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Hi yes schematics makes it hard going to do modifications or repairs. I cannot advise further about the power supply voltages.

Hi, Are you located in the UK, I can repair and service your Amplifier email audioamplifierservicing@aol.com

@@AudioAmplifierServicing I've just sent you an email.

Hi 2SB817 & 2SD1047 Sanyo genuine originals.

@@AudioAmplifierServicing yeh thought as much. Looks like i’ll wait until I have a list of parts for my other amps just to meet the minimum order amount from some of these companies. Thanks mate.

Hi not sure what you're asking, are requesting repair support?

@@AudioAmplifierServicing Yes

@@graemeyetts3465 The channel i for the repair and servicing of Audio Amplifiers?

Martyn from what your describing it does sound like the output transistors have failed, there may be other components in the failed channel that may also need replacing. With electronics it's if a device will fail it when. That can be due to many factors but also the component fails due to age related to it it's operational life. So I can not say a particular make or model of Amplifier is more or less reliable all have their own issues that develop over time. If your in the UK I can repair and service your Amplifier. If your not then email audioamplifierservicing@aol.com and I can provide guidance on self repair if you have experience and equipment.

@@AudioAmplifierServicing I am in the UK. Can you give me an idea of cost? Thanks

@@martynjohnson235 Hi please email audioamplifierservicing@aol.com

@@RonilPaclejan email audioamplifierservicing@aol.com

@@RonilPaclejan email audioamplifierservicing@aol.com

Email audioamplifierservicing@aol.com

@@RonilPaclejan email audioamplifierservicing@aol.com

No, no es normal, ¿puedes proporcionar más información?

@@AudioAmplifierServicing maestro colocó el tocadisco en el pre Ino suena

​@@cejonpino1168Hi I still do not understand what your asking or what the issue is

Yes

Hi measure the millivoltage across the emitter resistors and adjust to 22 millivolts or 50mA

@@AudioAmplifierServicing Hi there thanks for your reply that is what I have done I thought it would be 22mv but just couldn't get confirmation any where thanks once again amp is now running lovely and cool and cross over distortion is ok..Best regards Robert.

As detailed in the video email audioamplifierservicing@aol.com

Hi the written repair description for video details the part number for the potentiometer, you should be able to source it. If your in the UK I can of course repair you Amplifier email audioamplifierservicing@aol.com

Yes, it does look like the controller chip is damaged

The module is obsolete

Hi, there is no inherent design issue with the Amplifier, as with all electronic equipment electronic components can fail, this can be due to numerous factors. For example how the equipment is used, the environment the equipment is working in, etc. So if your Amplifier is still working, we'll after 11 years there is no need for concern.

@AudioAmplifierServicing awesome thanks just bought another from Ebay another question the seller states it's had cap upgrade and sounds better can u change caps in them cheers

@PhillGreen-qn1fl ​ Hi as with all Amplifiers you can upgrade capacitors and install higher quality ones, typically Japanese. But often changes in Audio quality for newer Amplifiers that are re-capped may not be that noticeable and is down to the user and what they hear. For Older Amplifiers the Audio quality and reduction in noise in the power supply sections and signal processing circuits may be significant as failing capacitors are replaced with new. This video provides insight ua-cam.com/video/0TOL9qAd32k/v-deo.htmlsi=5gbOQfbsVQuNQeCP

​got new one off ebay had crimped wire i replaced wire can u tell me if pololarity correct cheers and can u use any wire took cable out off old faulty denon dcd 510ae cd player @AudioAmplifierServicing 2:10

​@@AudioAmplifierServicingcan u not upload photos here ?

Hi email audioamplifierservicing@aol.com

@@AudioAmplifierServicing thanks for the reply, but I found it. It turns out it's a available freely.

Hi check the 4.7 ohm resistors in the failed channel they go open circuit but with no visual signs of failure.

Hi when you say the unit has power, are any of the front panel LEDs illuminated for example power and input selection.

Seems the underrated R7/R8 is also covered in this forum www.vintage-radio.net/forum/showthread.php?t=200509

Hi It is best not to use any solvent or liquid removal substances. Wear eye protection and use a plastic label removal tool. If the glue has dried out completely it will splinter as you remove it. Hence the eye protection. Also ensure no glue splinters fall between the legs of other components for example transistors.

​@@AudioAmplifierServicing thank you! I will do that.

As with many power amplifiers, there are no top case vent grills to allow for convection. Hence, the fan forces cool air across the metal heat sink and through the rear vent grill. The fan can be unplugged, or you may consider sourcing a low noise fan. If you do decide to disconnect the fan, the Amplifier does have over temperature protection, so it will prevent overheating. Heat generation is also dependent on how hard the Amplifier is being driven, so if you're not driving your Amp hard over heating may not occur.

@@AudioAmplifierServicing thx for the super fast response, much apreciated. Loud and clear what you saying, will try it out. I dont think im demanding a lot of the amp, its connected to Hepta four tune excellence speakers as pre-amp a Rotel rsp1066 and source a Denon dcd 725 all connected with Van Den Hull interlinks and speakercables. With proper powercords Furutech and Lapp Ölflex and Belden. Will come back to let you know how its going and to show some love to you channel. Much appreciated

​@@permsnThank you

Thank you

Hi, please refer to the description for the video it details what to check reference the transverse switch S8.

@@AudioAmplifierServicing thanks

Hi is that the channel that was getting hot

​@@AudioAmplifierServicingNot getting hot at all. It's been powered up for a week with no ill effects and sounds fine.

Okay

Hi do you mean this one, www.muzines.co.uk/articles/mosfet-amplifier/2651

Yes that's the one, I still have several of the modules knocking about, they were great value for money back in the day although with a slew rate of 10 V/uS they migt be considered a bit slow by today's standards.

​@stevesmyth4982 Yes, Maplin same name but very different www.maplin.co.uk/pages/electricals?gad_source=1&gclid=CjwKCAjwyJqzBhBaEiwAWDRJVAIoDbjgB1p_F4yEx9iulziEHFwLNW6uonWrjyYAnJc5M9PaJNmNkRoCulQQAvD_BwE

Hi the A300 squeal is normal as the unit has no speaker protection system. You can purchase such a circuit board and fit it into a case for example. www.amazon.co.uk/Speaker-Protection-AC10-18V-DC12-24V-System/dp/B0B7FM6M7J With reference to the Powersoft power Amplifier I would recommend contacting the company directly. www.powersoft.com/en/about/contacts/

Hi where did you purchase the Mosfets, was it from a reputable supplier for example Mouser or Digikey.

@@AudioAmplifierServicing I bought them from CPC. I have fixed these amps before by just replacing the Mofsets but this amp is a bit more stuborn

@@snipperacoustics Hi its good you have bought them from CPC as you know they are Genuine originals. I would recommend making a Dim bulb tester to aid with fault finding as you will get through your newly purchased components very quickly each time you power up the Amp. This is an example ua-cam.com/video/8YWqWabXdbo/v-deo.html use a 100Watt filament bulb. Refer to the service manual and turn the bias trimmer RV101 fully Anti clockwise, then check the voltages as detailed. Does the front panel LED change to Green and does the speaker protection relay change over?

Hi, can you confirm if only one channel of the Amplifier failed. If so, you can use the other channel as a reference to set the bias. First ensure you have no speakers connected or input signal. Set the volume controls to minimum. You need to measure the millivoltage across one of the Emmiter resistors of the working channel. Make a note of the value, then measure across one of the Emitter resistors of the repaired channel and make the adjustment. The Amplifier should be powered up for 15 to 20 minutes before adjustment, so the unit can warm up and stabilise. Before proceeding with the above can you advise if you have checked all the components in the failed channel? Normally when output transistors fail there will be high current flow which will damage other components for example emitter resistors and the driver circuit. Also, only power up the Amplifier after repair via a Dim bulb tester as this will prevent failure of new parts if there is still an issue. I trust you have purchased the transistors from a reputable supplier as there are many counterfeit component sellers.

@AudioAmplifierServicing unsure as was bought off ebay as a project...looks like they had attempted repair with different output transistors other than the ones marked on the pcb ...I had a yamaha amp that the microprocessor had failed in but the output transistors in it was fine and same as the ones that should have been in the ibiza amp hense why I didn't want to power up without checking everything those outputs are few and far between cos of fakes that are about....thanks for your reply really appreciate it , will probably just pull parts back out of it and skip it rather than blow up some perfectly good output transistors

Hi you need to contact the UK authorised service agent info@soundtech.co.uk

Excellent

Yes, but check the solder tracks for the unused pins to ensure you do not need to link them to the used pins.

@AudioAmplifierServicing thanks. When you sent me the link for the filters in the c352 amp I bought them and the difference in amp power is unbelievable. The old caps rattled. Do you have a link at all for the Nichicon filters you used in the C370? Mouser seems to be out of stock of quite a lot of 10000uf 80v caps

​@@tharkthax3960 Hi as with all components many have now become unavailable due to the market changing and manufactures choosing not to produce them. I can send you a bill of materials, but you would need to check availability with authorised suppliers for example mouser and Digikey. Email audioamplifierservicing@aol.com

@AudioAmplifierServicing thought I found some but the lead spacing are 10mm, need to 25mm. May well have to wait until July when more stock comes in. Cpc farnell I haven't tried but don't think they will have. Thanks again.

​@AudioAmplifierServicing hi again, I've ordered Cornell Dublier filter caps, 2 pin at 10mm pitch. I checked the board and it will accommodate the narrower lead spacing. 6.42a ripple. The original filter I removed is like you mentioned - loose internally. Thankyou again.

Hi Crown provide service support via Authorised service companies www.crownaudio.com/en/support

Hi Panasonic or any other high quality Japenese capacitor brand would be a good choice. There are also companies like www.hificollective.co.uk/ that specialise in Audio grade components.

@@AudioAmplifierServicing nice shop! Thanks for the link

Hi also remove the brown glue and check for dry solder joints.

Hi No, you need to install the correct rated fuse.

@@AudioAmplifierServicing Is it F 5.0 A 6x 32mm or 5x 20 mm? thank you very much

@@martin8134 Hi 5 x 20mm

Hi a common issue is the failure of the volume control potentiometer. So first check if you have Audio entering and exiting the Volume control circuit board for the faulty channel.

@@AudioAmplifierServicing Thank you! Would cleaning it help?

​@user-lf8dq2bf6r No the carbon track of the potentiometer fails.

@@AudioAmplifierServicing damn! Any idea where to source parts?

@user-lf8dq2bf6r From here fixpart.co.uk/product/sound-united-00d9430197305-potentiometer-focus-volume-amplifier but you need to confirm the potentiometer is faulty.

Hi see this tutorial for the fault your describing ua-cam.com/video/IHnEyu5pvDg/v-deo.html

@@AudioAmplifierServicing thank you very much

@@jrworpjrworp7254 Your welcome

Hi no it would not be possible

Hola Primero verifique los voltajes de la fuente de alimentación, puede descargar el manual de servicio desde aquí. elektrotanya.com/pioneer_a-103_a-203.pdf/download.html

Muchas gracias

Kevin, it's great to hear you have repaired the unit, and thank you for sharing your experience on the channel.