Problem with Parasound amp

[jwhitakr]

Hey fellas (and ladies) - I could sure use some help on what to do with a Parasound HCA-800II amp that is giving me all kinds of problems with the left channel.

I bought the amp used, and it worked fine when I received it and for about the first week of use. Then last week, while I was messing with the settings and trying to calibrate the volume level to match my other speakers, I touched the gain knob on the front and got a nasty static shock. It was my fault since I was wearing socks and not paying attention to make sure I grounded myself before touching any of the electronics (grrrrr) ... and ever since then the left channel works only intermittently. :(

I'll turn on all my AV equipment, and it will play fine for 2-3 mins. Then it will start cutting out and stop working completely. If I turn everything off and on again, it still doesn't work at all.

I have eliminated the possibility that it is an issue with my pre/pro (using an HK AVR 235) or an issue with ICs/wiring. I swapped one of my Audiosource 100 amps for the Parasound, and it works flawlessly. I've listened to two CDs and watched about 20 mins. of a movie with no issues using the Audiosource amp, so I don't see any possibility of it being an issue of some other component.

I called the local Parasound service shop and they said it'd be $50 just to take a look at it. Assuming that they can find the problem and get it fixed, I am sure it'd be another $50 for parts / labor to get it fixed. Plus, there's no guarantee that they won't be able to find the issue or that it won't be another $100 or more to fix it. Considering that it only cost $150 used, I don't see the point in spending that much to get it fixed.

At this point I'm not sure whether to pay the $50 to have it looked at, or just chalk it up as a bad experience and look for another 2-ch amp. Anyone have any suggestions on what to do? Any thing I could try on my own to fix it? I'm by no means a handy-man, but I could open it up to take a look ... if I had any idea of what to look for.

[dkg999]

I think the static shock is coincidental to the problem. Most likely the gain adjustment hadn't been used for a long time and is causing the problem. Try rotating the gain knob back and forth repeatedly and see if the problem goes away. Cleaning the gain control with DeOxit is probably a good idea if you are comfortable doing it.

[vonnie123]

check the input jack for the left channel to ensure it is not mechanically damaged. It also might be a thermal sensor, since you indicate it works at start up, but fails after it warms up.

[jwhitakr]

Thanks dkg999 and vonnie123 for the suggestions! I will double check both the gain knob, and the input jack for the left channel, tonight when I get home.

If it is an issue with the thermal sensor, is there any way to test it or validate that as the issue?

[vonnie123]

Not sure if you could meter it or not. check with the factory tech staff. Most of the good companies tech staff are willing to help out...if you can isolate the sensor and compare one side to another, you might be able to garner some useful data. be careful not to zap yourself. I wish you luck in tracking it down.

[jwhitakr]

Well, I fiddled around with the gain knob last night and that did not seem to have any relation to the issue. When the amp cuts out, turning the gain knob up or down for the left channel has no impact. And when the amp cuts out it happens regardless of whether or not I have touched the gain knob.

I couldn't see any specific damage to the input jack for the left channel ... it was dark and I did not unplug everything to move the amp into better light, so there might be something wrong with the input jack that I couldn't see. I will unplug it and remove it from my HT stand to see if I see anything under better lighting conditions.

For the possibility of it being a thermal sensor issue, I'm afraid that's out of my range of expertise ... I'll plan to call Parasound tech support in the near future to see if they can provide any help. I tried calling them last week, but haven't been able to reach them yet during their office hours.

Thanks again for the help dkg and vonnie... if anyone else has any ideas / comments about what I should do, I'd definitely appreciate it!

[jwhitakr]

I have not been able to get a hold of Parasound tech support, since their hours do not exactly coincide with the time I am at home and can call them.

I opened 'er up and took some pics, and the only thing that looks weird to me (like I know what would look weird and what is normal!) is some blue goop that can be seen here:

http://i14.photobucket.com/albums/a313/jwhitakr/IMG_1751.jpg?t=1202444040

Here are the other pics I took ...

Gain knobs from the inside:
http://i14.photobucket.com/albums/a313/jwhitakr/IMG_1747.jpg?t=1202444263

L/R input jacks:
http://i14.photobucket.com/albums/a313/jwhitakr/IMG_1742.jpg?t=1202444337

Top view:
http://i14.photobucket.com/albums/a313/jwhitakr/IMG_1745.jpg?t=1202444384

Any ideas about the blue goop?

[vonnie123]

Not sure what that goop is. was there any residual on the interior of the case on top where it vents? will the material clean up or is it baked on? the service tech is probably the best bet with regard to your sanity. finding a needle in a haystack is just that sometimes.

[ben62670]

Loctite

[ben62670]

Does it get hot on one side, or does it turn off too quickly?

Edit
Be very careful with big caps like that. They can store electricity for a long time after being turned off. Check with a MM before sticking your fingers in there!!!

[jwhitakr]

Thanks guys for the info. There was no residual on the top of the case where it vents ... it was a bit dusty (as were other parts on the interior), but other than that it was clean as a whistle.

The amp has not gotten hot during the times I've used it, but I have not specifically checked one side vs. the other side to see if there is any difference in temperature. I will give that a shot this weekend to see if there is any difference from the left vs. right side.

Ben - I made sure that the amp was turned off for 48 hours before opening it up ... I've read about caps storing charges for a while after turning it off - I think it may have been from one of your posts, actually. Thank you for the warning. :)

I will do my best to get a hold of Parasound tech support in the next few days ... we'll see if they can offer any help.

[bikezappa]

You could have a loose or intermittent RCA input connection. Try wiggling it at low volume to see if the sound comes back on during wiggling.

[ShinAce]

Sounds like the signal before it gets to the amp. Check the input jacks and volume knobs carefully. You might want to use a jumper cable on the volume knob to bypass it temporarily.

You can make caps safe by shorting them out with a screwdriver before touching it.

[jakelm]

The blue goop looks like manufactures goop that tells the manufacture if the transformer has been tampered with.. ie unscrewed...

[jwhitakr]

Well, I finally took it into the repair shop ... and a week later my wallet is $85 lighter, but I have a fully functional amp! :)

The repair guy said that a few of the internal connections (can't remember exactly the word he used) had corroded and needed to be replaced. He also said he cleaned the connections very thoroughly.

It sounds great and I'm a happy camper. I can definitely tell the difference between the Parasound and the previous Audiosource amp I was using ... it's a tangible step up in sound quality.

[cfrizz]

Glad you're back in business!!!

[danger boy]

how long did it take them do turn it around? good work....

[jwhitakr]

Thanks cfrizz and danger boy... It took him just over a week to get it fixed and to test it to make sure the cutting in / out wasn't happening any more. I'm sure he was working on others at the time, too.

He also advised me to "switch out the patch cables" just in case they had gone bad, which seemed like odd advice. I told him I'd tested everything before I brought the amp in, just to make sure the problem wasn't with the cables or with the pre/pro, and he said he thought it'd still be a good idea. :confused:

Anyway, I'm happy with my Audioquest ICs and I'll just stick with the same set until something goes wrong.