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-   -   Orion HCCA 2100 no rail voltage. (https://www.diyaudio.com/forums/car-audio/335944-orion-hcca-2100-rail-voltage.html)

Chopperbuilder 29th March 2019 10:54 PM

Orion HCCA 2100 no rail voltage.
 
Working on an Orion HCCA 2100. It is not producing rail voltage. Pin 12 of the 494 is at +10.38v DC. I'm not that familiar with the layout of this amp, looking for some help fixing it.



I just replaced all the electrolytic capacitors, PS FET's, output transistors, MPSA06's and MPSA57's. Amp had a couple of blown PS FET's but did power up prior to me replacing those components.

Perry Babin 30th March 2019 04:23 AM

This amp and virtually all of these old amps use virtually identical circuits. The troubleshooting will be virtually identical to your other amps. You start by checking the voltage on all pins of the 494.

Chopperbuilder 30th March 2019 04:59 AM

I noted that with the circuits design of these amps. How the board is layed out is different between the models.

The 494 DC voltages:
1. +0.014
2. -0.002
3. -0.022
4. +4.87
5. +1.476
6. +3.390
7. -0.00
8. +10.71
9. +0.012
10.+0.022
11.+10.71
12.+10.71
13.+4.90
14.+4.90
15.-0.002
16.+0.013


Given that the circuits are basically identical...as with the HCCA 225 it looks to be that the voltage on pin 4 is way to high.

Perry Babin 30th March 2019 05:10 AM

Yes. 4 is too high. You can try to bring it down with the resistor between 4 and 7.

Chopperbuilder 30th March 2019 05:26 AM

A 10k resistor between pins 4 and 7 on the 494 only dropped the voltage down to +4.45v DC on pin 4

Perry Babin 30th March 2019 05:37 AM

Black probe on the main ground terminal/wire, what is the DC voltage on the RCA shields?

Chopperbuilder 30th March 2019 05:43 AM

With the black probe on the main ground terminal/wire, the DC voltage on the RCA shields is +12.11v.

Perry Babin 30th March 2019 05:48 AM

It appears that you either have a solder bridge or a shorted transformer.

Don't connect remote to the amp. Do you still have 12v on the shields?

If so, remove one fuse at a time to see which makes the DC on the shields go to 0v.

Chopperbuilder 30th March 2019 05:58 AM

With remote disconnected the voltage on the RCA shields was -0.00v. I then reconnected the remote and checked it again and it was still at -0.00v. Not sure why I got the +12.11v reading earlier but I'm thinking one of the speaker leads may have been touching the power connection on the remote wire.

Perry Babin 30th March 2019 06:01 AM

Now that you have no voltage on the shields, is pin 4 down to near 0v?


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