Repair of a vintage 1990s Sony Stereo system HST-D105. Noisy channel. speakers cut out. FIXED

[@markrhine5809]

Dear Mr. Pier, I really do enjoy watching you repair electronics, you make it look so easy, I designed and built a user amplifier based on the LM386 IC, I used two of them for stereo, I built this project in 2014, and I used on my TV with 7 inch speakers it sounds very good.

[@JordanPier]

Good that you're adventurous and into building circuits. Helps to understand how things work, which will help troubleshooting other things that have failed.

[@2flyabove]

That was some good detective work, and fortunately not too difficult to fix. Great video, thanks.

[@markrhine5809]

Dear Mr. Pier, Another great learning video for my collection, I really like the oscilloscope you are using I have an an Hitachi V212 20MHz and I am just learning how to use it, have a great 2023....

[@leeselectronicwidgets]

I opened it up, and my heart Sanken...

[@craigm.9070]

thanks for that demonstration of the "Relay Tap Test!" Can't dispute that video representation...That unit is lucky to be alive.

[@scrappy7571]

I know all too well about the speaker relay tap test. I did a complete recap and refurbish on my au717 amp. About 1 month later, the left channel would have no out put when first turned on. Increasing volume, it would come back on and work fine the rest of the day. Narrowed it down to the brand new omron relay with the tap test. Removed the relay and cover, to find one set of contacts not fully seating. Bent the contact a bit, and has been fine since. In the automotive repair trade new stands for "never ever worked" We see new chineesium parts defective right out of the box.

[@zx8401ztv]

Smashing repair jordan, very thorough and i always enjoy your vocal thoughts. Speaker relays are always something i dont trust. If the case comes off ill run paper or abrasive rubber through the contacts. Anything more abrasive than that, relay replace. But thats me lol.

[@rogerchurch3804]

are those little sankens amps for the rear channels what kind of outputs is the front channels ?

[@JordanPier]

In this application where small power is needed, they suffice for rear surrounds or for here in this low power unit. In the sony receivers where this is used as the surround channel amplifiers, the fronts typically would have been Darlington MN2488 and MP1620 with a upc2581V driver IC.

[@mwitwicki]

Do you know if there is a memory backup battery somewhere in the lbt-d105 radio? When the radio is turned off, I lose the set list of stations.

[@JordanPier]

There almost always Is. May be tucked behind the front, adjacent to the microprocessor chip.

[@Elfnetdesigns]

I have an off question. What type of solder braid are you using? I cannot seem to find any that is usable without dousing it in flux first and even then it is questionable if it will draw up solder or not.

[@JordanPier]

Chem-wik 10-50L #4. .100" wide

[@rodolforodriguez8108]

hola Jordan,perfecto el video,acabo de heredar un LBT-D105,uno de los canales no se oye,cuando lo reviso veo que en el lugar o placa donde usted cambio el SK 18752,falta la plaquita donde debe montarse.......como podria tener informacion para hacerme de ella,o un plano para que alguien me la fabrique porfavor.no soy electronico...gracias.

[@JordanPier]

Wish I could be of more help, but i no longer have the machine in my possession. If I did i could give you dimensions. You may be able to watch the video and get an idea of what it looks like, then experiment with metal materials to create what you need. Cant think if another way to do it.

[@josehugobarrerasanchez4396]

Muy buen estéreo y reparacion solo falto conectarle las bocinas para apreciar la calidad del sonido

[@poormanselectronicsbench2021]

Thanks for the view of the guts of the Sony. I recently picked up a Pioneer SA-950 Integrated amp at a good price, that had a "noisy channel" as well. It turns out that, it has a protect relay, similar to the one in Sony unit, only 3A rated, that has a 30 ohm contact resistance on both contacts. It also looks like, the Omron 8A package will be a direct replacement, even down to the 24VDC coil resistance ( Onmron's contact specs are less than 0.05 ohms per contact per the data sheet). I do wonder if, these relays go bad faster, because of the design of the circuit energizing the coils, as if they slowly come up to a voltage that pulls the contacts in, they man not have the solid "wiping" action that a instant 0 to 24V power up gives them, so, it may be easier to build up oxidation/corrosion on the contacts, and the "soft start" connection may also make it harder to cut through any crud that does build up over time.

[@71Fenderv22]

Someone MUST have a sentimental attachment to this thing. I have a sanyo era Fisher that is somewhat similar, and although I rarely ever use it, if it started acting up, I would trash it, it's just BPC....

[@justsumguy2u]

Sony made some junky stuff back then. I remember buying a used Sony receiver at a flea market, not realizing until later that it was once part of a rack system. The bass only extended down to around 60 Hz

[@scrappy7571]

My family had tons of Sony products back then. Every single item failed shortly after warranty expired. Only the Trinitron TV's lasted a long time. Now you hardly see any of their products for sale.

[@71Fenderv22]

They made some really good cd players, but thats about it... Oh and they had a few great higher end intergrateds, like the TA-F700es and the TA-F444/555es, but like Sanyo they made ALOT of bpc.....

[@joekrisocki2644]

Serious question. Is this economically worth repairing? Not sure how much you're charging the client for time and materials. Or is the purpose to just make a repair video? Thanks

[@JordanPier]

Is it really worth it? Probably not. For the owner? Sure. This had sentimental value and they still enjoy using it.

[@joekrisocki2644]

@@JordanPier Ok. I like that answer. Thanks

[@JZX834L]

Strange how that works. Could be as simple as someone passing on and you had listened to music on that device together. That's when a worthless obsolete device becomes something of value.

[@arturz5780]

​@@JZX834L It's quite decent LM1875 amp in AB class with 12W RMS output, very similar to LM 3886. Nowadays to get comparable sound quality to this old stuff you have to spend at least $300.