Aishi capacitors

[linker3000]

Re: Aishi capacitors

(Yay for old threads)

I'm just starting my journey through a Curtis-brand UK freeview DVR (DVB350UK) that won't power up. You can hear the power circuit trying though!

All caps are Aishi and the first two pulls are CD288Z 1000uF 25V with obvious top bulge.

First cap reads as 108uF with an ESR of 4.7R, second reads open circuit.

For control, a new replacement Panasonic FR reads 1009uF with an ESR of 0.59R

I'm going to replace the caps in the PSU circuit and hope the remainder (about 15 on this board 1 of 2) are under less electrical and thermal stress and so a bit healthier. Fingers crossed.

[jsalvagaia]

Re: Aishi capacitors

I've just replaced an Aishi CD288Z 105°C (470uF/10v) because it drawed down a 1.5v supply.

It's in a DSL router (Sagem 1201), and this cap was inserted in the filtering part of 1.5v supply voltage for the main processor.
A chain reaction on the 3.3v and 5v had the Power Supply Supervisor chip to reset main processor. So DSL router lost frequently ADSL carrier.

diagnostic was the following:
- AISHI cap was bulged
- capacity of 297 uF instead of 470
- measured leakage current at a 10v test was over 19mA !!

Replaced it by a 'spare' one : leakage of only 1.6 uA at same test voltage of 10v.

This router is working fine now, even if a second Aishi is filtering the 5v main supply... But let it a chance !

[ReeceyBurger123]

Re: Aishi capacitors

I see them on alot of vestel tv power boards and have never seen a failed one yet and they all check good, but I replace them any way. Aishi hmm........

[Behemot]

Re: Aishi capacitors

Some of the CD11xx names are actually series markings, but I have not found the CD81. Anyway, I've repalced them with Chemi-Cons KZG and Nichicons VZ and the peltier wine-refridgerator seems to be operating normally. It is two-zone fridge with two cooling boards, the lower one (cooling bigger copartment) was used more so it started messing sooner than the other one.

Will just also swap the input caps, 2 in series, they all have the same capacitance but very high difference in ESR.

[Pentium4]

Re: Aishi capacitors

Yeah I've noticed Aishi caps sometimes have legitimate series markings on them, and sometimes the generic CDXXX "series" markings. I've also had worse luck with their small caps. I recently had some fail in a Huntkey unit, however, it was a semi fanless unit with PPFC coil blocking a lot of airflow (When the fan was running) I'm not sure if they're having their caps rebranded, but I didn't think they were as bad as say, CapXon

[Behemot]

Re: Aishi capacitors

Anybody knows what CD81 series actually is? Seems like half of the AiSHi(t) caps are made by somebody else, maybe even different manufacturers. It has similar markings to Jianghai which uses this strange CDxx which than translates to line name according to series table. Both are incredible crap with even small caps failing like hell.

This site http://myxr.e.tradeee.com/product_vi...apacitors.html says it is low leakage current, which may mean anything. Judging from ESR of the less bad ones, I'd say it is some general purpose type, even than they have 10 such types and say each one is different…

[tom66]

Re: Aishi capacitors

Awesome! did you just randomly come up with this? I have been waiting for a way to power 3-5W leds in a small space such as a cfl base.

Yeah, I think it's unique to me. I've just cut the feedback from the two-transistor circuit (ringing choke converter) and adjusted the components for maximum efficiency and current regulation instead of voltage regulation. The clincher was realising that the current through the LED didn't need to be constant. After all, we don't notice the flicker from incandescents. So you can get away with basically no filter cap, and that's the number one failure. There's also no need to isolate the LEDs so you can get rid of y-caps and optos, the overvoltage protection is simply the resistor tied from the secondary thru the current limit transistor. It would cost less than $1 to produce in volume.

[ben7]

Re: Aishi capacitors

I was under the impression that most of those bulbs didn't even use a SMPS, just a large X-cap in series. This (fake uncertified) X-cap likes to catch fire so I consider the cheap LED bulbs as worthless crap. Also, the efficiency of 5mm LEDs is about the same as CFLs - probably worse. It's only when you get to high power LEDs that efficiency becomes really good.

Here's a schematic of a very cheap LED driver, but it works surprisingly well. It's efficient (83%), it's current regulated, doesn't use electrolytic caps and won't get hot pumping 4W into LEDs... hottest part is the FET at 180mW. And it reaches full brightness in ~3.5 milliseconds. It is a modification of the cheap two transistor circuit, but made more reliable by avoiding several electrolytics and modified so that the current through the LED is limited and proportional to the current supply voltage.

Awesome! did you just randomly come up with this? I have been waiting for a way to power 3-5W leds in a small space such as a cfl base.

[tom66]

Re: Aishi capacitors

I was under the impression that most of those bulbs didn't even use a SMPS, just a large X-cap in series. This (fake uncertified) X-cap likes to catch fire so I consider the cheap LED bulbs as worthless crap. Also, the efficiency of 5mm LEDs is about the same as CFLs - probably worse. It's only when you get to high power LEDs that efficiency becomes really good.

Here's a schematic of a very cheap LED driver, but it works surprisingly well. It's efficient (83%), it's current regulated, doesn't use electrolytic caps and won't get hot pumping 4W into LEDs... hottest part is the FET at 180mW. And it reaches full brightness in ~3.5 milliseconds. It is a modification of the cheap two transistor circuit, but made more reliable by avoiding several electrolytics and modified so that the current through the LED is limited and proportional to the current supply voltage.

[Scenic]

Re: Aishi capacitors

^ I know. We had a couple of those a while back and they all failed.
When the last one died (flickering and went out), I took it apart out of curiousity. One of the tiny 0.25W resistors was open. Replaced all of them, replaced the jumperwire labeled as F1 with a fuse and replaced the aishi capacitor (400V 2.2uF IIRC).
Worked well enough as a nightlight in the hallway, as it was already somewhat dim.
Now, half a year later, it's useless even as a nightlight. My LED flashlight with almost dead batteries is brighter..

[kc8adu]

Re: Aishi capacitors

that type of led bulb is junk regardless of mfr/brand.even cheap caps will outlast china 5mm led's.

I've seen them a lot in cheapo LED lamps (the ones with 20+ regular 3mm or 5mm LEDs).
They seem to just dry out instead of bulge.

Attached pic from a random ebay auction as an example

[imp]

Re: Aishi capacitors

LOL

[c_hegge]

Re: Aishi capacitors

Now that must be where Aishi get their electrolyte from - the employees with colds sneeze into the cans

[imp]

Re: Aishi capacitors

Just figured out that my sneezing sounds like "Aishiii" (I´m having a boring cold at the moment), so you can actually "hear" the brand .... Kind of ... But that doesn´t make it any good though

[c_hegge]

Re: Aishi capacitors

My general rule is that if you haven't heard of a brand, then assume it's bad.

[Scenic]

Re: Aishi capacitors

I've seen them a lot in cheapo LED lamps (the ones with 20+ regular 3mm or 5mm LEDs).
They seem to just dry out instead of bulge.

Attached pic from a random ebay auction as an example

[ben7]

Re: Aishi capacitors

The CFL was buzzing and flickering, I think it was causing at least half of the problems.

I can imagine, and we got this cheapy cfl that my dad bought, I bet it wont last a year, it buzzes when turned on and is very very very dim at startup, I bet its got say a 1uF cap or likely inside xD

[tom66]

Re: Aishi capacitors

depending on the circuit, it might supposed to have an impedance that high

The CFL was buzzing and flickering, I think it was causing at least half of the problems.

[Uranium-235]

Re: Aishi capacitors

Aishi seem okay... they claim a rather optimistic 12,000 hours for their caps used in CFLs... pulled one with an ESR of about 4.5 ohms, so not so sure about that claim!

depending on the circuit, it might supposed to have an impedance that high

[ben7]

Re: Aishi capacitors

Hehe yeah, I got loads of these 10uF 200v ones from cfls, I dont have an esr meter but I bet a few are bad. Only one is bulged, but thats because the cfl was used on a dimmer