Hey guys, yes, two scopes are cool and I bought the 2235 back in 1989. I was working at HP at that time and I was perceived as an heretic to buy scopes from a competitor : ) But HP oscilloscopes, in my opinion, could never compete with the TEKs. I had to replace the flyback transformer on this one after 15 years of service and it was not fun to fix the self-relaxing supply: a cleverly-designed type but a mess to troubleshoot. Then I had the opportunity to obtain a TEK 2465B which was not working properly and I fixed it, good for another decade : )
Now, without a scope, I could not...
Clunche
Member
"I am a power supply designer and I introduced numerous integrated circuits for power conversion."
Last Activity: 05-01-2024, 01:43 AM
Joined: 03-01-2020
Location: Toulouse
-
Hello Jean-Louis, the board I fixed was driven by a UCC28515 which is a combo PFC + 2SW forward from TI. Once the MOSFETs are removed - you need to extract the whole heatsink at once, with 5 TO-220 to unsolder - you can supply the daughter board with a 12-V dc supply and make sure the driver signals are observed at the MOSFETs gates:
[ATTACH=JSON]{"data-align":"none","data-size":"medium","data-attachmentid":3262309}[/ATTACH]
The standby power supply uses an ICE from Infineon but needs a sense of the input line to start...Leave a comment:
-
Hello,
I have spent time on a Corsair HX620 in which the fuse was blown as well as one of the two SPP24N60C3 like reported in one of the posts. I've successfully removed the heatsink which hosts the two MOSFETs, the diode (a STTH8S06D) and the two MOSFETs for the 2-switch forward converter. None of the small bipolars in the driving stage were dead and waveforms from the UCC28515 daughter board were good, despite quite a large duty ratio in lack of feedback (transistors removed, 230 V applied). The standby power supply needs 230 V ac to operate, it did not start up with dc applied...Leave a comment:
-
Re: Pioneer SC-LX81 - loudspeaker terminals
Hi Stj, thank you, this is actually what I did as the plastic was ok and it worked. One of the banana screw thread was dead so I managed to secure it with a nut inside so the only connection means now is via a 4-mm banana plug but it seems to work now.
The new problem I've found is pretty weird and I don't know if it was there before I dismantled the whole thing (what a mess!): it works well when operated in any configuration of Dolby for a long time. Then, if I suddenly switch to Advanced surround, there is a kind of low-frequency...Leave a comment:
-
Pioneer SC-LX81 - loudspeaker terminals
Hello everyone,
I am currently working on a Pioneer SC-LX81 amplifier and I successfully ran a firmware upgrade fixing the network issues. I have found the file [URL="https://home.hccnet.nl/hans.nieuwenhuis/images/"]here[/URL].
The problem I am having comes from a defective 3-terminal loudspeaker connector whose previous owner destroyed the PCB connections. I don't know how this happened because I don't think the guy ever opened the received - never seen such a complicated architecture with numerous stacked boards and flat ribbons! -and the plastic is secured... -
Re: pioneer vsx 2021 no sound
I have finally identified a 3.3-V regulator which was guilty for not powering the digital assy clock section, just like what one of the poster from India reported. It is IC9512 and it's a NJM2872BF33. You can check voltage on the top side of the digital board by probing the voltage across C9609. I had around 1 V while C9601 nearby was receiving the 5.6-V input. To replace this TSOP-5, you need to access the bottom of the digital board. When back in place with a new reg. the clock signals showed up ok and the CD input plays fine but sometimes it stills...Leave a comment:
-
Re: pioneer vsx 2021 no sound
I have finally found the manuals for the LX55. You need RRV4230, RRV4204 and RRV4194. They can be downloaded in the link supplied by Madana1 for the first ones but at different location for the third and most useful one:
RRV4230, RRV4204: [url]https://www.hifiengine.com/manual_li...vsx-lx55.shtml[/url]
RRV4194: [url]https://www.hifiengine.com/manual_library/pioneer/vsx-1121.shtml[/url]
You need to freely register to download these manuals. Seems like the RRV4194 is the one needed for full assembly description with...Leave a comment:
-
Re: VSX LX-55 no sound at all
I have tried to find a data-sheet for the TI DSP D810K013BZKB4 but could not find any. If someone has a source for this technical document - so that I can at least probe some of its pins - I would appreciate. Thanks!Leave a comment:
-
Re: pioneer vsx 2021 no sound
Nope, no luck either, they don't have it, I am familiar with this good site. I've checked some Russian sites as well and I did not find it.Leave a comment:
-
VSX LX-55 no sound at all
Hi gents, I have bought a second hand VSX LX-55 AV amplifier from Pioneer and the blue light was flashing without display at first power on. After testing the switching power supply, I realized I could simply reset the amplifier: the display is back and all functions work well like Internet radio and stuff. The problem is the absolute lack of sound in any configuration. I've tried the many options and ended-up entering music via the CD inputs, no luck, desperately silent. I know these amplifiers have a TI DSP (D810K013BZKB4) and they often die bringing a typical error. But not here, no error at... -
Re: pioneer vsx 2021 no sound
Very kind of you to provide this link, thank you. I downloaded the two manuals but unfortunately they are incomplete and very short (8 pages only each): no schematic diagrams of the boards found in the LX-55. Would you have another suggestion where to look? I have tried many different places unsuccessfullyLeave a comment:
-
Re: pioneer vsx 2021 no sound
Hello, I own a second-hand VSX LX-55 which is similar to the VSX-2021 that you fixed. The issue is probably the same, I have no sound at all even in direct mode via the CD inputs. I have tried to locate the service manual but could not despite my many attempts. Would someone be kind enough to share a download link for this manual so that I can start tracking down signals on the HDMI board? Thanks a lot. Chris.Leave a comment:
No activity results to display
Leave a comment: