I'm an amateur at repairing electronics. I have fixed obvious issues on electronics before, but I could use some help on this fix. I picked up a Pioneer CLD-D504 laserdisc player that won't power on. There is no standby light. I was told it may have gotten wet but I see no obvious water damage. It had a blown fuse. I've downloaded the service manual. Nothing, including the fuse itself, says wether it's fast or slow blow, but I'm guessing it's slow, seeing as its right at the point where the AC power goes to the PS. I'm guessing it's the standby power that's "bad". I put in another fuse and it blew as soon as I plugged the player into the wall. I completely removed the PS from the chassis so it was not connected to anything. I replaced the fuse. As soon as I plugged it into the wall, that fuse blew. I've started measuring components on the primary part of the PS while still "in circuit". I haven't removed anything. The first thing I noticed was that R2 measures 2M ohms. I believe it should be 22.5 ohms. Could that be the "problem"? What should I measure next? I've ordered a pack of new fuses that should be here in a couple of days. Thanks!!!!!!
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Need help with PS blowing fuses.
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Re: Need help with PS blowing fuses.
Originally posted by stj View Postcan you link or upload the service manual.
it's probably a shorted diode or bridge rectifier.
is this arcade-related??
http://manuals.lddb.com/LD_Players/P.../CLD/CLD-D504/
Arcade related? Did I post this in the wrong forum? Sorry
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Re: Need help with PS blowing fuses.
Originally posted by stj View Postbtw, check the main transistor on the heatsink too.
leave R2 alone if you want to live - it links the mains neutral to the metal chassis!!!!!
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Re: Need help with PS blowing fuses.
Originally posted by JimBanville View PostThanks. I'm measuring all this with the PS unplugged. Does that R2 impedance reading of 2M ohms sound right? Does still being in-circuit affect that reading?
to blow a fuse you need a short - so probably a diode or transistor near the fuse.
the fuse should be a "T" or time-delay aka slowblow type - preferanbly ceramic.
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Re: Need help with PS blowing fuses.
Originally posted by stj View Post2meg is about right.
to blow a fuse you need a short - so probably a diode or transistor near the fuse.
the fuse should be a "T" or time-delay aka slowblow type - preferanbly ceramic.
I measured Q1 on the heat sink in diode mode. It's marked ground drain source. When I measured it with + on the S, I get .41v on D and .57v on G. When I reverse leads and measure with - on S, I get 1.9v on D but it drops to 0v within a second. I get 0v on G. When I touch the G D S in continuity mode, I might get a quick tone, but I'm not getting a continuous short.Last edited by JimBanville; 03-11-2021, 08:20 AM.
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Re: Need help with PS blowing fuses.
Originally posted by stj View Post2meg is about right.
to blow a fuse you need a short - so probably a diode or transistor near the fuse.
the fuse should be a "T" or time-delay aka slowblow type - preferanbly ceramic.
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Re: Need help with PS blowing fuses.
Originally posted by stj View Post2meg is about right.
to blow a fuse you need a short - so probably a diode or transistor near the fuse.
the fuse should be a "T" or time-delay aka slowblow type - preferanbly ceramic.
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Re: Need help with PS blowing fuses.
Originally posted by stj View Post2meg is about right.
to blow a fuse you need a short - so probably a diode or transistor near the fuse.
the fuse should be a "T" or time-delay aka slowblow type - preferanbly ceramic.
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Re: Need help with PS blowing fuses.
Originally posted by stj View Postdesolder d6 and see if the recifier d1 loses the short.
d6 sounds fucked.
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Re: Need help with PS blowing fuses.
Originally posted by stj View Postdesolder d6 and see if the recifier d1 loses the short.
d6 sounds fucked.
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Re: Need help with PS blowing fuses.
Originally posted by stj View Postnone of the rectifier pins should be connected to each other,
but it is soldered parallel to d6 - so you cant tell which is bad without removing one.
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Re: Need help with PS blowing fuses.
Originally posted by stj View Postgood.
btw, the reason for a ceramic fuse is simply that when you have a mains-short like here, it can actually break a glass fuse and create a big mess.
most originals are glass unfortunatly - to save a few penny's
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Re: Need help with PS blowing fuses.
I would highly recommend that you use a 100 watt incandescent light bulb instead of the fuse just in case you have issues and blow the fuse again
When doing this the light bulb with glow bright for a couple of seconds and dim down to maybe nothing or very dim depending on how much current you are drawing from the switching power supply
If for some reason the light bulb is bright and does not dim down then there are issues with this power supply
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