MSF TX VCO issue

TGundo 2003 · 2021-02-22T02:05:59-08:00

Good evening all! I have an MFS5000 UHF Digital station I'm trying got get back on the air. I'm really close to being done but have a nagging issue that has come to a head. I've had issues with the TX

MSF TX VCO issue

TGundo 2003 All Messages By This Member #183821 Good evening all! I have an MFS5000 UHF Digital station I'm trying got get back on the air. I'm really close to being done but have a nagging issue that has come to a head. I've had issues with the TX VCO going out of lock intermittently. I've taken it apart and cleaned it, though there were no "whiskers" visible, it was really clean. When it comes alive it will tune right up with no issues, I can set it to 38 microamps with ease. It will just randomly drop to 10 microamps and fall out of lock, and just as randomly pop back up. I've cleaned and reseated all connectors and the mainboard and it has not helped. It's progressively gotten worse, and now to the point it hardly locks at all. This is my first MSF, wondering if anyone has some guidance on where to start looking. Thanks! Tom W9SRV?
Bryon Jeffers K0BSJ All Messages By This Member #183824 Tom, ? I have had similar issues and all the problems were resolved by replacing/recapping the MSF uniboard, injection filter, IPA and interconnect board. Here is a link to help with the uniboard and injection filter <http://www.repeater-builder.com/motorola/msf/msf-uniboard-caps.html> and here is a link for the IPA? <http://www.repeater-builder.com/motorola/msf/msf-ipa-caps.html>. Next is the interconnect board <http://www.repeater-builder.com/motorola/msf/msf-ic-board-cap.html> and this 150 uf 16V cap is usually the main issue with the VCO's going in and out of lock. ? Hope this helps! ? Bryon Jeffers K0BSJ
colemanp2 #183830 Would this article apply to a VHF station that the rx vco isn not going into lock. toggle quoted message Show quoted text On 01/24/2021 6:36 AM Bryon Jeffers K0BSJ <k0bsj@...> wrote: ? ? Tom, ? I have had similar issues and all the problems were resolved by replacing/recapping the MSF uniboard, injection filter, IPA and interconnect board. Here is a link to help with the uniboard and injection filter <http://www.repeater-builder.com/motorola/msf/msf-uniboard-caps.html> and here is a link for the IPA? <http://www.repeater-builder.com/motorola/msf/msf-ipa-caps.html>. Next is the interconnect board <http://www.repeater-builder.com/motorola/msf/msf-ic-board-cap.html> and this 150 uf 16V cap is usually the main issue with the VCO's going in and out of lock. ? Hope this helps! ? Bryon Jeffers K0BSJ
TGundo 2003 All Messages By This Member #183834 Thanks, Byron! I don't want to have to visit this beast often so I think a full recap is in order. Tom W9SRV On Sunday, January 24, 2021, 05:37:06 AM CST, Bryon Jeffers K0BSJ <k0bsj@...> wrote: Tom, ? I have had similar issues and all the problems were resolved by replacing/recapping the MSF uniboard, injection filter, IPA and interconnect board. Here is a link to help with the uniboard and injection filter <http://www.repeater-builder.com/motorola/msf/msf-uniboard-caps.html> and here is a link for the IPA? <http://www.repeater-builder.com/motorola/msf/msf-ipa-caps.html>. Next is the interconnect board <http://www.repeater-builder.com/motorola/msf/msf-ic-board-cap.html> and this 150 uf 16V cap is usually the main issue with the VCO's going in and out of lock. ? Hope this helps! ? Bryon Jeffers K0BSJ
Bryon Jeffers K0BSJ All Messages By This Member #183878 Yes... The VHF has a couple different values but all in all bad caps effect both UHF and VHF in a bad way. I have recapped 5 different stations 3 UHF and 2 VHF. I will say the VHF seem to smoke more of the tantalum surface mount caps on the IPA than the UHF. Loud bang and then wonderful blue flame... Bryon K0BSJ
TGundo 2003 All Messages By This Member #183880 Byron- I pulled the mainboard today and took a closer look, found at least 4 caps obviously leaked out. Good call! Caps are on order to do the whole station. Thanks again for the help! Tom W9SRV On Sunday, January 24, 2021, 07:59:33 PM CST, Bryon Jeffers K0BSJ <k0bsj@...> wrote: Yes... The VHF has a couple different values but all in all bad caps effect both UHF and VHF in a bad way. I have recapped 5 different stations 3 UHF and 2 VHF. I will say the VHF seem to smoke more of the tantalum surface mount caps on the IPA than the UHF. Loud bang and then wonderful blue flame... Bryon K0BSJ
Sam Skolfield All Messages By This Member #183882 I also humbly recommend throughly cleaning and applying deoxit to the pins and sockets between the interconnect board and the uniboard, then work the pins in and out of the sockets over and over to clear everything up. Then do the same to the 6 pin molex connectors between the amplifier(s) and the interconnect board.? After the station is recapped and above is done, perform the factory alignment procedures.? Cheers.? KJ6QFS? toggle quoted message Show quoted text On Sun, Jan 24, 2021 at 6:23 PM, TGundo 2003 via <tgundo2003@...> wrote: Byron- I pulled the mainboard today and took a closer look, found at least 4 caps obviously leaked out. Good call! Caps are on order to do the whole station. Thanks again for the help! Tom W9SRV On Sunday, January 24, 2021, 07:59:33 PM CST, Bryon Jeffers K0BSJ <k0bsj@...> wrote: Yes... The VHF has a couple different values but all in all bad caps effect both UHF and VHF in a bad way. I have recapped 5 different stations 3 UHF and 2 VHF. I will say the VHF seem to smoke more of the tantalum surface mount caps on the IPA than the UHF. Loud bang and then wonderful blue flame... Bryon K0BSJ
TGundo 2003 All Messages By This Member #184076 Good evening all- Thanks to the recommendations of the group and the great write-ups on RB I have completed the recap. One more question- I don't see any mention of replacing caps on the control boards in the top section of the station. I see a few on there, do those normally not go bad? Or should I replace them as well? No write-ups cover them. Thanks again! Tom W9SRV
Sam Skolfield All Messages By This Member #184077 Hi Tom, Most certainly, they should be replaced. Everything electrolytic in the station should be replaced, IMHO. SSCB/SCB, uniboard, injection amplifier, ICB, IPA/ regulator.? Cheers, Sam? KJ6QFS? toggle quoted message Show quoted text On Wed, Feb 3, 2021 at 7:46 PM, TGundo 2003 via <tgundo2003@...> wrote: Good evening all- Thanks to the recommendations of the group and the great write-ups on RB I have completed the recap. One more question- I don't see any mention of replacing caps on the control boards in the top section of the station. I see a few on there, do those normally not go bad? Or should I replace them as well? No write-ups cover them. Thanks again! Tom W9SRV
Bob M. All Messages By This Member #184079 There are a lot more variations of the boards in the control tray, and very few electrolytics in critical positions. Most deal with DC filtering and audio, although the majority of the audio path is DC-coupled. It's also a lot more difficult to successfully remove and replace the SSCB and TTRC boards in the control tray. The pcb traces are also smaller and multi-layer, with a lot of surface-mount components on the underside to worry about, so the risk of damage is much greater, not to mention static precautions should be observed. The large caps in the power supply section of the analog Station Control Module definitely should be replaced. If you're going to replace ALL the electrolytic caps in the station, don't forget the power supply. Screw terminal caps are getting hard to find and thus are much more expensive. It might be worth disconnecting and measuring the capacitance of those big caps rather than outright replacing them.
TGundo 2003 All Messages By This Member #184282 Good evening all- Just finished up the recap- I did the ones on the control boards as I did find one leaked out. Put it all back together and of course, it seems more broken now... I get E40 & E41, and the PA Key light is dimly lit. Those error codes indicate a synthesizer problem. Does anyone want to hazard a guess which caps I screwed up? I took it slow and did them one by one to make sure I didn't screw up a value. I did them all on the anti-static mat with the straps on. Guess I need to go check each one again... Tom W9SRV
Bob M. All Messages By This Member #184287 Go (and this is the hard part) READ this article: About half way down there's a section called "Resolutions:" where it mentions some LEDs are lit dimly. Note the item dated 20-Jun-08 and the photo. Remove each of the filter/pin assemblies (two Torx screws) and measure each pin to the connector ground. You should get over 20 megohms on every pin. Scrape the crud off the ones that don't until they do. Check and clean both sides. Do each filter/pin assembly separately and remember how they go back in as there is a top and bottom, left and right. Use a permanent marker to make a mark in one corner of both the filter/pin assembly and the chassis.
TGundo 2003 All Messages By This Member #184298 Thanks for the link Bob! Well- the pins were all very clean, nothing metered bad. I cleaned them anyway. Took a closer look at the uniboard, found I put C368 in backward. It's in a group of three, obviously fudged it up not paying close attention to the + marking on the board. I got that flipped back, now the unit boots right up. At first, it all came alive, both VCO's working wonderfully. 5 minutes later I lost the TX VCO again, which is where I was when this all started. Back to the drawing board, I guess, perhaps there really is a problem with that VCO after all. When it boots up if I am listening on another radio I get some screeches and beeps coming thru while it boots. The RX is working great.? Tom W9SRV On Monday, February 15, 2021, 10:50:49 AM CST, Bob M. <wa1mik@...> wrote: Go (and this is the hard part) READ this article: About half way down there's a section called "Resolutions:" where it mentions some LEDs are lit dimly. Note the item dated 20-Jun-08 and the photo. Remove each of the filter/pin assemblies (two Torx screws) and measure each pin to the connector ground. You should get over 20 megohms on every pin. Scrape the crud off the ones that don't until they do. Check and clean both sides. Do each filter/pin assembly separately and remember how they go back in as there is a top and bottom, left and right. Use a permanent marker to make a mark in one corner of both the filter/pin assembly and the chassis.
Sam Skolfield All Messages By This Member #184301 Try swapping the VCOs?? toggle quoted message Show quoted text On Mon, Feb 15, 2021 at 5:43 PM, TGundo 2003 via <tgundo2003@...> wrote: Thanks for the link Bob! Well- the pins were all very clean, nothing metered bad. I cleaned them anyway. Took a closer look at the uniboard, found I put C368 in backward. It's in a group of three, obviously fudged it up not paying close attention to the + marking on the board. I got that flipped back, now the unit boots right up. At first, it all came alive, both VCO's working wonderfully. 5 minutes later I lost the TX VCO again, which is where I was when this all started. Back to the drawing board, I guess, perhaps there really is a problem with that VCO after all. When it boots up if I am listening on another radio I get some screeches and beeps coming thru while it boots. The RX is working great.? Tom W9SRV On Monday, February 15, 2021, 10:50:49 AM CST, Bob M. <wa1mik@...> wrote: Go (and this is the hard part) READ this article: About half way down there's a section called "Resolutions:" where it mentions some LEDs are lit dimly. Note the item dated 20-Jun-08 and the photo. Remove each of the filter/pin assemblies (two Torx screws) and measure each pin to the connector ground. You should get over 20 megohms on every pin. Scrape the crud off the ones that don't until they do. Check and clean both sides. Do each filter/pin assembly separately and remember how they go back in as there is a top and bottom, left and right. Use a permanent marker to make a mark in one corner of both the filter/pin assembly and the chassis.
Sam Skolfield All Messages By This Member #184302 Whoops, hit send too soon. Try swapping the VCOs just to see if TX will stay locked. Obviously not a permanent solution, they are different parts. But if it remains locked when you swap, then we can turn our attention towards the TX VCO.? PS, I forgot. Did you clean the VCOs yet? Another common problem: they get dendrites and junk in there. ?Disassemble the cavity part (screws on the side) and clean, alcohol and a swab will get down there in that tube.? toggle quoted message Show quoted text On Mon, Feb 15, 2021 at 6:56 PM, kj6qfs@... <kj6qfs@...> wrote: Try swapping the VCOs?? On Mon, Feb 15, 2021 at 5:43 PM, TGundo 2003 via <tgundo2003@...> wrote: Thanks for the link Bob! Well- the pins were all very clean, nothing metered bad. I cleaned them anyway. Took a closer look at the uniboard, found I put C368 in backward. It's in a group of three, obviously fudged it up not paying close attention to the + marking on the board. I got that flipped back, now the unit boots right up. At first, it all came alive, both VCO's working wonderfully. 5 minutes later I lost the TX VCO again, which is where I was when this all started. Back to the drawing board, I guess, perhaps there really is a problem with that VCO after all. When it boots up if I am listening on another radio I get some screeches and beeps coming thru while it boots. The RX is working great.? Tom W9SRV On Monday, February 15, 2021, 10:50:49 AM CST, Bob M. <wa1mik@...> wrote: Go (and this is the hard part) READ this article: About half way down there's a section called "Resolutions:" where it mentions some LEDs are lit dimly. Note the item dated 20-Jun-08 and the photo. Remove each of the filter/pin assemblies (two Torx screws) and measure each pin to the connector ground. You should get over 20 megohms on every pin. Scrape the crud off the ones that don't until they do. Check and clean both sides. Do each filter/pin assembly separately and remember how they go back in as there is a top and bottom, left and right. Use a permanent marker to make a mark in one corner of both the filter/pin assembly and the chassis.
TGundo 2003 All Messages By This Member #184305 Hi Sam! When this trouble started the first thing I did was clean out the VCO's. I Just swapped the TX & RX VCO's. The RX locked immediatly with the TX VCO in it, just had to peak it a little to get it to 38uA. The TX locked after a slight adjustment of the RX VCO in its chain, the Meter was pinned max in position 5, backed it down and it locked right in. So far so good... So I swapped them back, and again the RX locked immediatly with the RX VCO back in the correct position, just had to peak it up since I had adjusted it when it was on the TX side. The TX locked when I adjusted the TX VCO back in its place, again meter 5 was pinned so backed it down to 38uA and all seemed well. Keyed it up, made full power, sounded good. 5 Minutes later, the current on the TX VCO dropped to 10uA and it was unlocked again. This is what it seems to do, after a long preiod powered down it will come on and work for about 5 minutes before losing TX lock. I'm gong to assume the VCO is fine, but I didnt leave the VCO's swapped very long. Maybe I should do that next after it is powered down for a while, see if the TX VCO stays locked in the RX side. No harm in leaving that way a little while I assume? And I probably need to change that one cap on the 5V regulator on the interconenct board for good measure... Thanks! Tom W9SRV On Monday, February 15, 2021, 09:43:05 PM CST, Sam Skolfield <kj6qfs@...> wrote: Whoops, hit send too soon. Try swapping the VCOs just to see if TX will stay locked. Obviously not a permanent solution, they are different parts. But if it remains locked when you swap, then we can turn our attention towards the TX VCO.? PS, I forgot. Did you clean the VCOs yet? Another common problem: they get dendrites and junk in there. ?Disassemble the cavity part (screws on the side) and clean, alcohol and a swab will get down there in that tube.? toggle quoted message Show quoted text On Mon, Feb 15, 2021 at 6:56 PM, kj6qfs@... <kj6qfs@...> wrote: Try swapping the VCOs?? On Mon, Feb 15, 2021 at 5:43 PM, TGundo 2003 via <tgundo2003@...> wrote: Thanks for the link Bob! Well- the pins were all very clean, nothing metered bad. I cleaned them anyway. Took a closer look at the uniboard, found I put C368 in backward. It's in a group of three, obviously fudged it up not paying close attention to the + marking on the board. I got that flipped back, now the unit boots right up. At first, it all came alive, both VCO's working wonderfully. 5 minutes later I lost the TX VCO again, which is where I was when this all started. Back to the drawing board, I guess, perhaps there really is a problem with that VCO after all. When it boots up if I am listening on another radio I get some screeches and beeps coming thru while it boots. The RX is working great.? Tom W9SRV On Monday, February 15, 2021, 10:50:49 AM CST, Bob M. <wa1mik@...> wrote: Go (and this is the hard part) READ this article: About half way down there's a section called "Resolutions:" where it mentions some LEDs are lit dimly. Note the item dated 20-Jun-08 and the photo. Remove each of the filter/pin assemblies (two Torx screws) and measure each pin to the connector ground. You should get over 20 megohms on every pin. Scrape the crud off the ones that don't until they do. Check and clean both sides. Do each filter/pin assembly separately and remember how they go back in as there is a top and bottom, left and right. Use a permanent marker to make a mark in one corner of both the filter/pin assembly and the chassis.
n3ssl All Messages By This Member #184306 Hi, Take the VCO units apart they? like Ge Mastr Series develop whiskers.? I experienced this on a 900 station last year.? was doing all sorts of strange things.? ?I took detoxit spray and a compressed air and paper towels and cleaned. the VCO units up and working ever since.? n3ssl?
Sam Skolfield All Messages By This Member #184308 Yep, like I said. They both need precautionary cleaning. Will save you headache down the line trust me.? toggle quoted message Show quoted text On Tue, Feb 16, 2021 at 7:51 AM, n3ssl via <n3ssl@...> wrote: Hi, Take the VCO units apart they? like Ge Mastr Series develop whiskers.? I experienced this on a 900 station last year.? was doing all sorts of strange things.? ?I took detoxit spray and a compressed air and paper towels and cleaned. the VCO units up and working ever since.? n3ssl?
Sam Skolfield All Messages By This Member #184309 Hey Tom! Yep, sounds like the TX VCO needs a scrub. Definitely hit both while you’re at it. If the problem persists, then we can start attacking the actual circuitry of the TX VCO, or I can send you one.? toggle quoted message Show quoted text On Tue, Feb 16, 2021 at 9:21 AM, kj6qfs@... <kj6qfs@...> wrote: Yep, like I said. They both need precautionary cleaning. Will save you headache down the line trust me.? On Tue, Feb 16, 2021 at 7:51 AM, n3ssl via <n3ssl@...> wrote: Hi, Take the VCO units apart they? like Ge Mastr Series develop whiskers.? I experienced this on a 900 station last year.? was doing all sorts of strange things.? ?I took detoxit spray and a compressed air and paper towels and cleaned. the VCO units up and working ever since.? n3ssl?
Sam Skolfield All Messages By This Member #184310 I missed my coffee today sorry. I see now you cleaned them already!? toggle quoted message Show quoted text On Tue, Feb 16, 2021 at 9:24 AM, Sam Skolfield via <kj6qfs@...> wrote: Hey Tom! Yep, sounds like the TX VCO needs a scrub. Definitely hit both while you’re at it. If the problem persists, then we can start attacking the actual circuitry of the TX VCO, or I can send you one.? On Tue, Feb 16, 2021 at 9:21 AM, kj6qfs@... <kj6qfs@...> wrote: Yep, like I said. They both need precautionary cleaning. Will save you headache down the line trust me.? On Tue, Feb 16, 2021 at 7:51 AM, n3ssl via <n3ssl@...> wrote: Hi, Take the VCO units apart they? like Ge Mastr Series develop whiskers.? I experienced this on a 900 station last year.? was doing all sorts of strange things.? ?I took detoxit spray and a compressed air and paper towels and cleaned. the VCO units up and working ever since.? n3ssl?

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MSF TX VCO issue