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Old 08-27-2019, 02:05 PM   #1
meciu
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Default TEAC AG-D8550 no sound on speakers

Hey guys!
Maybe someone will help me with my problem.

I was testing new speaker till there was 'pop, bang & smoke' inside..

found shorted:
-diode D127 mainboard - replaced
-power transistors Q205FR Q206FR AMP board - replaced with equivalent MN2488 + MP1620 (did the same for the FL channel)
-resistor R218FR AMP board - replaced

now device is turning on without any problem, headphones output is working fine, but question is - why I don't get any sound on speakers?



In attachment service manual for almost the same device (main, amp and st-by board are the same)
Attached Files
File Type: pdf sherwood_rd-6502.pdf (4.01 MB, 2 views)

Last edited by meciu; 08-27-2019 at 02:15 PM..
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Old 08-27-2019, 03:31 PM   #2
R_J
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Default Re: TEAC AG-D8550 no sound on speakers

Check the voltage on TP201FR pin3, it should be near 0 volts, if it is not I suspect the amp is in protection. Check this test point on all amp sections.
Did you also check the 0R22 emitter resistors?
If R218 was open, Q204FR may also have been damaged

Last edited by R_J; 08-27-2019 at 03:39 PM..
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Old 08-27-2019, 06:25 PM   #3
CapLeaker
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Default Re: TEAC AG-D8550 no sound on speakers

also make sure there isn't anything stuck in the headphone jack.
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Old 09-11-2019, 01:36 PM   #4
meciu
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Default Re: TEAC AG-D8550 no sound on speakers

So yeah, found burned 0R22 emitter resistors; replaced them and it started to work!

Thanks guys!
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Old 09-11-2019, 02:33 PM   #5
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Default Re: TEAC AG-D8550 no sound on speakers

always check emitter resistors after blown outputs or just replace as they can fail later on as been stressed .
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