Panasonic SA-AK 22 volume failure - Page 1
Forum section: electronics / general

author: ByteMe
author_rank: Contributor
timestamp: June 05, 2013, 04:05:47 pm
content: So I've had this panasonic stereo for over 10 years and I'm very happy with it, but lately it's been collecting some dust. The volume slowly died on me: first I had to play with the button (service manual states that it's a variable resistor, but as it turns all the way around and I can also set the volume with the remote, I expect it to be either a non-stop pot or an optical encoder of some sort). Later, things got a little more ugly: I had to turn it of and on again a couple of times and sometimes even a tap on the side would help. But now, it just works fine altogether, but something just cuts off the output. Is there anyone out there who knows if this is a common problem? I've googled the hell out of it and tried opening the thing up and cleaning it out, but I found no obvious faults(I still suspect some kind of mechanical failure).edit: The headphone jack is dead too...

author: PeterG
author_rank: Frequent Contributor
timestamp: June 05, 2013, 05:47:42 pm
content: It sounds like the volume control pot has died. Having a remote control means it may be a motor driven type similar to this.http://www.altronics.com.au/index.asp?area=item&id=R2000Regards

author: ByteMe
author_rank: Contributor
timestamp: June 05, 2013, 06:29:22 pm
content: Forgot to mention: I'm getting fault codes H03 and F26 from the service manual(google it, it's out there somewhere, I just couldn't find a direct URL fast enough).I'll have a look if there's a motor driving the pot, but I don't remember there being a motor...Edit: I checked, there's definitely no motor on that pot, but it does seem like a pot to me. I remember trying to measure that sucker, but I got a whole lot of nothing, could that be from the caps(see service manual) right next to those points? Maybe I should desolder it and then measure. I just need to know how I can identify the problem as a bad pot.

author: ByteMe
author_rank: Contributor
timestamp: June 05, 2013, 07:52:01 pm
content: That 'pot' goes beep-silent-beep-silent-beep-silent-beep on the continuity with 1 and 2 and 2 and 3. It must be an encoder, but I don't get how it interacts with the circuit it's in(page 40 of the service manual) with the two caps. I get that 1 and 3 are in some kind of setup that makes a difference between turning left and turning right, but that really can't be the cause of my problem. I'm starting to suspect IC500, the power amp. I remember having another fault-code last time I opened it up, but I'm not certain, it may have been F61(which means I'm screwed, because that's a dead power amp...)

author: ByteMe
author_rank: Contributor
timestamp: June 05, 2013, 08:58:58 pm
content: Just inspected all the caps around the power amp, they don't look too bad a brand(sadly, no panasonic brand caps in my panasonic stereo) I can't see any burn marks or whatnot, just some thermal paste bulging out on top... Other models are fixed by cleaning the fan for the bloody thing, but sa ak22 doesn't have a fan and I can't remember giving it a proper thrashing. I never played that thing awfully loud, it doesn't make senseCould it really have died over the years? Are the near(I should say WAY TO CLOSELY PLACED) elco's dried out perhaps?

author: PeterG
author_rank: Frequent Contributor
timestamp: June 05, 2013, 09:58:18 pm
content: I looked online for the servuce manual but the sites want $$$ gor it. It sounds like its going to be a bad cap or dry joint somewhere. Great job for a rainy day.

author: David_AVD
author_rank: Super Contributor
timestamp: June 05, 2013, 10:45:02 pm
content: Check for dry / cracked solder joints first. PM your email address and I'll link you to a service manual for it.

author: ByteMe
author_rank: Contributor
timestamp: June 05, 2013, 10:51:33 pm
content: Just put the sucker all back together... How could I forget checking solder joints? Oh well, I'm pretty sure I did that last time and nothing stood out when I was looking for blown caps. That brings another question: how can I determine which cap has gonewith just a simple DMM(Amprobe XR34)

author: David_AVD
author_rank: Super Contributor
timestamp: June 05, 2013, 10:57:20 pm
content: Capacitors in something like that are usually pretty good. Check for ones that have vented or that may have been fried by being right next to a heatsink.So many faults in consumer gear can be put down to dirty pots/switches, cracked joints and oxidised connectors. Always check these basics before running off on tangents.

author: ByteMe
author_rank: Contributor
timestamp: June 06, 2013, 09:22:45 pm
content: Yeah, C517 is right next to that big ass power amp ic500, it' even a little bent over to the side. No vented caps though...

author: David_AVD
author_rank: Super Contributor
timestamp: June 06, 2013, 09:30:06 pm
content: Have you downloaded the manual yet?EDIT: I just saw your PM.

author: mzacharias
author_rank: Frequent Contributor
timestamp: June 07, 2013, 11:39:22 am
content: The website Elektrotanya has several free versions of this manual. One does have to register and pass a basic electronics competence test. Also, the site is Hungarian and can be difficult to navigate. The site can be (partially) switched to English.The rotary encoders are a common problem; Operation can be confirmed using a 'scope with reference to chassis ground. A defective one will obviously show noise as the control is rotated, generally on the center pin.With respect to the OP's other problem - yes, solder connections at the output IC and regulators are possible, as is a failing voltage regulator IC.Time to drag out the multimeter and start checking some voltages...