I'm trying to fix a Pioneer DV-S6D DVD player that is not powering on ( stand-by light just blinks). I checked out the pcbs, and the problem seems to be with either a few diodes and/or the ceramic cap on the PSU PCB (PSU Assy VWR1316).
Main issues seem to be:
1) Ceramic Cap C151 appears slightly toasted, so I will desolder and test out of circuit (not done yet)
2) I have tested all of the diodes in-circuit and those that appear problematic are as follows: D104 (Zener diode MTZJ2.4B), D311 (leads to +5V rail after passing through IC311), D411 (leads to +3.3V rail after passing through IC411), and D811(leads to EV.+5V)
I can't identify the specs of these three diodes D311, D411, and D811, since the parts list only shows these as proprietary Pioneer component numbers (D311=VZF1076, D411=VZF1075, D811=VZF1054). Can someone help identify what replacements I can potentially use for these diodes
? Thanks in advance for any advice/support.
Main issues seem to be:
1) Ceramic Cap C151 appears slightly toasted, so I will desolder and test out of circuit (not done yet)
2) I have tested all of the diodes in-circuit and those that appear problematic are as follows: D104 (Zener diode MTZJ2.4B), D311 (leads to +5V rail after passing through IC311), D411 (leads to +3.3V rail after passing through IC411), and D811(leads to EV.+5V)
I can't identify the specs of these three diodes D311, D411, and D811, since the parts list only shows these as proprietary Pioneer component numbers (D311=VZF1076, D411=VZF1075, D811=VZF1054). Can someone help identify what replacements I can potentially use for these diodes
? Thanks in advance for any advice/support.Attachments
Firstly, SMPS like these are dangerous to work on unless you are well versed in the hazards and in how to handle the board.
As to the components, the ceramic cap will almost certainly be OK. It looks like normal discolouration that occurs on these types of cap in service. Unless the zener is proved faulty I would suspect that is OK too. Its a low value and won't test well on a DVM. The diodes must be high speed/soft recovery types. General stand ins are devices such as the BY399 etc Ultimately, the real cause of failure is likely to be failed or failing electroylitics and not just the obvious large ones. It would be normal practice to replace all of them. The power diodes must be tested for leakage with one lead isolated.
For the diodes on a heatsink you need to identify whether they are two or three lead pakages and search accordingly. Examples,
http://cpc.farnell.com/jsp/search/b...ParametricAttributeId=&prevNValues=411+205707
Hi Mooly,
Thank you very much for the quick reply and great advice. I am quite new to PSU repair, so I am taking as much precaution as I can in working on the board, including discharging the main and secondary caps, working with rubber insulated gloves etc (reading up and building my knowledge base as primary precaution of course).
In terms of the diode D411 with the heatsink, I've checked the diode out and it's a two lead package. The identifier on the diode looks like 97 D5S4M and when I searched on the web, I found that it seems to be a Shottky rectifier (SBD) 40V 5A - does this seem correct?
Since you mentioned the electrolytic cap failures, I will also desolder the larger filter caps and check them out of circuit. If these caps turn out to be bad, I guess I will have to replace the caps and those diodes with the replacement you had mentioned (BY399).
One other question for you if I may. Since I don't know the Vf or Ifsm ratings on those two diodes (D311 & D811), is it OK to use a BY399 to replace them or do I need to worry about exact voltage and current ratings? BY399 is rated at 800V and 3A, but I don't know if the current in the PSU through these diodes is higher or lower than 3A for example. Thanks again for any advice you can provide!
Thank you very much for the quick reply and great advice. I am quite new to PSU repair, so I am taking as much precaution as I can in working on the board, including discharging the main and secondary caps, working with rubber insulated gloves etc (reading up and building my knowledge base as primary precaution of course).
In terms of the diode D411 with the heatsink, I've checked the diode out and it's a two lead package. The identifier on the diode looks like 97 D5S4M and when I searched on the web, I found that it seems to be a Shottky rectifier (SBD) 40V 5A - does this seem correct?
Since you mentioned the electrolytic cap failures, I will also desolder the larger filter caps and check them out of circuit. If these caps turn out to be bad, I guess I will have to replace the caps and those diodes with the replacement you had mentioned (BY399).
One other question for you if I may. Since I don't know the Vf or Ifsm ratings on those two diodes (D311 & D811), is it OK to use a BY399 to replace them or do I need to worry about exact voltage and current ratings? BY399 is rated at 800V and 3A, but I don't know if the current in the PSU through these diodes is higher or lower than 3A for example. Thanks again for any advice you can provide!
The 40V/5A Shottky sounds reasonable. The BY399 is a general purpose high speed diode that's great as a universal replacement but as always, there are countless more modern devices available. A good clue as to diode specs is to look at what rail the diodes produce and the voltage rating of the reservoir caps on that rail. Small reservoir cap, and its a low current rail. But they must be high speed devices.
Some devices appear as and are drawn as diodes but are in fact over voltage protection devices. These are fitted across the rails. If it uses any of these, and any are short, then the correct device must be used. If you omit them, then its "user beware". If the PSU developed a fault in the future the rest of the electronics in the DVD player would be at risk.
Checking caps on a meter is no good. They fail by developing a high E.S.R. (equivalent series resistance) which means the cap often still has its marked value but the impedance it presents is very high (like a flat 9 volt battery that will still read 9 volts off load). They should all be replaced with 105C (temperature) low E.S.R. caps suitable for SMPS. No cheap generic parts for these.
Some devices appear as and are drawn as diodes but are in fact over voltage protection devices. These are fitted across the rails. If it uses any of these, and any are short, then the correct device must be used. If you omit them, then its "user beware". If the PSU developed a fault in the future the rest of the electronics in the DVD player would be at risk.
Checking caps on a meter is no good. They fail by developing a high E.S.R. (equivalent series resistance) which means the cap often still has its marked value but the impedance it presents is very high (like a flat 9 volt battery that will still read 9 volts off load). They should all be replaced with 105C (temperature) low E.S.R. caps suitable for SMPS. No cheap generic parts for these.
Hi Mooly,
Just wanted to let you know that you were on the money with your advice.
I replaced 99% of the capacitors with low E.S.R versions and did the diode
replacement as well and my DV-S6D is back in working order. I checked the
old caps out of circuit and as you mentioned the uf values were as marked,
but with a high E.S.R being the culprit. Thank you again for your great advice!
Just wanted to let you know that you were on the money with your advice.
I replaced 99% of the capacitors with low E.S.R versions and did the diode
replacement as well and my DV-S6D is back in working order. I checked the
old caps out of circuit and as you mentioned the uf values were as marked,
but with a high E.S.R being the culprit. Thank you again for your great advice!
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