Majestic DVX-478 USB repair brief

Received with 90% failures on startup sequence. Some swish comes out from inside during startup.

Investigation revealed the swish as originating from the lens touching the dvd support  as soon as the autofocus procedure starts.

Tweaking the F (focus) trimmer less that 1/16 of degree clockwise cured the problem. The trimmer is located on the laser pickup.

PS: how to turn a trimmer 1/16 of a degree is left as an exercise to the student..... :=))

Riduzione tempo di risposta del sensore FAPI domotica art. n. 30006

(Sorry for italian here!)

Sostituire il condensatore elettrolitico da 10uF 25V indicato nelle figure con uno da 0,47uF 25 Volt.Il tempo di reazione alla rilevazione si riduce a meno di un secondo

condensatore da sostituire	Punti di saldatura interessati
Manuale pagina1	Manuale pagina2

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Zyxel Prestige 660-HW ADSL2 router repair brief

Don't trash your Zyxel,
...possibly it only needs a full CAPS replacement. 

This page describes a couple of successfull repairs concerning a Zyxel Prestige 660-HW ADSL2 router.

Lightning.

After a summer storm I have found my Zyxel 660Hw out of order. It has received a voltage surge from the ADSL line.
Reconstructing PCB lines behind the ADSL socket fixed the problem.

 

Unstable LAN connection.

With age, my Zyxel 660-HW started to be instable on all 4 LAN connections. All other functions were fine.
Symptoms were: poor LAN performances and continually loosing all LAN connections and soon reestablishing them (every 15 seconds or so).

The cause was the electrolytic CAP highlighted red in the aside picture.

Replacing that cap cured the problem.

Most of the electrolytic CAPs measured bad ESR values. In particular a couple in the power supply (marked in yellow in the previous picture).

Shouldn't you have a chance to measure ESR, my suggestion is to replace all electrolytic CAPs. 

Philips CD-670 CD player: a CDM2 pickup surgery

This old CD player came to me from a flee market for 15 EU. Not so much for a CDM2/10 transport and a TDA1541 (non-A) DAC.
It is in good shape but it randomly failed to read CDs.

After a lot of testing on the transport controller and power suppliers electronics, laser power adjustment, etc. ..my attention was driven toward the CDM2 transport itself. You know, it is a beautiful galvanometric transport (the arm swings like needles in galvanometers..) ..but it is prone to failures.

I cleaned the lens and double checked the foiled PCB. Nothing.

Playing with the transport (remove-check-reinstall-test cycles) I got random results. I was not able to reproduce a predictable sequence of behaviours... BUT....