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Electronics => Repair => Topic started by: eamondo2 on January 31, 2019, 10:05:00 pm

Title: Long shot - Phillips AV1002 amplifier Schematics
Post by: eamondo2 on January 31, 2019, 10:05:00 pm
First time posting here so forgive potential submission errors (I will endeavor to fix any missing required information as I know about it). I have a Phillips AV1002 amplifier, and am incapable of finding a service manual for making a repair. The issue lies in the input sub-board, two resistors have burned completely out, to the point that I cannot read their values, and a trace on the backside of the board itself appears to have exploded or burnt out as well. I am skilled with general electronics repair, and can figure out how to best replace and repair the issues, but am stumped as to what value resistors I need to replace.

If anyone knows where I can look to find a service manual, or has one, or can send me some photos of the board in question, it would be most appreciated. I've done as much digging as I can think to do, none of my usual sources for service/repair manuals have yielded any fruit. I've done about as much investigation of the board itself, and sadly the components don't seem to be mirrored in any capacity so I cannot figure how to infer the values based on the surrounding circuit itself.

The resistors in question are marked as "RED1" and "RED2" on the board in silkscreen, and aside from one other bulged capacitor nothing else has tested or appeared damaged so far. The board itself is marked as "PE01", with what appears to be a serial number of "YK055J163-3".

Attached to this post are photos of the board in question, I had to turn the compression up some to get past the attach size limitations but I can send higher-quality original photos if necessary.

Thank you for any and all help, it is much appreciated.

Regards
Title: Re: Long shot - Phillips AV1002 amplifier Schematics
Post by: fzabkar on January 31, 2019, 11:20:06 pm
I can't help with a service manual, but the photos at the following URL might help others to identify the unit:

http://www.hifido.co.jp/sold/15-88685-60515-00.html (http://www.hifido.co.jp/sold/15-88685-60515-00.html)

FWIW, according to a Dutch audio forum, the Philips AV1001 is equivalent to the Marantz AV-95C. Maybe the AV1002 also has a Marantz equivalent?
Title: Re: Long shot - Phillips AV1002 amplifier Schematics
Post by: The Soulman on January 31, 2019, 11:32:51 pm
What happened to have cause this destruction?
The op amp looks unhappy as well as one of the coupling caps.
Resistor values can be measured from the other intact inputs, looks three times the same to me.
Title: Re: Long shot - Phillips AV1002 amplifier Schematics
Post by: Chris56000 on January 31, 2019, 11:38:26 pm
Hi!

I found one site claiming to sell the AV–95C service manual but attempting to purchase it simply went to an "under construction" dead page!

Don't worry, you don't have to scratch your head any longer as it's simply two pairs of identical channels, the resistors burnt out are the same value as those that arent, i.e., RE01=RE02=RE03=RE04, and all four of them are 1k0 ⅛W apiece!

However I would also recommend replacing QE01 & QE02 (NE5532) as a precaution, as their inputs could well have been damaged by the overload that burnt out the series I/P resistors!

(The one most badly burnt, RE02, goes to pin 5 or QE01, which is the + or non–inverting input of the 2nd amp in the package!

Good luck!

Chris Williams
Title: Re: Long shot - Phillips AV1002 amplifier Schematics
Post by: schmitt trigger on January 31, 2019, 11:47:00 pm
You know it is an old piece of equipment, when the board components are labeled "Japan".

Nowadays they are "China".
Title: Re: Long shot - Phillips AV1002 amplifier Schematics
Post by: fzabkar on February 01, 2019, 12:26:23 am
The bulging cap appears to be at the input of the bad channel, ie a coupling capacitor. The lifted traces are at the output of the same channel. ISTM that the damage is consistent with the application of AC power to the bad channel, or perhaps a lightning strike on the cable run (???).
Title: Re: Long shot - Phillips AV1002 amplifier Schematics
Post by: ElecSeb on February 01, 2019, 12:54:16 pm
I always like to see structures on boards, in this case it seems quite easy:
3 channels, all showing the same build-up.

RE11=RE12=RE09=RE10=RE07=RE08
RE01=RE02=RE03=RE04=Re05=RE06

QE01=QE2=QE03
CE21=CE22=CE23

Etc, 3 channels, same components per channel.
Cannot see the screen well enough to give more examples.

Furthermore on this forum are some Philips enthusiast:
https://www.circuitsonline.net (https://www.circuitsonline.net)

Be aware Dutch forum, but you can ask in English!

Title: Re: Long shot - Phillips AV1002 amplifier Schematics
Post by: eamondo2 on February 01, 2019, 11:18:18 pm
Thank you all so much for your help, I'd been working on drawing up a schematic to see if I could find some similarities like you all have mentioned. I will check to see if the values from the non-damaged sections match the patterns, and work on getting her patched up.

As far as what the source of the damage could be, I honestly have no real clues, it is especially puzzling as this board is the input side of the amp itself, it holds the 3 stereo RCA connectors. Not sure how what I am assuming to be a surge of some sort would have blown these resistors that badly. There appears to be a trace on the backside of the board itself that has exploded or been horribly mangled in some way, but I will be testing all the other components with a fine-toothed comb to make sure I don't have any surprises waiting.

I have a frustratingly minimal amount of information on the problem and how it arose, the person I got it from could tell me nothing, and apparently it's been a while since it was ever attempted to be used.

Thanks again to all who have offered suggestions, I'll post soon with some results!