Member Since 02 Dec 2004
Offline Last Active Feb 09 2016 08:58 AM

Posts I've Made

In Topic: UPS Size for ComTech 8150 and CDi4000

08 February 2016 - 10:24 AM

CDI4000 : 1600W(x2) per ch @ 2 ohms, 3200W Bridge @ 4 ohms;
CT8150 : 1000W total, 125W per ch x8 @ 4/8 ohms;
For these two amps, I would select a UPS with 4200W available, make it 5000W for some extra headroom. That's still a very big UPS! I'm not sure if this requirement is available.
However, I doubt you'll ever be using the maximum full power available!
Note : UPS is used in computer systems to hold some power for a few minutes while you shutdown the computers. I wouldn't use a UPS to power a sound system while electricity is going off!
Why do you need a UPS for amplifiers?
Note : Current = Power/Voltage : 4200W/220V = 20A!



In Topic: Micro Tech 1200 "Supply" vs. "ODEP" LEDs?

27 January 2016 - 09:18 AM

Wow! Welcome back! :-)
I accept the fact that Supply is printed on the face plate. Since we've never seen this 'version', it doesn't mean that it didn't exist. However, some components, like main boards, may have the Crown copyright or p/n inscribed or printed on the material.
Do you have any technical expertise with these amplifiers?
Can you determine if the parts are genuine Crown parts?

In Topic: Help with vz5002 problem

21 January 2016 - 03:51 PM

Perhaps also verify the bi-level switch modules and the fet switches.
On the output modules verify the low value resistors, such as the 4.7 and 8.4 ohm bias resistors and the 22 ohms flame proof and the emitter resistors.


In Topic: Help with vz5002 problem

20 January 2016 - 10:31 AM

You can further your expertise : Since you swapped channels and the faulty channel followed, then it makes sense that the fault may be with the determined faulty channel.
Identify the two cards per module : from the top, identify and mark the two top cards Ch1 T and Ch2 T, then mark the two bottom cards, Ch1B and Ch2 B. Since one of the cards may be defective, then it is just a matter of determining which card is : For example, the problem is with Ch1; B or T? Remove Ch2 and swap T cards. If the problem is still with Ch1 then it has to be on the card which hasn't been swapped!

When power issues are determined, I usually check (if it hasn't been done yet!) the solder connections on the power devices. I have seen numerous times faulty solder connections on output devices. Repair these connections first.

Also verify the speaker distribution card : This card is attached to the speaker connections at the rear. This distribution board accepts two pairs of flat cables from the amp modules. Sometimes, the flat flex cable can break at the solder connection. This may not be relevant to this repair, just preventive.

I hope this helps!


In Topic: Crown XS4300 hum

20 January 2016 - 10:17 AM

Sorry for the delays, Mike, holidays were long! :)
Hum is usually caused by issues with the power supply. Verify and measure all filter caps.
Also, you mention that it can be intermittent : Perhaps bad solder connections at the power supply components leads?