Help New Guy (Rockville RXA T1 Car Amp)

Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
Do this again but do each channel twice. Check then reverse the probes and re-check.

Interesting Results

Channel 1 (test 1 & 2) beeps, numbers flash eventually land on 469 ohms
Channel 1 (test 3) reversed leads beeps, numbers flash eventually end on 468 ohms

Channel 2 (test 1 & 2) 1320 ohms
Channel 2 (test 3) reversed leads OL

I also tested 3 open transistor resistors in the output section channel 1.
 
Last edited:
Do any of the output transistors read as shorted or leaking?

Yes sir - 3 of the 4 channel 1 output transistors tests shorted with my MM in circuit across C & E. These are the same 3 with open resistors.

I've forgotten how to test for leaks with a MM but i suspect it's a matter of reversing the leads across Base & Emitter? Is that correct?

Another stupid question where a good source to purchase a variety of 1/2 watt resistor values commonly used in car amps? I used to just drop by the local radio shack but they've closed so many of their brick and mortar stores, I don't have one near me any more.
 
Last edited:
To check for leakage, you use 'ohms' and check all combinations both ways. The meter should only react in one direction.

Mouser and digikey are good sources for anything you need for repair.

Perry thanks for taking time with me on this - I really do appreciate you. One last question if I may while I wait for parts to arrive.

My thoughts about how to approach this repair / rebuild is to work from the DC source in to the other side. So first is making sure the power supply circuitry is up and operational, then the rectifer circuity, next would be the output, then finally the ac input (RCA) back in to the output.

If I recall correctly... the power supply should produce a nice flat pos and neg voltage. What the voltage is I'm not sure but both voltages should be mirrors over each other (pos & neg) is that correct? These voltages feeds the rectifer. The rectifer then flips the neg to pos to establish the rail voltages that in turn feed the output section?

Like I said it's been so long (mid 80's) since I learned about this stuff and it's really kind of sad I've forgotten a lot of what I learned. That old saying if you don't use it you loose it is true for me.
 

Attachments

  • IMG_20171202_192445369.jpg
    IMG_20171202_192445369.jpg
    1,006.6 KB · Views: 86
They might be 2N6055C darlingtons, I can't imagine their use in an automotive amplifier claiming that power level. I can't imagine an automotive amp could produce that much power in a package of that size or cost.

References to YPI semiconductors appear on the web, I would not click the associated links as they appear bogus.

The amp costs about $70 retail so I would not spend much on an attempt to repair it.

Sorry Kevin i must have overlooked your response - sorry about that. Rockville car / marine amps are not bad. They are not the best out there but not the worst either. But for the price they are hard to beat. Most of their amps / speakers have three ratings Peak / RMS / CEA for various speaker loads.

For example this 1500 watt 2 channel has the following specs:

Rockville RXM-T1 1500 Watt Peak / 750 Watt RMS Marine 2 Channel Amplifier

CEA Compliant Power Ratings:
250 Watts (2 x 125 Watts) at 4 ohms and 1% THD+N
370 Watts (2 x 185 Watts) at 2 ohms < 1% THD
1 x 370 Watts bridged @ 4 Ohms < 1% THD

RMS Power Ratings:
750 Watts (2 x 375 Watts RMS) @ 2 ohms
1 x 750 Watts @ 4 ohm Bridged Mono
500 Watts (2 x 250 Watts RMS @ 4 ohms) < 1% THD

Peak Power:
1500 Watts (2 x 750 @ 2 ohms or 1 x 1500 @ 4 Ohms)

I always go by the CEA ratings for amps/speakers since it's the closest realistic rating you can get. Problem is a lot of manufacturers don't include CEA ratings for their gear.

BTW - I have Rockville's RXM-S6 Marine/Boat 6 Channel Amplifier bolted to the back wall behind the rear seat in my pickup. It's powering 12 8ohm door speakers, plus 2 dual 4ohm voice coil 10" subwoofers. If I get on it, it's so freaking loud it makes my eyes water, rattles my teeth and makes my nose itch. Not to say all mirrors are rendered useless. I really enjoy the clear A/B sound the RXM-6X produces and it's given me absolutely zero problems so far.

Have a look see -->Rockville RXM-S6 Marine/Boat 6 Channel Amplifier 2600 Watt Peak / 1300w RMS - Rockville Audio

Anyways I hope that helps???
 
Last edited:
Well I replaced channel 1 output transistors along with a few resistors. I also replaced all of the power supply transistors with IRF3205s. I then hooked it up to a 12v power supply with a 5watt fuse, did a little probing. I thought everything looked good... I even played it about 15 mins on the test bench.

I then reinstalled it back in my truck and after about 10 mins of playing the power supply bank burnt out :(

IMG_20180101_121540976.jpg

I know for sure I didn't have any solder bridges - now I'm lost on where to start over.
 
Last edited:
Well I replaced channel 1 output transistors along with a few resistors. I also replaced all of the power supply transistors with IRF3205s. I then hooked it up to a 12v power supply with a 5watt fuse, did a little probing. I thought everything looked good... I even played it about 15 mins on the test bench.

I then reinstalled it back in my truck and after about 10 mins of playing the power supply bank burnt out :(

View attachment 654089

I know for sure I didn't have any solder bridges - now I'm lost on where to start over.

I reattached the picture. I just replace all of channel 1 and both banks of power supply transistors. A few resistors we're also open and needed to be replaced.
 

Attachments

  • IMG_20180101_121540976.jpg
    IMG_20180101_121540976.jpg
    1 MB · Views: 71
Did you check them out of the board? It's very rare to see rectifiers fail in an amp like this.


MUR1620CTRG ON Semiconductor | Discrete Semiconductor Products | DigiKey

Hi Perry no not yet but I will... New symptom though I hope you can help me with. Even with the remote wire unhooked the negative side of the bank of 3 PS transistors heat up / snap / crackle / pop / burn up. They are IRF3205 with 47 ohm resistor on the gate. The positive side is fine.

I have not replace the two outputs yet A1266 - waiting for them to come in.

MUR1620CTG ON Semiconductor | Discrete Semiconductor Products | DigiKey
 
Last edited:
Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.