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Post by JojoD818 on Jan 25, 2005 17:15:13 GMT 7
Of all the gears I have restored, this is the first time I ever documented such a job. Anyway, our specimen is a Kenwood KA-87 integrated power amp owned by a friend from another forum. Though replacement of caps and such are what most of us do, this one just needs some reforming (in-circuit) and a much needed bubble bath. ;D I intentionally didn't took any pic of the amp while being sprayed with highly volatile chemicals, like what they say, don't try this at home.... ;D ;D The amp being given an air job and a vacuum prior to a bath. ;D ;D
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Post by JojoD818 on Jan 25, 2005 17:16:14 GMT 7
This is after the whole amp is took a bath... Refreshing indeed!
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Post by JojoD818 on Jan 25, 2005 17:17:18 GMT 7
Another air job to fully dry this beauty...
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Post by JojoD818 on Jan 25, 2005 17:19:10 GMT 7
Once fully dried, it's off to adjustments. BTW, found some oscillation on the left channel but after a bias rework, both channels are running fine at 40mA idle current per channel.
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Post by JojoD818 on Jan 25, 2005 17:21:53 GMT 7
The amp was almost taken apart to reach those stubborn dust and most off all the switches that needed cleaning and lubrication. The front panel switch assembly is in fact behind this plastic faceplate. The entire front cover was given a soap treatment and a special polish to highlight the labels and its black brushed styling.
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Post by JojoD818 on Jan 25, 2005 17:22:32 GMT 7
Adjustment ala king...
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Post by JojoD818 on Jan 25, 2005 17:23:24 GMT 7
The amp came without a volume knob, lucky thing my friend went to Manila to buy some parts. ;D
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Post by JojoD818 on Jan 25, 2005 17:25:31 GMT 7
Testing 1 2 3...... Since it's integrated, I tested the amp with a tube preamp working as a buffer through the amp's Tape 2 monitor switch... Voila! Listening tests and probably some adjustments and this amp is off singing again!
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Post by sandawa on Jan 25, 2005 17:30:18 GMT 7
interesado ako rito. nakalimutan ko i-konsulta sa 'yo two weeks ago. last november, pinaliguan ko yung luma kong Kenwood Receiver (KR-7400) using water spray gun and after a while, brought it to the nearest gasoline station for an air spray para tanggal lahat ang dumi sa loob. i used WD-40 on the usual devices and i always do this process every five years for my amps.
ang problema ko, sa case ng Kenwood Receiver, nawala yung FM although the AM is working. the amp section is also okay. ano kaya 'to may natanggal lang? i checked the usual cable connections, including the FM antenna, okay naman. saan kaya ako nagkamali?
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Post by JojoD818 on Jan 25, 2005 17:37:21 GMT 7
interesado ako rito. nakalimutan ko i-konsulta sa 'yo two weeks ago. last november, pinaliguan ko yung luma kong Kenwood Receiver (KR-7400) using water spray gun and after a while, brought it to the nearest gasoline station for an air spray para tanggal lahat ang dumi sa loob. i used WD-40 on the usual devices and i always do this process every five years for my amps. ang problema ko, sa case ng Kenwood Receiver, nawala yung FM although the AM is working. the amp section is also okay. ano kaya 'to may natanggal lang? i checked the usual cable connections, including the FM antenna, okay naman. saan kaya ako nagkamali? Check the IF stages of the tuner section, there should be separate sections for the AM and FM if it's not an IC type tuner. If it still has a metal tuning capacitor, make sure it didn't had any corrosion due to the bath. Or maybe the air pressure of the air job misaligned one of the IF or tuning caps. I don't use water for audio gear baths, I make a special mixture of volatile liquids and solvents for this solution. The end result is a highly volatile solution that is as good as water in cleaning but does not promote oxidation and evaporates fast.
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Post by kimpao on Jan 25, 2005 17:44:06 GMT 7
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Post by iceman90a on Jan 25, 2005 17:47:32 GMT 7
Very Nice Doc J! matutuwa si ... nyan (kanya yan di ba?) hahatid mo ba o pick-up nya?
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Post by audioslave on Jan 25, 2005 17:52:19 GMT 7
I don't use water for audio gear baths, I make a special mixture of volatile liquids and solvents for this solution. The end result is a highly volatile solution that is as good as water in cleaning but does not promote oxidation and evaporates fast. JojoD, if you don't use water to dowse the amp or any electronic gadgetry for that matter, what solutions or mixture of volatile liquids did you used?
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Post by sandawa on Jan 25, 2005 17:54:14 GMT 7
Check the IF stages of the tuner section, there should be separate sections for the AM and FM if it's not an IC type tuner. If it still has a metal tuning capacitor, make sure it didn't had any corrosion due to the bath. Or maybe the air pressure of the air job misaligned one of the IF or tuning caps... thanks, kaya ko na 'to. galing mo talaga sir.
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s2kov
Critical Listener
Posts: 353
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Post by s2kov on Jan 25, 2005 18:04:12 GMT 7
you can use lacquer thinner for cleaning solution! dapat madaling matuyo kapag nahanginan! ;D
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Post by JojoD818 on Jan 25, 2005 18:39:24 GMT 7
you can use lacquer thinner for cleaning solution! dapat madaling matuyo kapag nahanginan! ;D hala ka! very risky yan sir ;D ;D ;D, lacquer can damage the board's solder mask and protective sleeve. i did tried that before kasi kaya nasubukan ko na makasira. ;D ;D ;D under controlled circumstances pwede siguro pero ingat lang baka magaya sa VU meter cover nung amp ni boss akyat yun mga plastic parts nun amp!
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Post by JojoD818 on Jan 25, 2005 18:41:53 GMT 7
Very Nice Doc J! matutuwa si ... nyan (kanya yan di ba?) hahatid mo ba o pick-up nya? yup bro sa kanya yan, I invited him here sa forum. Probably meet na lang, patay ako sa byahe ko. ;D ;D
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Post by JojoD818 on Jan 25, 2005 18:45:54 GMT 7
JojoD, if you don't use water to dowse the amp or any electronic gadgetry for that matter, what solutions or mixture of volatile liquids did you used? I use a mixture of Ethylene Glycol, Meathanol, 85% IPA, Kerosene, Unleaded Gasoline, 250cps Silicone Emulsion, and other oil-based derivatives. Not for the faint-hearted though.
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Post by JojoD818 on Jan 25, 2005 18:47:30 GMT 7
Oh I forgot, add some Glycerine too for that shiny look on the parts.
JojoD
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Post by iceman90a on Jan 25, 2005 18:47:31 GMT 7
yup bro sa kanya yan, I invited him here sa forum. Probably meet na lang, patay ako sa byahe ko. ;D ;D sa may pioneer st lang naman work nya kaya madali kayo makapag set ng meeting sent you pm
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