Crossfire VR2000D Repair issues

[Perry Babin]

http://www.mcminone.com/product.asp?...me=MCMProducts

Mouser will have the resistors and zener diodes. Order extras of each.

Did you check 'all' of the gate resistors on the outputs to make sure they were within tolerance?

Were the 2SC1027s (Q273 and Q283) OK?

[intensem1rider]

I checked every single resistor and focused on the ones were looking at and all but that one read 1 ohm.

I did check the Q273,Q283, I had a reading around 0.5 volts with the neg on the 3rd leg and pos on the middle (2nd leg), but nothing on the 1st leg, but I was testing those while in the board.

Is there a specific physical size/tolerance/power rating I should be looking for when it comes to the resistor, there seems to be many size variations available. it measures around 0.128" or 3.29mm long.

[Perry Babin]

If the resistor measures 0.128", it's either a 1206 (0.120" x 0.060") or a 1210 (0.120 x 0.100). Select whichever they are as the size when searching. From the photo, it appears that they may be 1210s. If you have a dial caliper, use that to measure them.

The tolerance isn't really important If the value on the originals is 1R0, it's a 5% component. Replace both of the 1 ohm resistors that were connected to the failed 2SA1023s.

If you read an open circuit on the 2SC1027s when you had the red lead on the 3rd leg and the black lead on the first leg, the transistor is defective. It should have read near 0.6v.

[intensem1rider]

I re-tested the 2SC1027s , I tested them backwards earlier, they are fine when I test them properly. Amazing how that works...

Im going to order about 6 of each transistor and about 10 resistors just to have them on hand. I already have the 12 volt Zener diodes lying around from a power supply project from school.

Anything else I should look into before ordering?

[Perry Babin]

I can't think of any other parts you'd need. Get the parts in it and power it up. Remember to have ALL of the power semiconductors clamped tightly to the sink when you power it up. If there is a problem, you can destroy lots of parts if the transistors are not clamped down. Have a 15 amp fuse in the B+ line when you power it up.

You may want to make sure that all of the insulators are intact. You should also order a tube of heatsink compound.

[intensem1rider]

ok, sounds good, I'll get back to you after power up next week.

[intensem1rider]

I received your amplifier repair dvd and now im looking to buy some broken amps off e-bay to work on over the year to gain knowledge while going through your dvd and such.

I have found some great deals on these amps below, what would you recommend I start with and stay away from since im a level 1/2 repairer I guess.

Rockford P450.2
Rockford RF2002
Rockford P250.2
Rockford Punch 501S
Rockford Punch 120.2
Hifonics BX2005D
Alpine MRP-M450
Alpine MRP-F250
Kenwood KAC-929
Bazooka ELA500.1

Of course im looking for the best turn around profit margin, I would like to sell them and in turn use that money to buy equipment such as an Oscilloscope and such.

[ppia600]

You would probably start at the bottom of the list and work your way up.

[Perry Babin]

The bazooka and the kenwood are probably going to be the easiest but they're probably not worth much.

I don't have much experience with the newer alpines but alpine sometimes uses relatively complex discrete circuits which can make troubleshooting difficult for those who are new to repair work. They do offer service manuals though which can make things easier (but is also an extra expense). In the newer amps, they epoxy the SMD components to the board so that can make it a bit more difficult to check/replace the components.

The class D Hifonics will probably be easy to repair if there isn't extensive damage to the driver board.

The punch amps are generally easy but you'll have to deal with SMD components and the MEHSA strips. Rockford also provides schematics for amps that are out of production.

Email me and I'll point you to relavent information on the disc.

[intensem1rider]

Well looks like that got the Crossfire working again. I have it completely put back together hooked up on the bench with a 2 ohm load getting tested right now, I have it on a 50 hz tone and it seems to be playing distortion free for the last 15 min. I'll install it in my truck and give it a run for it's money later today and report back.