Search found 83 matches

by mbrockm
Fri Sep 10, 2010 4:11 pm
Forum: AM Radio
Topic: SX5 digital pot AD7525
Replies: 44
Views: 5883

Re: SX5 digital pot AD7525

Got the retrofit kit from Harris. I have power control again. Yeah. Now I am finding an intermittent problem with the PA voltage pegging and Status 07 phase 1 voltage jumps to 260. Comes and goes. No surprise I can sometimes hear something arcing but can't locate the source, yet. But that comes and ...
by mbrockm
Tue Sep 07, 2010 12:49 pm
Forum: AM Radio
Topic: SX5 digital pot AD7525
Replies: 44
Views: 5883

Re: SX5 digital pot AD7525

yep. checked the pdm kill ckt and it is working correctly.
by mbrockm
Mon Sep 06, 2010 1:46 pm
Forum: AM Radio
Topic: SX5 digital pot AD7525
Replies: 44
Views: 5883

Re: SX5 digital pot AD7525

HarrisPDM.pdf Adjusting R28 does not do anything. Right now the power goes to full ,no matter what the power level ,even if its set to 00. The voltage on U2-14 charges up to about 13 volts or so. Once you turn on the power to the box U2-14 starts moving up even with out pressing low/med/high. So no...
by mbrockm
Fri Sep 03, 2010 3:55 pm
Forum: AM Radio
Topic: SX5 digital pot AD7525
Replies: 44
Views: 5883

Re: SX5 digital pot AD7525

I found 3 AD7525 ICs. Completely different control problem. Either full scale power out or no power out. Still no output from U3-1 no matter what I do. What is typical voltages for pin 1 out? Replaced CR5 and U2. No change. Voltage at U2-14 is erratic like a cap is charging. Tends to go negative vol...
by mbrockm
Tue Aug 31, 2010 3:14 pm
Forum: AM Radio
Topic: SX5 digital pot AD7525
Replies: 44
Views: 5883

Re: SX5 digital pot AD7525

Checked U2-13 is 0VDC no matter what the output power. R62,R63,R45, and R46 are about .5 volt with display 44 at .000
From what you said U3 is toast. U2-14 and U3-18 voltage changes from 0 - 10 volts with the S&M board.
by mbrockm
Mon Aug 30, 2010 10:44 am
Forum: AM Radio
Topic: SX5 digital pot AD7525
Replies: 44
Views: 5883

Re: SX5 digital pot AD7525

Sam, I can control power with U3 via the S&M board. Initially when it happened I found it took a very long time holding down the lower button before the power was back to a normal range and get output to 0 power out. Seems like some of the resistors in U3 either open or shorted out so the resistive ...
by mbrockm
Mon Aug 30, 2010 7:41 am
Forum: AM Radio
Topic: SX5 digital pot AD7525
Replies: 44
Views: 5883

Re: SX5 digital pot AD7525

I purchased the part on Ebay and hope this repairs the problem. The SX5 is our main and I am running on a Collins 820 for now. I am looking into a Nautel XR6 as a replacement for SX5. However money is tight so may not happen.
by mbrockm
Sun Aug 29, 2010 6:10 pm
Forum: AM Radio
Topic: SX5 digital pot AD7525
Replies: 44
Views: 5883

SX5 digital pot AD7525

Looking for someone with expertise on the SX5A. I trying to get a Harris SX5 back on air. Transmitter power output went into hyperdrive and pegged most of the front meters. Strangely did not trip out. It kept running and started blowing fuses and FETs. Tracked it down to U2 and U3 on the PDM generat...