Yamaha CA-1010 Project

langston

Active Member
Received this afternoon.

Needs meter lamps, power lamp, also power switch cover. Where could I acquire these?
 

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Acquired this CA-1010 from EBay. Unit was listed Repair/parts. The exterior looked pretty good excluding missing switch cover.

Once received popped the boot, found the interior pretty clean, appears it has never been worked on. No bulging caps, burn marks etcetera. There was some dust about not much.

Applied power relay clicks. No smoke or unpleasant scents.
Meter, power lamps out.
Turned unit off.

Started with basic maintenance.
Using canned air, ivory-dawn soap, soft brushes, swabs-cotton pads, a little 91% isopropyl alcohol. The interior, exterior; knobs cleaned up well.

Moved on cleaning rotary switches, RCA inputs, potentiometer using Electrosolve, Nu-trol.

Applied power relay clicks

Using headphones a mp3 device. I receive sound from left-right channel without static or drop-outs

Checked DC-Offset from speaker terminal-A Left channel produce -27.8 terminal-A Right channel produced -05.8. Input selector set at aux. (Ten minute warm-up/stabilization period)

Used a speaker set of zero value fired it up, played a few songs all seems fine; The speakers survived.

My questions:

Who to contact regarding power, meter lamps?

What other recommendations apart from basic cleaning?
 
I think member dgwojo is the lamp guru here (I may be slightly off- it could be djwojo or similar...)
 
DC offset should be zero'd after adjustment unless it doesn't have adjustment then there will be an acceptable range.
 
That unit only has a bias adjustment, no DC adjustment.
Did you adjust it? You're reading were in mV I hope :)
 
That unit only has a bias adjustment, no DC adjustment.
Did you adjust it? You're reading were in mV I hope :)

No I did not tamper with bias adjustment. I tested amplifier offset in stock configuration.

A Fluke 8024 B meter set at 200mv was used.
 
Cool-hifiengine has the manual, set the bias, let it warm up for 20 mins and retest. Then check the offset again to see if it comes down.
 
Cool-hifiengine has the manual, set the bias, let it warm up for 20 mins and retest. Then check the offset again to see if it comes down.

The service manual image stipulates connecting a 8 ohm 100 watt dummy load, When adjusting the bias, however. The text above the image stipulates 8ohm no wattage.

Can the bias be check without a load or alternative load?
 
I'm not sure why it needs a load, i've never had to connect a load to set bias before. May have something to do with class a/b operation.
 
Power indicator should be a red lens LED. Schematics should have the value. Probably 5V.

I've just used a Dremel to whittle one down to fit and glue it in place of the old one.
 
I had to replace the power led on my cr2020, I bought the fm am led board out of an 800 from eBay-im a little anal when it comes to restoring back to factory.
 
After a some hours. Here is what came about.

Amp set in normal operation.

Left board black lead tp1 red lead tp2 levels off 25.5mV with minimal adjustment.

Right board black lead tp1 red lead tp2 levels off 25.4mV with minimal adjustment.

Amp turned off set switch at class-a

Amp set at class-a operation.
Left board black lead tp1 red lead tp2 levels off 280.6mV with minimal adjustment.

Right board black lead tp1 red lead tp2 levels off 281.6mV with minimal adjustment.

Set amp in normal operation.

Re-checked DC-Offset from speaker terminal-A Left channel produce -27.1 terminal-A Right channel produced -05.2. Input selector set at tape1. (Amp had been operating for over three hours when this test was done)
 
After a some hours. Here is what came about.

Amp set in normal operation.

Left board black lead tp1 red lead tp2 levels off 25.5mV with minimal adjustment.

Right board black lead tp1 red lead tp2 levels off 25.4mV with minimal adjustment.

Amp turned off set switch at class-a

Amp set at class-a operation.
Left board black lead tp1 red lead tp2 levels off 280.6mV with minimal adjustment.

Right board black lead tp1 red lead tp2 levels off 281.6mV with minimal adjustment.

Set amp in normal operation.

Re-checked DC-Offset from speaker terminal-A Left channel produce -27.1 terminal-A Right channel produced -05.2. Input selector set at tape1. (Amp had been operating for over three hours when this test was done)

27 mv isn't really that bad.And shouldn't pose any audible problems.To get it any lower would require replacement of components in the inflicted channels front end ie. differential amp pair.

TR301 and TR302 would need to be replaced with and Hfe matched pair of 2SA872's or suitable sub.
 
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27 mv isn't really that bad.And shouldn't pose any audible problems.To get it any lower would require replacement of components in the inflicted channels front end ie. differential amp pair.

TR301 and TR302 would need to be replaced with and Hfe matched pair of 2SA872's or suitable sub.

You are correct, there aren't any audible problems.

Reviewing EchoWars DC-Offset thread appears the amplifier is still operating at a respectable range.

Wanting the amplifier changes keep at a minimum, I've been writing a to-do list for this amplifier.

I shall add possible replacement of TR301-TR302, and possible replacement pair of 2SA872's (Hfe matched).

Thanks avionic, bktheking, brutal.
 
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