fee percentage class applying to your sale.

eBay set the (commissioned) sale price cap to closely match the realized commission cap in the old way, for example non-store subscriber who will have their raw final value fees capped at $750 will see the same cap for the most common 10% categories (12.35%-2.35% = 10%) because the (commissioned) sale price cap is $7500, which $7500*10%=$750.

Big industrial equipment also have the same cap regardless because $15,000*2% = $300.

For non-store subscribers, 10% is the anchor (iso-fee-cap) category. So you are a little worse of with books (price cap +2%) and better off with musical instruments (price cap -6.5%). 

For store subscribers, you get a bit more break over the fee-cap (lower) because your final value fee percentage is lower than the anchor (likely they chose a breakeven point at 10% when determining the sales price to cap final value fee over. Just easy numbers, not rocket science):

Managed Conventional Discount*
Common (9.15%) $2,500*9.15% = $228.75 $350 (Small stores)
$250 (Big stores)
$121.25 (Small stores)
$21.25 (Big stores)
Heavy gears (1.5%) $15,000*1.5% = $225 $250 $25
Books (12%) $2,500*12% = $300 $350 (Small stores)
$250 (Big stores)
$50 (Small stores)
-$50 (Big stores worse off)
Guitars (3.5%) $2,500*3.5% = $87.5 $350 (Small stores)
$250 (Big stores)
$262.5 (Small stores)
$162.5 (Big stores)

I call Basic/Premium ‘small-stores’ and Anchor/Enterprise ‘big-stores’.

So here are the observations, which is all you need to know:

  • Under managed payments, small-stores gets a better deal than big-stores, because the advantage of the $100 lower fee cap with big stores are eliminated with variable fee caps.
  • The breakeven line for small stores ($350 cap) is 14% fees ($350/$2500), which the highest category is 12% so far. This means small-stores are ALWAYS better off switching to managed payments.
  • The breakeven line for big stores ($250 cap) is 10% fees ($250/$2500), which the only category above that right now is books (12%). Big-stores selling BOOKS are worse off with managed payments.

So in other words,

  • everybody is better off with managed payments (fee-wise) EXCEPT big-stores selling books
  • under managed payments, there’s no final value fee advantage for being a big-store

* Remember you got 0.55% discount over the payment processing portion of the fees too and is not shown here since we’re just talking about savings in vanilla final value fees.

As far as books (12%) is concerned, if you are a big-store owner, your raw commissions cap raised from $250 to $300 because $300 = $2500 * 12%. But if you factor the 0.55% discount, if the sale price is $x,

     $$ (0.12-0.0055) x = 0.1145x > 250 $$ $$ x > 2183.4 $$

Since the raw commissions stops at $300 ($2500 * 12%), the additional $50 cap increase starts to get offset (and turn out positive as the processing fee discounts outweighs the commissions cap increase) when the payment processing discounts ABOVE $2500 covers all of it:

     $$ 0.0055(x-2500) > 50 $$ $$ x>11590.91 $$

So the range of sale price x which the only setup (books for big-store sellers) can do worse is

     $$ 2183.4 < x < 11590.91 $$


There are some ambiguities (technically incorrect documentation) on eBay’s website which implied vanilla final value fees (portion) are charged for sales tax. I made a sale and checked the numbers and it’s not true. Only the 2.35% payment processing fee portion is charged against the sales tax (like paypal for handling extra money), the category final value fee (in my case 9.15%) is not applied to the sales tax.

They actually meant “the 2.35% payment processing fee portion” when they said “managed payment final value fees”. This is also part of the reason why I wrote this article, because they do not use the language that conceptually separate the two portion of the combined final value fees (vanilla final value fee + payment processing fee) in managed payments, thinking that they are simplifying the math for sellers, without realizing if the two concepts really fused into one, they’ll be shortchanging sellers over sales tax.


The $0.3 fixed per-transaction fee applies to both managed payments and the conventional way (Paypal also charge +$0.3 fixed per-transaction), so nothing has changed.

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FREE oscilloscopes for innovators in response to #ChinaVirus #CCPvirus

https://www.humgar.com/CCPvirus-Urgent-Innovation-Response/

In the time of national emergency against the Chinese Communist Party Virus, or #CCPvirus in short, we are glad to offer FREE basic 100Mhz oscilloscopes (or mixed-signal oscilloscopes) to makers and engineers in the US who are stepping up with innovations to help.

Example include:

  • Simple ventilators that can be built quickly within US (https://www.agorize.com/en/challenges/code-life-challenge)
  • Robots that reduce direct human interaction with the infected patients
  • Machines that sanitize the contaminated environment quickly and efficiently
  • Any innovation you can come up with to help the front-line medical staff, produce the medical supplies we need, improve the logistics, and means to slow the spread.

Just send me (to wonghoi@humgar.com)

  • a project description
  • why you need the oscilloscope
  • whether you need the logic analyzer function (mixed-signal)
  • does your project require fancy oscilloscope features like FFT, calculus, phase difference, deep memory, talking to the PC
  • your name, address and phone number for shipping

and I’ll make the arrangements immediately.

Currently available models (subject to availability)

  • HP 54645A
  • HP 54645D
  • Agilent 54622D (Mixed-Signal)
  • HP 6632B Systems Power Supply (20V, 5A, Fast recovery)

These models has a no-brainer learning curve for any motivated maker/engineer who are up to the game innovating something serious. Time is ticking. We want you to use the oscilloscope right away! Higher bandwidth oscilloscopes are available as loaner if your project justifies it.

It’s on an honor system. Please don’t abuse the program so the innovators who genuinely need the oscilloscope will have what they need!

We thank all the innovators who contribute their time and effort in response to the CCP virus outbreak!

Stay safe, wash your hands, and stay home whenever practical.
Save lives by slowing the spread within our medical system’s capacity.

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Stanford SRS PS350 High Voltage Power Supply Repair

I received two PS350 power supply units that one of it has sparks when output is enabled and the other just won’t output anything at all.

The only repair info I found is from one of my favorite youtube channel the Signal Path. However, his unit has a much easier problem: the solder joints cracked because PS350 uses the metal case as a shield that are subjected to mechanical stress.

However, after difficult troubleshooting, I realized one unit has a fried resistor in the HV section, and a few core MOSFETs shorted.

The other unit is much more difficult: not only the HV capacitor is blown, resistor is blown, diodes shorted (won’t be able to detect it by probing in-circuit because of the capacitor ladder), PCB trace to the feedback path vaporized (without that the voltage will rise uncontrollably until something’s fried), and a bunch of MOSFETs, transistors and regulators ICs needs to be replaced.

Likely both units are broken because the users switched polarity without turning the HV section off (and let the voltage bleed out). This is very important and the markings on the case already warned the user NOT to do so.

You absolutely must NOT change the polarity while the output is live because the components in the HV section are marked for 4~6kV, so there is little room for a voltage spike past the operating voltages. The act of switching out the polarity (by mechanically swapping the pins through the dial switch at the back) doubles the voltage stored in the capacitors in a voltage multiplier ladder, so you are almost sure to crack the HV capacitors and likely the HV diodes.

Since I’ve developed experience for repairing SRS PS350, since I had to reverse engineer some of the circuit sections, I welcome request for repair evaluation (no fix, no fee). Please call me at 949-682-8145, or meet me at www.humgar.com.

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A Positive Tektronix Customer Support Experience

I often have bad experience with Tektronix product’s design (user convenience, reliability and repairability issues), and the by policy poor support for discontinued products. So far I have yet to get a chance to say good things about Tektronix while Agilent blew them out of water in these 4 areas.

Nonetheless, I have something good to say about Tektronix today. I have a DPO4000 series oscilloscope that the knob and busing popped out during shipping and disappeared, so I had to order them from Tektronix.

The operator on the phone noticed the part numbers and was aware that it’s a common problem that the jog shuttle’s knob and busing (for the Wave Inspector feature) often come loose, and offered to send it to me for free. That’s excellent customer service. The part that I admired the most is that they proactively acknowledged their design weakness and make amends.

Seems like Tektronix takes good care of their customers as long as the models are still supported. Definitely a redeeming quality!

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Data Precision 8200 Repair Service

I just bought a big lot of Data Precision 8200 and some Analogic AN3200 DC Voltage/Current Calibrators with a bunch of hard to find (unobtainium) genuine parts (relays, switches, hardware, regulator and amp ICs, whole modules, transformers) that that I believe it’s the leftovers of a closed down repair shop.

That means I’ll have all the materials needed to service and upgrade Analogic / Data Precision 8200 that you are unlikely to be able to find elsewhere.

Data Precision 8200 is the official unit to field adjust TDS 500~800 series oscilloscopes as the automation software (GPIB) was hard-coded to this model. Nonetheless, I find it a reliable reference for verifying oscilloscope performance and adjusting my multimeters as well.

Call me at 949-682-8145 for a repair quote or if you are interested in buying a unit. GPIB and 1kV option can be ordered for extra, either with the unit or service upgrade.

 

 

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Tek Evil: Repairing MDO4000C Series MDO4014C stuck at splash screen on start

I recently got a repair evaluation order that took me two intense weeks to nail the problem. It’s a MDO4104C that does not get past splash screen.

Worst of all, the unit failed right within 3 months right after the warranty expired. The unit didn’t show signs of heavy use. In fact, I nailed the problem so I can tell for sure the unit DIED OF NATURAL CAUSES. It’s not the first time I (and other people on forums like EEVblog) bitch about Tek designed their unit to last beyond the support/warranty period. This one takes the cake.


Basically everything in MDO4000C series happens in the main acq board. Anything that goes wrong there you might as well just buy another unit.

It runs embedded linux (uboot) and it’s slow to boot as I always expected from Tek (Keysight/Agilent use VxWorks for their modern embedded scopes and they boot fast).

There are no UART debug consoles anywhere and the only two test points with digital signals that idles high at 3.3V. The data pulses are quite long for the frame, and one of them looked more like clock bus in either SPI or I2C. So no UART. The firmware file mentioned BDI3000, which is a JTAG, which I suspect there’s a 10 pin IDC (ribbon) port on the right hand side of the main acq board, but this is as much as what I can get getting debug info.

There’s a RS-232 driver chip on the peripheral board, but it goes to the ID pin of the VGA port. I didn’t see any data traffic on it on boot.


Getting stuck at the splash screen practically tells you nothing about what’s wrong. The only thing you can infer from it is that the unit powers on and the display/keyboard is good. This is pure evil. HP/Agilent/Keysight designed their products to make it easy to service, and Tek has always a pain to service, and the new ones are no exception.

They don’t even mark the grounds in test hook points. It’s just a bunch of TPXXXX numbers. Apparently they are there for testing the design, not repairing it.


It’s obvious from the way they designed their product to the service manual, Tektronix definitely don’t want any people to do board level repairs: ultimately they want you to blindly send it in for factory repair within the first 5 yr of production, and make you buy a new one if the model is discontinued.

Despite I hated it, Tek has a valid strategy. If a product is cheaply made, even at the cost that it only last long enough through their warranty period, the manufacturer doesn’t even need to bother with board level repairs because it’s cheap for them to just give you a new part instead of figuring out what’s wrong with it.

Putting the frustrating to use UI designs aside, Tek works if you are a company buying the scope for a short 3 yr project. I wouldn’t recommend Tek at all if you plan to buy it for a long haul (because they are not designed to last given ones I’ve serviced), or plan to use it as a daily troubleshooting scope (because their user interface is slow and clumsy).

Tek has a huge following from the analog days when they did things right. Ever since the digital age, the learning curve for Tek’s UI was so steep that inevitably it turned into a customer lock-in where Stockholm syndrome kicks in.

Nonetheless, Tek was a little ahead of Agilent in terms of the MDO concept that correlates time domain measurement with the built-in spectrum analyzer. If that’s a feature that is important to you to the extent that you are willing to live with Tek’s clumsy UI and it might break down right after the warranty expires and it’s nearly impossible repair it yourself, it’s reasonable to go with Tektronix for this one given the lack of functional alternatives. Do NOT get MDO3000 series for this reason though, since the spectrum analyzer and oscilloscope are not time-correlated there’s no material innovation out there. MDO4000 series and up are time-correlated with the spectrum analyzer.

Again, I’m not saying Tek is bad. Tek is just mean towards their customers from a product design’s point of view, when you contrast them with how considerate (nicely thought-out) HP/Agilent/Keysight products are designed. Tek is still much better than the RCCC (Random Cheap Chinese Crap) in every way.


EDIT (2017-07-02): I just got a call this morning from somebody who bought a TDS 220 from me years ago. The BNC connectors broke off and he’s found somebody selling a kit specifically to fix the problems in TDS 200 series. That’s pathetic. I knew the design was obviously flimsy back in the days, but I trusted the Tek engineers knew what they are doing given their brand reputation. Turns out common sense is right. A bad design cannot last even if they had solid parts/manufacturing.

From my experience opening up many Tek and  HP/Agilent/Keysight units so I can compare their mindfulness, I can see that Tek is one of those high pressure companies that cut corners to get stuff out fast with low manufacturing costs. It’s not necessarily a bad thing from a business standpoint, it’s just Tek and HP/Agilent/Keysight operate with very different set trade-offs (or say, philosophy). Apparently Tek’s kind of trade-offs makes their used equipment a terrible choice unless it’s covered by their extra warranty.

Since I deal with old gears, I’m not impressed with the outcomes of used Tek products that I have/had. If I were to buy from Tek, I’d rather lease it since I do expect their product to last beyond their warranty period without multiple breakdowns that are costly to fix. My experience with used HP/Agilent/Keysight gears is that the problems are more predictable, limited to a small area and easy to reach and fix. For example, the caps in power section and CRT driver of TDS 500~700 series starts to fail, and the flyback transformer dies year after recapping the SMDs, and the units were just sitting there, not actively used. On the other hand, early 54600 series are almost always problem free other than an occasional cheap capacitor in the CRT driver drying up. This gave me a very bad impression about how Tek’s made their stuff.

Even if I could lease Tek products on other people’s budget, I still won’t consider until they radically changed their clumsy user interface and autoscale algoritm.

So far I haven’t see the kind of extra attention to detail in Tek products when I put it side by side with HP/Agilent/Keysight. This is how corporate culture reflects in their products: if you treat people well and trust them, they’ll get to all the nooks that managers and processes can’t reach and do it right. Tek just did enough that it will work as marketed, but whatever that’s cannot be objectively claimed in the advertisements, you are on your own.


I have spare parts to repair MDO4104C, MDO4054C, MDO4034C, MDO4024C

If you have an oscilloscope that you’d like to send it to me for repair evaluation (no fix, no fee), please call me at 949-682-8415 or email owner@humgar.com.

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Keysight Calibration (Performance Validation) for Probes Specifically 1152A

I recently sent a 1152A probe for calibration and was surprised to find out the data on the calibration report tells little about how the tests are done and under what settings. I searched the throughly and called tech support and they confirmed my observation the performance validation procedures are not mentioned anywhere in the published documents.

I called Keysight cal department and was able to reach a super-helpful tech, Markis, who did the calibration for my 1152A probe and he explained to me how the calibration process is done when I called.

HP/Agilent/Keysight probes using AutoProbe interfaces are powered by 1143A (that was intended for 54701A probes) through a N1022A adapter (the one used in 81600 Infiniium DCA) for Keysight’s calibration process, which measures uncompensated probe-only performance. I saw the calibration reports from 3rd party-labs, and probes are are calibrated inside the oscilloscope they are used in, and therefore it’s measuring a compensated system (scope+probe) performance.

There is a 30 minute warm up period.

The procedures resembles to what’s detailed in the old 1144A probe user/service manual, (page 10-14) with the exception that the ‘Gain Accuracy’ done there is ‘AC gain accuracy’ (at 1kHz, 1Vrms) instead of ‘DC Gain Accuracy’ claimed on the report. In fact, given that it’s simply measuring relative error (multimeter reading of the probe BNC output divided by the 5V Fluke Calibrator reference) at one voltage setting, I believe it should be called ‘DC measurement accuracy’. The number on the calibration report was divided by 10 times since 1152A is a 10:1 probe.

The bandwidth test for 1152A is simply looking at attenuation at the advertised bandwidth (2.5Ghz for 1152A) relative to 50Mhz (low frequency reference set at 0dBm).

 

 

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I see dead processor, the first time in my life I've dealt with hundreds if not thousands of PCs since I was a kid

Ever since I got my hands into assembling and troubleshooting PCs when I was a kid, both through my own experience and general consensus in the computer hobbyist community, CPU is almost the last thing to suspect at fault for a non-functioning computer, much less likely if:

  • There are no signs physical damages (mechanical or heat stress)
  • There were no shorts (burning electronic smells)
  • There weren’t any extreme overclocking (at least Vcore was pumped)
  • The computer used to boot, but has some random hangs

After 20+ years (and troubleshooted a few hundreds if not a couple of thousand PCs), today I encountered (actually zeroed-in that it’s the culprit) the first bad processor in my life. It was inside a M815G motherboard from a 54854A oscilloscope that I bought that wouldn’t boot into windows without random ‘file corrupted’ errors. Then after a few tries, the board wouldn’t even boot, not even any code on the POST card.

At first I suspected it’s an aging motherboard, since I checked the RAM and passes Memtest86+ on another board. It’d be either the motherboard or CPU, which I never considered it might be the CPU given how unlikely it is both by other people and myself.

I couldn’t be bothered to dig at the moment so I simply replaced the entire motherboard (with CPU and RAM installed) with another unit and confirmed that the 54854A I bought didn’t have any deeper problems. Then I put this ‘bad M815G motherboard’ on my back burner.


Today I was trying to revive a VP22 motherboard (which boots only if I apply pressure on certain areas of the PCB) that didn’t have the Fan+Heatsink+CPU+RAM. I happen to have a spare Pentium 3 and some PC-133 (SDRAM) lying around, but not the heatsink+fan, so I borrowed it from the M815G in the repair-if-I-feel-like-it pile.

The VP22 booted with pressure on the PCB (beeped, checked POST card) but I couldn’t see any display, so I thought of swapping-in the known-‘good’ CPU from the ‘faulty’ M815G to see if I had the wrong revision that the VP22 didn’t support. The VP22 used to get stuck in the boot process, but at least the POST card has a reading, this time after swapping in the CPU from the M815G, it has no POST code at all. No pulse.

I got suspicious and took the the CPU from the VP22 and put it in the ‘faulty’ M815G. Guess what? The M815G in question boots and runs fine!!! WTF! For all that time I thought my M815G has a difficult fault just because I had a marginally failing an then dead CPU, which I didn’t even consider the possibility given how unlikely the CPU is at fault.

And no, it’s not the thermal compound drying up, it’s freshly applied every time I move it to a different motherboard. The CPU was only used in M815G/VP22 which does not even have any means of overclocking. No burns or smells or physical damage, and the computer used to boot. The CPU just died of natural causes.

A black swan day!

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Aging problem just from storage Working 6632B stored for 10 years has a failed tantalum cap

I fired up one of my 6632B stored for almost 10 years and smelled burned electronics, despite everything is functioning. I tested the unit immediately when I bought them a decade ago and it was working fine, so it’s an example where electronics can deteriorate by storing (even in temperature controlled, dry environment).

Since I see smoke, I turned everything off immediately and investigated. Turns out one of the tantalum capacitors in the processor/controller board gave in:

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