Bob My manual shows 09-80103m05 is the part number for the female connector mounted on the interconnect board.
Ralph KA4DKJ ----- Original Message ----- From: Bob M.<mailto:[EMAIL PROTECTED]> To: [email protected]<mailto:[email protected]> Sent: Tuesday, February 05, 2008 5:04 PM Subject: Re: [Repeater-Builder] Re: Low-band MaraTrac Squelch Pots After soldering a wire from point-A to point-B, I thought I fixed the problem, but it persisted. I scoped all the signals on J21 and found that the one on pin 8 was going away. The connection from the audio board, at the back of the pin-side of the connector, to the logic board, and even the interconnect board, was going open when the squelch failed. No detected audio, no squelch operation. The socket at pin 8 of J21 seems to be defective. It's not gripping the pin coming in from the audio board. I can put a resistor lead into any of the other holes and feel the contact gripping the lead, but on pin 8 it just wobbles around. I could replace the connector IF I had a part number and IF Motorola still had one. It's an 18-pin female dual row, right-angle, 0.100 inch type. I didn't find one on Mouser, but did find a 2mm connector of the right style. The alternative is to solder a wire from the interconnect board directly to the pin 8 of J21 on the audio board. This would bypass the connector and insure it never fails again, but removing the board would require unsoldering the wire. I didn't expect this kind of failure. I have a feeling it was a defective part installed at the factory, and if the radio never had the need for carrier squelch, no one ever cared about it. Also, the connection would be good once in a while, so it might have worked when it left the factory and just decided to fail later in life. Bob M. ====== --- "Bob M." <[EMAIL PROTECTED]<mailto:msf5kguru%40yahoo.com>> wrote: > Problem temporarily solved. While tracing the > signals > around U1103, I found no Detected Audio coming into > pin 8 of J21, however when I pushed on the pin just > a > bit, the radio would then squelch up and the pot > worked like it should, along with the one on the > audio > board which was also dead. I pulled the audio board > but didn't find anything wrong. I resoldered pin 8 > and > put it back and it worked fine, until I started > bending the interconnect board near J21 in the front > of the radio. Now it's intermittent, so it looks > like > I'll have to pull that board and find the fractured > foil. Doesn't look like an easy board to pull > either, > since it's buried behind the front panel of the > chassis and has the big control connector on it. > > Bob M. > ======= > --- Milt <[EMAIL PROTECTED]<mailto:mengle%40pa.net>> wrote: > > > Bob, > > > > The info you need is contained in FMR-1735A-1 > dated > > June 1996 > > > > The Audio squelch board in the radio is replaced > > with HLN5342ESP01 > > > > From Pin 9 on the front connector (the former busy > > light line) on the > > interconnect board, the signal feeds through > JU1510 > > to pin 12 of J21 the > > audio board connector. JU1509 and 1511 are open, > > JU1512 is in. > > > > J21 pin 12 is the pin 2 input of U1103. JU1202 is > > out. > > > > IIRC busy light is not used on A7 heads with the > > remote squelch control > > option. > > > > It's possible that you have a missmatch between > the > > head and audio squelch > > board. > > > > Milt > > N3LTQ > > > > ----- Original Message ----- > > From: "Bob M." <[EMAIL PROTECTED]<mailto:msf5kguru%40yahoo.com>> > > To: <[email protected]<mailto:Repeater-Builder%40yahoogroups.com>> > > Sent: Monday, February 04, 2008 6:26 AM > > Subject: Re: [Repeater-Builder] Re: Low-band > > MaraTrac Squelch Pots > > > > > > > Thanks to the people who posted the link. I had > > seen > > > that page earlier but didn't follow the signal > off > > the > > > board. > > > > > > The pot in the control head seems to have its > arm > > and > > > one end connected to ground. The other end goes > > > through some resistors before leaving the > control > > > head. I can see the effect of turning the pot > down > > at > > > pin 9 of the control cable; it varies from about > > 3-5 > > > kOhms. I thought it was just a DC signal or just > a > > > varying resistance to ground. > > > > > > The schematic posted doesn't show the wiring > from > > the > > > audio board out to the pot on the control head. > > I'm > > > guessing that the signal coming into the squelch > > pot > > > on the audio board is detected audio, since it > > then > > > feeds the internal squelch pot which sets the > gain > > and > > > threshold of the squelch circuit. > > > > > > I'll have to rethink and evaluate this new > > > information. > > > > > > Bob M. > > > ====== > > > --- sgreact47 <[EMAIL PROTECTED]<mailto:echocomms%40hotmail.com>> wrote: > > > > > >> Bob, > > >> > > >> Look here for the modified audio board. > > >> > > >> http://www.batlabs.com/images/marsqsch.jpg<http://www.batlabs.com/images/marsqsch.jpg> > > >> > > >> The squelch control circuit is there, uses the > > >> Micor, MSF, high > > >> speed squelch. > > >> > > >> "Bob M." <[EMAIL PROTECTED]> wrote: > > >> > > > >> > I'm working on a 42-50 MHz MaraTrac with the > A7 > > >> > advanced head that has a squelch pot on it. > The > > >> > squelch is open all the time, and neither the > > >> control > > >> > head pot or the pot inside the radio will > close > > >> the > > >> > squelch. __________________________________________________________ Looking for last minute shopping deals? 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