2018-08-27
Radeon 4850 (Asus EAH4850/HTDI/512M/A)
FCO-716A generator, 100MHz - apparently one and only on the board
8x Qimonda HYB18H512321BF-10
16M x 32bit (512Mbit) GDDR3, up to 1000MHz
RJK0353 MOSFETs from Renesas: 30V, 35A, 5.2mOhm, 4.5V gate drive
TPC8107 - Toshiba MOSFET,
uP6101B - synchronous-rectified buck controller specifically designed to operate from 5V or 12 supply voltage and to deliver high quality output voltage as low as 0.6V (uP6101A) or 0.8V (uP6101B/C)
Operating at 300kHz.
LCX74: dual D-type flip-flop with Asynchronous Clear and Set inputs and complementary (Q, Q) outputs
P3055LDG - N-Channel Logic Level Enhancement Mode Field Effect Transistor, 30V, 50mOhm, 12A
AZ7805D - 1.0A 5V regulator
SN74AHCT125DGVR
uP7706 - 3A ultra low dropout linear regulator, 200mV @ 2A dropout voltage, 1.2...5.5V input, regulated output down to 0.8V.
Pm25LV512 - 512kbit serial Flash.
Card was not working correctly. Artifacts were visible right from the BIOS screen and Windows was crashing in the first few minutes. I've removed cooler, cleaned up thermal paste (large amount of cheap silicone), put some flux around main chip and all memory chips and heat it up with hot air. I'm not sure how long this would last, but it fixed the card at least for now.
2018-07-28
ZoltriXound PC speakers
Cheap PC speakers from ancient times.
Idle voltage from transformer is close to 12V RMS, after rectifying ~15.4V and dropping by ~1V when playing. Transformer is heating quite a bit.
Amplifier should be able to provide few hundreds mW per channel, although it seems to be working outside of specified voltage / load impedance range.
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| 2W, 4Ohm speakers, magnetically shielded |
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| 601M marking By the date on the plastic it looks like speakers were made in 2002. |
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| EPC-S601M310 881015 VER 1.0 |
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| Transformer: ETS-S2BO9021 230V/9V, 0.2A |
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| SP2822 amplifier (most likely equivalent of TDA2822M) |
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| Apparently soldering wires on copper side was faster / cheaper. |
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| 470u for power supply filtering, 220u at output |
2018-07-16
Zelmer Z28Z010 iron repair
Zelmer is Polish brand with long tradition, although these days its production is probably in China like for everyone else.
Most tricky part of disassembling for me was screw hidden under hard to remove (thigh latches) "extra steam"/sprinkler buttons.And this is what failed - thermal fuse MICROTEMP G4A00 240C, 10amps, 4mm diameter. Connected to wires with crimps, put in silicone tube and held by metal plate at heating element.
I'm assuming that bimetal thermal regulator is working fine and thermal fuse just tripped prematurely. Its characteristics says that it must trip at 240C, it must hold (holding temperature or Th) at 200C but it is also susceptible to aging so over time it might fail at lower temperature.
I've bought replacement (5pcs described as NEC Microtemp SF240E) on ebay for 1.49USD including shipping and reused original crimps.
2018-07-14
Nady 49 MINI wireless microphone/receiver set
Wireless microphone + receiver set from 1989.
49HT-01 REV.A
NE571N - dual channel compressor/expander
NE5534 - well known low-noise opamp (single)
MC1458 - dual opamp
CA3089 - IF amplifier and FM detector
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