JVC TH-C30 Home Theatre

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Randy
JVC TH-C30 Home Theatre

I have a jvc home theatre with a power subwoofer. When I turn on the unit my sub doesn't power on. I've replaced the sub and it doesn't power on either. the only component in the main unit that looks like it may have got hot (browning around pins on chipboard may be normal) is a 5 pin piece which looks like a transistor marked STRG6651 what is this and could it be a problem? If not what else could be wrong?

Larry Dillon
That part is a regulator IC. 

That part is a regulator IC.  The data sheet is HERE.

Randy
Thanks for the info. Larry. I

Thanks for the info. Larry. I'm a rookie at electronics and am just starting out in a course and so far don't know a whole lot. I was wondering if it's possible that this could regulate the current or act as a divider to turn on my power sub through the main unit? I have no idea how to test this IC but do you think this theory might work?

Larry Dillon
nope. This IC is for the

nope. This IC is for the regulation of the power supply. If you tryed another unit and the replacement unit did not work, I would look into the connections on the main unit and on the sub. Something is telling the unit not to switch on. Has it ever worked? Make sure the audio leads are connected to an output on the main unit. Arte there any other connection to the subs beside the audio leads and the power cord?

Randy
Thanks Larry. Yes the unit

Thanks Larry. Yes the unit did work fine. I assumed buying a new sub would work and didn't. The only connections are 1 special cable from the main unit to the sub, it's similar to s video cable but is a special JVC cable with about 8 pins in each end, and all speaker wires run off the back of the sub and then the sub has it's power cord. There are no audio cables on the back of the main unit.

Larry Dillon
Ok so the sense on line and

Ok so the sense on line and the audio is in the connection wire. I would say there is a problem in the main amp unit if you already had a known working sub there. Let me ask if Dan knows anything about this unit your talking about.

Randy
The only other thing I did

The only other thing I did try was doing a continuity test from pin to pin on each end of the cable from the sub to the main player to see if maybe the cable had an internal break and everything seemed fine. Thanks for your help Larry I appreciate this.

dans_repair_service
I'm not familiar with this

I'm not familiar with this specific model, so a few questions are in order...  1.  Do you plug in the sub-woofer (into the walll for AC?)  2.  Do all of the functions work on the main unit? 

Some speculation here:  I believe that the original sub had a problem which caused a porion of the main unit to also fail.  This would account for the replacement not working.  Many of these types of systems utilize the main amp for control and signal processing.  Along with the regulator being fried, the control circuits are most likely smoked as well.  I'll attempt to get the service manual for this unit and post additional details. (Note: this will take a few days)

Dan

Randy
Thanks so much Dan. Yes the

Thanks so much Dan. Yes the sub does plug in AC and the main unit does work eg. discs spin  lcd shows functions and if you plug headphones into the main unit everything works fine through headphones. Just nothing to the sub and therefore no speakers.

dans_repair_service
Without the service manual, I

Without the service manual, I'll go out on a limb here (hopefull one close to the ground...)  The sub-woofer most likely takes line output and pulls out the low frequencies.  These are then processed and amplified locallyfor both the main speakers and sub.  Whatever the problem was within the original sub, most likely fried the preamp section or the control section in the main unit.  Headphone level is usually achieved using a small IC amp for this type of setup.  The repair of this will require the service manual.  I'll check with my JVC service center contact and attempt to get one during the week.

Dan

Randy
Thanks Dan, I really

Thanks Dan, I really appreciate the help.

Randy
Well Larry you're right  but

Well Larry you're right  but I couldn't have got the help without you, so you're the man too. Thanks so much guys!! I appreciate it!

Larry Dillon
No problem! Thats what

No problem! Thats what techlore.com is all about!

 

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