Shakespeare Fortress dropout

[BBB]

Brought home a clean Shakespeare Fortress 40 Channel AM PLL transistor CB radio form the local auction. Another cool looking rig that reminds me of high end stereo equipment. I believe this radio is like the TRC455 or Fanon Fanfare 880DF in the fact that it has removable circuit cards and modules for the various stages.

Well it ran for about half an hour and then the receive started dropping out with just sounds of "arcing" heard thru the internal or external speaker. Sounds just like lightning strikes. Internal or external power supply doesn't matter. The transmit audio is fine. Mic connections are good (electronic keying) Tone control alters the sound normally. When the receive audio lowers and the arcing noises happen, I can drop it all out by turning down the volume control or operating the squelch. Rf gain doesn't do much to lower the arcing sound. PLL stays locked on displayed channel (There is a LED for PLL Unlock in case the PLL would become unlocked)

Clue maybe: arcing noise can be "seen" bumping the S meter even with the volume down, antenna connected or not, so obviously an internal issue. I usually attribute "arcing" sounds in playback audio with a capacitor that is failing or loose connection. I see a couple of 10 Volt electrolytic caps, bad JUJU.

Went back in this morning and cleaned up the pins on the mother board with deoxit and it worked again for about half an hour. Figured the issue is in the AF, RX or the PLL boards that occurs after a bit of warm up. I'm leaning more towards the RX board...Just asking if anyone else had this similar receive arcing noise problem with a Shakespeare Fortress, Realistic TRC455 or Fanon Fanfare 880DF?

Need to also find the right adjustment in the PLL module to bring it back on frequency; currently standing at 27.1138 for Ch 13. Adjustment may prove to be a bit tricky without board extenders so I'll probably have to make a 90 degree tool Anyone know how to adjust the frequency on the Shakespeare Fortress, TRC455 or Fanon Fanfare 880DF?

[Sandbagger]

Aug 5, 2014 11:41:26 GMT -5 BBB said:

Brought home a clean Shakespeare Fortress 40 Channel AM PLL transistor CB radio form the local auction. Another cool looking rig that reminds me of high end stereo equipment. I believe this radio is like the TRC455 or Fanon Fanfare 880DF in the fact that it has removable circuit cards and modules for the various stages.

Well it ran for about half an hour and then the receive started dropping out with just sounds of "arcing" heard thru the internal or external speaker. Sounds just like lightning strikes. Internal or external power supply doesn't matter. The transmit audio is fine. Mic connections are good (electronic keying) Tone control alters the sound normally. When the receive audio lowers and the arcing noises happen, I can drop it all out by turning down the volume control or operating the squelch. Rf gain doesn't do much to lower the arcing sound. PLL stays locked on displayed channel (There is a LED for PLL Unlock in case the PLL would become unlocked)

Clue maybe: arcing noise can be "seen" bumping the S meter even with the volume down, antenna connected or not, so obviously an internal issue. I usually attribute "arcing" sounds in playback audio with a capacitor that is failing or loose connection. I see a couple of 10 Volt electrolytic caps, bad JUJU.

Went back in this morning and cleaned up the pins on the mother board with deoxit and it worked again for about half an hour. Figured the issue is in the AF, RX or the PLL boards that occurs after a bit of warm up. I'm leaning more towards the RX board...Just asking if anyone else had this similar receive arcing noise problem with a Shakespeare Fortress, Realistic TRC455 or Fanon Fanfare 880DF?

Need to also find the right adjustment in the PLL module to bring it back on frequency; currently standing at 27.1138 for Ch 13. Adjustment may prove to be a bit tricky without board extenders so I'll probably have to make a 90 degree tool Anyone know how to adjust the frequency on the Shakespeare Fortress, TRC455 or Fanon Fanfare 880DF?

I'd put my money on bad caps. Get some freeze spray and when it starts going bad, hit a bunch of parts with the freeze and see if/when it clears up. That'll tell you where the bad part is.

[BBB]

Cool, literally.

I went in a checked a bunch of electrolytic caps. Only found one bad cap so far, but replacement didn't fix'er yet. Receive gets knocked way down after a while, then no more arc sounds are heard. Kind of like the failing cap finally stays shorted out. I can still barely hear 44 or my HT.

Hey on the bright side, the modules can be easily swapped so maybe a donor rig is the way to go. The TRC455 seams pretty common... if the boards are the same. Hard to say without schematics yet.

[Sandbagger]

Aug 5, 2014 16:31:04 GMT -5 BBB said:

Cool, literally.

I went in a checked a bunch of electrolytic caps. Only found one bad cap so far, but replacement didn't fix'er yet. Receive gets knocked way down after a while, then no more arc sounds are heard. Kind of like the failing cap finally stays shorted out. I can still barely hear 44 or my HT.

Hey on the bright side, the modules can be easily swapped so maybe a donor rig is the way to go. The TRC455 seams pretty common... if the boards are the same. Hard to say without schematics yet.

The other thing that I've seen on a couple of rigs (Most notably NDI chassis rigs like SBE's), is they use a PNP Germanium type transistor in one of the later stages, and it has a tendency to get "noisy".