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Old 06-14-2018, 09:35 AM   #21
budm
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Default Re: Aiwa CA-P50, low power output

OK, so it not a complete unit, it is just a bunch of boards and some chassis.
So when you are testing this thing out, the boards are not mounted to any metal chassis that are not connected together, correct?
Some of these unit will not work properly if the boards are not mounted to the chassis because it uses the chassis for GND connection between boards.
Do you have the heatsinks too?
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Old 06-14-2018, 10:08 AM   #22
perette
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Default Re: Aiwa CA-P50, low power output

HI Budm

Sorry my english can be improved.

when I've discovered the two units they were complete.
I tested them and get the bad sound out of it.

Then I had to open the box to try to discover the root cause of the problem.

As you can see on the picture, the amp is a small format factor and accessing boards means removing all surrounding parts.

But I've not unsoldered any board. so ground is connected . When I've tested Voltages point my ground was on the main board and they were all in acceptable range.
so main board (the one with the big hole) has the two channels located on both side, the led signal panel is located on the front. only the back panel is not soldered (only screewed), but when testing, all cable were reconnected.

but maybe I've missed a point there.

Let me kow, I"m not an expert, but learing is always good.

Best regards

JM
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Old 06-16-2018, 05:29 AM   #23
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Default Re: Aiwa CA-P50, low power output

Perrete , come back to my first advice !
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Old 06-16-2018, 07:36 AM   #24
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Default Re: Aiwa CA-P50, low power output

Hi gentlemen

@piotr. Done the test
Cb1 and 2 are OK. 0 ohm resistance.
S4 looks OK. It closes.do I unsolder it or clean contacts?

Voltage on r51 and 52 close to zero.
R53 and 54 have been adjsuted as written in the manual 5mv. But the idling current cannot be adjusted on both channels.

I'll check other transistors now

Best regards.. Jm
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Old 06-16-2018, 08:04 AM   #25
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Default Re: Aiwa CA-P50, low power output

Hello again

Q7, 9, 11 and 13 and their counterparts on the other channels are OK.

So do I change the fusible resistors?

It look like 100 ohms 1/4w fuse resistors are not that easy to find. I had a loon at mouser and farnell, but not found them. Any recommendations if changing them is the try to make?

Best regards

Jm
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Old 06-18-2018, 02:01 AM   #26
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Default Re: Aiwa CA-P50, low power output

Hello everybody

I've googled a lot and the only option seems to use a 10 ohms 1.4W and add it a 90 ohms.
Nothing at Mouser, nor Franell, nor Digikey.

will it do the job ?

Best Regards

JM
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Old 06-21-2018, 06:45 AM   #27
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Default Re: Aiwa CA-P50, low power output

What resistor you need to replace ?? Is some 100ohm defected ?
Please try to write clearly and concretely .
If some 100 Ohm is defect, you can use normal type of resistor.
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Old 06-21-2018, 06:48 AM   #28
perette
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Default Re: Aiwa CA-P50, low power output

HI Piotr

thanks for the reply.

I Learn that my question was a bit "stupid".

a metal foil resistor 100 ohms 1/4W will do the job.
i ordered them and will change them.

i'll keep you posted of the result.

You've lall been of great help. I learned a lot on the process to analyse such failed apparatus and what "not to do".

Best regards

JM
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