I received a "broken" Sony STR-DH500 from a friend and I'm on a mission to fix it.
When I plug the receiver into 110V and tap the power button, all I hear is a single relay click and then...nothing. No PROTECT, no error message, no additional clicking.
Can someone start me on a path on how to troubleshoot the thing?
I've opened it up, cleaned it out, disconnected everything externally (speaker wires,...) and checked for visual damages on the circuitboard and components.
I just need some help getting started.
A link to a service manual would be great too, if it even exists
When I plug the receiver into 110V and tap the power button, all I hear is a single relay click and then...nothing. No PROTECT, no error message, no additional clicking.
Can someone start me on a path on how to troubleshoot the thing?
I've opened it up, cleaned it out, disconnected everything externally (speaker wires,...) and checked for visual damages on the circuitboard and components.
I just need some help getting started.
A link to a service manual would be great too, if it even exists
check regulators for voltage ,mains secondary fuses , transformer and so on ...there is a posibility that the click comes out of stand by relay and circuits but if fuses or trafo is gone makes sense that you hear or see nothing
this is no project for an amature ....you need skills to trouble shoot amplifier like that if you need schematic please email me
regards sakis
this is no project for an amature ....you need skills to trouble shoot amplifier like that if you need schematic please email me
regards sakis
Sony does publish good service manuals. Like all service manuals, they don't include instructions on how to troubleshoot, but include schematics. Helpfully, the schematics are usually marked up with expected voltages and waveforms at many important nodes. If you can't find it elsewhere, try Agoraquest - Great Sony Forum, News, Reviews with 90,000 members
Sony amp power supplies are based on a separate standby and main power transformer. It seems the standby power works since you hear that click upon pressing the power button. You should find an AC power board inside, this will have a small transformer (for the 12 VDC standby power supply), a relay, and various supporting components. This relay should allow AC into the big main power transformer. Try measuring for 120 VAC at the primary of the main power transformer. This is a good time to mention that there are deadly AC and DC voltages inside a receiver so use caution and do this at your own risk. There is probably a fuse for the main power trafo primary, as well as some or all of the secondaries. When replacing fuses, never use anything but the same type and rating (current and fast/slow blow). If the thing is blowing fuses, you can't fix it by putting in a higher rated or slow-blow fuse. You will only cause more damage. The VFD display is powered from the main power trafo so no display tells me there is maybe a blown primary fuse. (The secondary for the VFD usually isn't fused).
Can you turn it on and off with the remote? If so, the system microcontroller is basically functioning, which is good.
Sony amp power supplies are based on a separate standby and main power transformer. It seems the standby power works since you hear that click upon pressing the power button. You should find an AC power board inside, this will have a small transformer (for the 12 VDC standby power supply), a relay, and various supporting components. This relay should allow AC into the big main power transformer. Try measuring for 120 VAC at the primary of the main power transformer. This is a good time to mention that there are deadly AC and DC voltages inside a receiver so use caution and do this at your own risk. There is probably a fuse for the main power trafo primary, as well as some or all of the secondaries. When replacing fuses, never use anything but the same type and rating (current and fast/slow blow). If the thing is blowing fuses, you can't fix it by putting in a higher rated or slow-blow fuse. You will only cause more damage. The VFD display is powered from the main power trafo so no display tells me there is maybe a blown primary fuse. (The secondary for the VFD usually isn't fused).
Can you turn it on and off with the remote? If so, the system microcontroller is basically functioning, which is good.
I took the receiver apart and tried to measure voltages at various points throughout the system.
The stand-by transformer seems to work and send 110V to the main transformer. I checked the input leads of the main and it does get 110V, but it's outputs are all zero.
I disconnected the transformer and did a resistance check on the primary and secondary windings. All secondary windings came out as a short, as expected, but the primary winding is giving me an open-circuit (infinite resistance).
I thought it's more likely to burn up secondary windings than primary windings, but apparently something went poof with the primary windings or some solder joint to the windings.
Where could I get replacement Sony transformers (Bando brand) for my unit? What's the expected cost of one?
The stand-by transformer seems to work and send 110V to the main transformer. I checked the input leads of the main and it does get 110V, but it's outputs are all zero.
I disconnected the transformer and did a resistance check on the primary and secondary windings. All secondary windings came out as a short, as expected, but the primary winding is giving me an open-circuit (infinite resistance).
I thought it's more likely to burn up secondary windings than primary windings, but apparently something went poof with the primary windings or some solder joint to the windings.
Where could I get replacement Sony transformers (Bando brand) for my unit? What's the expected cost of one?
It does appear that the primary winding is open. However, many transformers have an internal fuse or temperature sensitive device that, once opened, stays that way. You might be able to take apart the transformer and find it. So the transformer might be good, just that the thermal device failed. Worth a look, I think.
The device is usually around the size of a small fuse and wrapped in insulating tape. Yours could be different.
The device is usually around the size of a small fuse and wrapped in insulating tape. Yours could be different.
You can try to find a replacement transformer at sony parts direct: https://servicesales.sel.sony.com/ecom/accessories/web/index.jsp or by phoning them. They will sell service parts to individuals, and they will help you look up the part over the phone.
Part number is 1-445-622-11 (also marked as Bando BD31B1-0012 and BEM1-DIW)
The service manual (thanks sakis!) states that the fuse within the transformer is non-replaceable, and I wouldn't know how to repair/reset/replace a thermal fuse without any guidance. Can those be replaced easily? Where do i get a replacement and how do I know what rating to get?
The service manual (thanks sakis!) states that the fuse within the transformer is non-replaceable, and I wouldn't know how to repair/reset/replace a thermal fuse without any guidance. Can those be replaced easily? Where do i get a replacement and how do I know what rating to get?
I think if you use a fuse you can get away without a thermal protector. It's more for meeting regulations than for actual protection. I have bypassed those in the past with no repercussions. Of course, I take no responsibility for what you do, but that's what I do.
To get to it, you must remove and partially disassemble the transformer. It shouldn't be buried too deeply.
To get to it, you must remove and partially disassemble the transformer. It shouldn't be buried too deeply.
Update: After an hour of frustration with an exacto knife and needle nose pliers I was able to "pull" out the thermal fuse, which was sandiched between the primary and secondary windings.
The markings say:
22JR UMI
3.5A 250V
7A 125V
145C PL
<PS>E YET
Next I'll bypass the fuse to see if I can get the receiver to power up.
But now I'm looking to find a 7A/125V axial thermal cutoff fuse for a proper fix.
Where can I get one? Are any of the other markings crucial?
The markings say:
22JR UMI
3.5A 250V
7A 125V
145C PL
<PS>E YET
Next I'll bypass the fuse to see if I can get the receiver to power up.
But now I'm looking to find a 7A/125V axial thermal cutoff fuse for a proper fix.
Where can I get one? Are any of the other markings crucial?
If you replace it with another thermal fuse, yes, I think you could use a higher amp rating one, with the same temperature rating. Of couse you always can always add a current limiting fuse in line with the AC cord if you are concerned about that.
Your method of attaching the thermal fuse is very important. Don't just solder the wire leads onto it, as the heat will probably blow the fuse. Usually you use crimp connectors. Those often come with the fuse if you buy at retail; I don't know if bulk fuses from Digikey etc. would include them.
Thermal fuses are rated to blow at the Functioning Temperature.
Your method of attaching the thermal fuse is very important. Don't just solder the wire leads onto it, as the heat will probably blow the fuse. Usually you use crimp connectors. Those often come with the fuse if you buy at retail; I don't know if bulk fuses from Digikey etc. would include them.
Thermal fuses are rated to blow at the Functioning Temperature.
Thanks macboy, i'll take a look at some electronics places to see what they have.
Otherwise i'll just order something from Digikey/Newark.
I bypassed the fuse for now and the receiver powers up!
But of course, it shows the dreaded PROTECT and shuts off after 1-2 seconds.
I've tried resetting the unit to its shipping mode and tried other factory menu start-ups but they all end up with the error message.
I've ohmed out the speake terminals (none shorted) and nothing else is connected...what else could this error message indicate? What do I check now?
Otherwise i'll just order something from Digikey/Newark.
I bypassed the fuse for now and the receiver powers up!
But of course, it shows the dreaded PROTECT and shuts off after 1-2 seconds.
I've tried resetting the unit to its shipping mode and tried other factory menu start-ups but they all end up with the error message.
I've ohmed out the speake terminals (none shorted) and nothing else is connected...what else could this error message indicate? What do I check now?
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