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Post by cobba1231 on Dec 1, 2022 9:44:03 GMT -5
HI,
The SC-LX85 receiver behaves as follows.
When it works (there is an output to the speakers, the menu modes are switched) at some point, after about 5 - 15 minutes, it goes into protection. POWER ON appears on the screen. At the same time, when the ON button is briefly pressed, nothing happens. You can turn it off only by holding the ON button for a long time (about 7 seconds). Further, if you press ON, it may immediately turn on, and then after a while, the relays may click and the POWER ON message will appear again. If you wait for a while (from 5 - 10 minutes), the receiver again can spontaneously turn on and work normally.
RESET (simultaneously pressing ENTER + ON button) does nothing. Sometimes, when the receiver enters protection, it allows you to reset, and sometimes not.
5.6v duty stations are stable and always present.
3.29v, 1.79v are stable when the ON button is turned on and do not disappear when the receiver is in protection (POWER ON display).
Tell me what is the possible problem?
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Post by cobba1231 on Dec 7, 2022 11:22:57 GMT -5
Hi.The problem was in the capacitor C9577. Under load, the throughput resistance increased to 14 ohms. For this reason, the voltage of the chipboard 1.8v decreased to 0.85v.How to indicate that the topic can be closed?   |
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Post by Admin on Dec 7, 2022 15:22:20 GMT -5
Nice work. Did something leed you to test at that location or were you just testing various line voltages?
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Post by cobba1231 on Dec 8, 2022 6:18:17 GMT -5
Hi.
I wrote in the first post that everything is fine with a voltage of 1.8v. It really is. But I did not measure this voltage further down the circuit. Near the chipboard, it turned out to be 0.85v. And I began to find out because of what the tension decreases. I measured the resistance between the PWM stabilizer 1.8v and the blocking capacitor near the chipboard. It turned out to be 14 ohms when the board was warm. When the receiver is not working for a while, the resistance becomes 0 ohms. Thus, I found a faulty capacitor C9577. I did not find such a consulator, but I installed 3 0 ohm jumpers on the process contacts. The capacitor itself showed normal capacitance and but normal ESR.
Sorry for my bad english)
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Post by xXFREDBERTXx on Dec 8, 2022 16:11:35 GMT -5
Wow that was a very nice error find from you 😎
These seems a NEC Tokin issue and these dry out and fail than 🧐 These NEC Tokin capacitor fail now day’s on all kind of devices from laptop (DELL) or PS3 and also on GPU‘s from different manufacturer's ☺️
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Post by andyb1712 on Dec 8, 2022 17:11:16 GMT -5
This is an interesting find... the LX85 and 86 have these filter caps fitted but although they are shown in the LX87 schematic, they are shown as NM, not mounted. I guess Pioneer decided to stop fitting them.
Your repair says you fitted 3 x zero ohm links instead of replacing it if I read it correctly? Does this work OK like this?
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Post by cobba1231 on Dec 9, 2022 6:52:40 GMT -5
Wow that was a very nice error find from you 😎 These seems a NEC Tokin issue and these dry out and fail than 🧐 These NEC Tokin capacitor fail now day’s on all kind of devices from laptop (DELL) or PS3 and also on GPU‘s from different manufacturer's ☺️ Capacitor capacitance is normal. ESR is also ok. The problem was the increase in resistance from 1 ohm to 14 ohm under load. Therefore, I did not install a new capacitor, but shunted input 1 and output 3 of the capacitor with three resistors of 0 resistance. The board has additional heels for other board revisions.  |
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Post by cobba1231 on Dec 9, 2022 6:56:01 GMT -5
This is an interesting find... the LX85 and 86 have these filter caps fitted but although they are shown in the LX87 schematic, they are shown as NM, not mounted. I guess Pioneer decided to stop fitting them. Your repair says you fitted 3 x zero ohm links instead of replacing it if I read it correctly? Does this work OK like this? In different revisions, the boards are installed by different components. In my revision, exactly as I showed.) I could not find a datasheet for the NEC TOKYA OG476 capacitor. Maybe you have a datasheet?  |
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Post by andyb1712 on Jan 1, 2023 9:27:12 GMT -5
I found a data sheet online for this part. It doesn't seem to be critical to the unit function because some models have it fitted and some don't. The LX56 is fitted with a simple inductor compared to the LX86 with the NEC Tokin part.   Attachments:NEC Tokin Data.pdf (567.17 KB)
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