Xtant 1001 D

mike49504 · 2010-10-12 3:42 pm

I recieved this amp in for repair.

I believe the orginal power supply fets were the Z44's . The IRFZ48's are whats in it now. Will theese still work with the 10 ohm gate resistors?

Also Q3 thru Q10 and Q11 thru Q17 were also Z44's (orginals) and have been replaced with Z48's .

And last Q25 was IRL54 which now has a IRF540A in the amp.

Wondering if the Z48's will work in this amp since someone tryed repairing it before and within 15 mins in got stuck in protection mode and i have shorted transistors all thru the board now.

Perry Babin · 2010-10-12 4:33 pm

The IRL version of the IRF540 is a logic level FET. The standard IRF540 may not switch on/off efficiently and may run hot.

The Z48s will probably be OK.

Are the outputs shorted?

If so, what are they?

mike49504 · 2010-10-12 4:52 pm

2 of the outputs were shorted. The orginals were the Z44's atleast thats what MTX told me. The outputs that are in the amp now are the Z48's

Perry Babin · 2010-10-12 5:07 pm

I don't have any experience with this particular model. Similar amps are very sensitive to substitute outputs. I don't know if this one is. The Z48s should be OK in the supply.

mike49504 · 2010-10-26 2:22 am

Back to this amp ,

I replaced the 8 outputs back to irfz44's and the gate resistors are new.

I havent messed with the bias or dc offset pots.

Upon powering it up the blue light will come on for a few secs the shut off and amp will start drawing excessive current.

Any ideas on what to check?

Perry Babin · 2010-10-26 3:33 am

Have you tried removing the rectifiers to isolate the output from the power supply to see if the excessive current draw was eliminated?

mike49504 · 2010-10-26 4:52 am

Pulled all rectifiers from the amp. When i power up the amp the blue light will come on for a sec then the red light comes on and stays lit and amp idles perfectly

Perry Babin · 2010-10-26 4:59 am

Is this the amp you have:
Xtant 1001dx inside - Amp Guts

mike49504 · 2010-10-26 5:01 am

Perry Babin · 2010-10-26 5:15 am

I've never repaired one of these. What are the ICs on the riser board?

mike49504 · 2010-10-26 5:21 am

the long IC is

m74hc74b1
w991a9705

The 8 leg 1 is

TC4427cpa

Perry Babin · 2010-10-26 5:24 am

The 4427 is a driver IC and may have been damaged (assuming that the outputs failed originally and this IC drives the outputs).

mike49504 · 2010-10-26 5:26 am

Do you have the full part number so i can order a new IC ?

Perry Babin · 2010-10-26 5:27 am

TC4427cpa

mike49504 · 2010-10-28 2:19 am

ok i put the new driver ic in the amp and it idles to high still it idles around 5 to 6 amps of current.

Do i need to adjust the bias now? (the pot the says current adjust)

Perry Babin · 2010-10-28 2:56 am

The idle adjust is likely a deadtime adjustment. See if it lowers the idle current. If it does, set it like you would a normal bias adjustment and confirm that the output signal remains clean.

mike49504 · 2010-10-28 3:18 am

i adjusted it and amp idles fine now.

next problem is i have 25 volts of dc on the outputs

All outputs are new and gate resistors are new and the ic is new

Any ideas?

Perry Babin · 2010-10-28 3:20 am

What is the DC voltage measured directly across the positive and negative speaker terminals?

mike49504 · 2010-10-28 3:28 am

with the outputs in the amp 25.78 volts

With outputs out of the amp 6.95 volts

Perry Babin · 2010-10-28 3:33 am

I would need high quality photos of the board to help troubleshooting.

Did you have the both probes on the speaker terminals?

Xtant 1001 D

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