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I began checking out a new-to-me RV75 this AM and am seeing some issues I dont yet understand. These are:

1. While the RV75 seems to be working in a basic fashion, the frequency displayed on the TR7 varies by as much a 2 KHz over time, even with an extneded warmup and without touching the tuning knob.
2. It is nearly impossible to set the frequenciny to the desired 100 Hz increment; very small movements of the tuning knob produce a few hundred Hz change in the displayed frequency.
3. The "Fixed Frequency" feature does not display the programmed frequency. Programming is a bit convoluted but I have verified several times that the switch settings are as described in the manual.

This is a a late serial number RV75 in very nice overall condition and was serviced by Ron Baker in 2015; his invoice shows only minimal work needed. My TR7 works as expected with an RV7 in place of the RV75.

So, wondering how best to proceed. Problems may be pilot error due to lack of familiarity, but if so, not clear what the pilot is doing wrong. I have a manual? but am reluctant to dive into troubleshooting without a better understanding as to what might cause these symptoms. Any guidance appreciated.

Rick
K8EZB?

On Mon, Mar 13, 2023 at 10:46 AM, John K5MO wrote:

Do you have the pushbutton in the TUNE position?

Yes, with both Fixed Feq buttopns out.

RB

I have experienced dirty pushbuttons and small electrolytics that failed miserably in my RV75. They were Capar branded. If you have those replace them.

73

-Jim
NU0C

On Mon, 13 Mar 2023 10:23:47 -0700
"Rick Boswell" <frboswell@...> wrote:

I began checking out a new-to-me RV75 this AM and am seeing some issues I dont yet understand. These are:

1. While the RV75 seems to be working in a basic fashion, the frequency displayed on the TR7 varies by as much a 2 KHz over time, even with an extneded warmup and without touching the tuning knob.
2. It is nearly impossible to set the frequenciny to the desired 100 Hz increment; very small movements of the tuning knob produce a few hundred Hz change in the displayed frequency.
3. The "Fixed Frequency" feature does not display the programmed frequency. Programming is a bit convoluted but I have verified several times that the switch settings are as described in the manual.

This is a a late serial number RV75 in very nice overall condition and was serviced by Ron Baker in 2015; his invoice shows only minimal work needed. My TR7 works as expected with an RV7 in place of the RV75.

So, wondering how best to proceed. Problems may be pilot error due to lack of familiarity, but if so, not clear what the pilot is doing wrong. I have a manual? but am reluctant to dive into troubleshooting without a better understanding as to what might cause these symptoms. Any guidance appreciated.

Rick
K8EZB

Following up on my OP on this topic from Mar, 2023. I have finally gotten around to some basic troubleshooting on this otherwise pristine RV75 and have discovered a damaged resistor as shown in the photo album “RV75 Failed Resistor.” The damage to this resistor makes reading the color code “iffy.” Can anyone identify the Rxxx designation (and value) for this resistor?

Thanks

Rick

K8EZB

Click on "Photos" at the upper lefthand side of the "Messages" page. My photo is currently the first on the list and is labeled "RV75 ...."

RB

Looks like maybe 10K. Same as the one next to it. It does not seem to be shown on the schematic I am looking at.

Side note: if you have any Capar brand electrolytics on the boards, REPLACE THEM. They misspelled the name, it should be "CRAPar".

73

-Jim
NU0C

On Thu, 25 Jan 2024 09:07:48 -0800
"Rick K8EZB" <frboswell@...> wrote:

Following up on my OP on this topic from Mar, 2023. I have finally gotten around to some basic troubleshooting on this otherwise pristine RV75 and have discovered a damaged resistor as shown in the photo album “RV75 Failed Resistor.” The damage to this resistor makes reading the color code “iffy.” Can anyone identify the Rxxx designation (and value) for this resistor?

Thanks

Rick

K8EZB

--

73

-Jim
NU0C

Jim,

Thanks for the quick reply and photo. Yes, based on your photo, it does look like 10K (keeping in mind that I am looking at the RV75 for the first time ever!).

I am inclined to tack in a new resistor to see if this restores proper operation. If not, I lack the skills, soldering tools and test equipment to go further. Also, this RV75 has plenty of?"CRAPar" capacitors. I am looking for someone who will take on the task of further troubleshooting, appropriate parts replacement and testing. Given the scarcity of the RV75, I am inclined to want to fix it rather than junk it. Any suggestions appreciated.

Best,

RB

Good catch. I missed that one. 150 Ohms in the pic I attached. Looks like it is the resistor in series with L205. Better check CR207 for damage too.

73

-Jim
NU0C

On Thu, 25 Jan 2024 09:48:49 -0800
"VE7PS" <ve7ps@...> wrote:

Rick:

You actually seem to have TWO failed resistors there. One is just above
P/J 206 in the pic - the one that's split in half...but if you look to the
right of that P/J, you'll see another burned resistor. I can open my RV-75
and take a look within the hour. Schematic isn't helping much and want to
be sure.

73
Peter
VE7PS

On Mon, Mar 13, 2023 at 10:23?AM Rick Boswell <frboswell@...> wrote:

I began checking out a new-to-me RV75 this AM and am seeing some issues I
dont yet understand. These are:

1. While the RV75 seems to be working in a basic fashion, the frequency
displayed on the TR7 varies by as much a 2 KHz over time, even with an
extneded warmup and without touching the tuning knob.
2. It is nearly impossible to set the frequenciny to the desired 100 Hz
increment; very small movements of the tuning knob produce a few hundred Hz
change in the displayed frequency.
3. The "Fixed Frequency" feature does not display the programmed
frequency. Programming is a bit convoluted but I have verified several
times that the switch settings are as described in the manual.

This is a a late serial number RV75 in very nice overall condition and was
serviced by Ron Baker in 2015; his invoice shows only minimal work needed.
My TR7 works as expected with an RV7 in place of the RV75.

So, wondering how best to proceed. Problems may be pilot error due to lack
of familiarity, but if so, not clear what the pilot is doing wrong. I have
a manual but am reluctant to dive into troubleshooting without a better
understanding as to what might cause these symptoms. Any guidance
appreciated.

Rick
K8EZB

--

73

-Jim
NU0C

Right off the top of my head is you may be seeing power source issues due to failed caps. The Capars are evil incarnate, but it would not be a bad idea to recap all of the electros.

I have too many project right now, so don't even ask. :) Two broken amps to fix, a third for another ham, two FM rigs for yet another fellow, two Alpha amps to clean up and put online, and the list goes on....

73

-Jim
NU0C

On Thu, 25 Jan 2024 09:57:21 -0800
"Rick K8EZB" <frboswell@...> wrote:

Jim,

Thanks for the quick reply and photo. Yes, based on your photo, it does look like 10K (keeping in mind that I am looking at the RV75 for the first time ever!).

I am inclined to tack in a new resistor to see if this restores proper operation. If not, I lack the skills, soldering tools and test equipment to go further. Also, this RV75 has plenty of "CRAPar" capacitors. I am looking for someone who will take on the task of further troubleshooting, appropriate parts replacement and testing. Given the scarcity of the RV75, I am inclined to want to fix it rather than junk it. Any suggestions appreciated.

Best,

RB

--

73

-Jim
NU0C

Steve,

Yes, good catch! I was so preoccupied with the obvious failed resistor that I overlooked the other failed resistor.

Jim,

you may be seeing power source issues due to failed caps.

My first thougfhts as well. With two failed resistors it makes no sense to simply replace the resistors. I need to find what is causing these to fail. The caps are a good place to start. Can you recommend suitable replacements, especially of appropriate physical size?

Looks like I am going to learn more about the RV75 than I ever wanted to know!

Best,

RB

?

Peter,

Thanks for the additional info.

I do have a list. I'll see if I can dig it up for you a bit later.



On Thu, 25 Jan 2024 10:59:33 -0800
"Rick K8EZB" <frboswell@...> wrote:

The caps are a good place to start. Can you recommend suitable replacements, especially of appropriate physical size?

--

73

-Jim
NU0C

Which Jim? :D

Well, if he would quit using the Steve font....

73

-James



On Thu, 25 Jan 2024 11:35:29 -0800
"Rick K8EZB" <frboswell@...> wrote:

Peter,

Thanks for the additional info.

On Thu, Jan 25, 2024 at 11:24 AM, VE7PS wrote:

Why do people keep calling me Steve?

Only because Jim did. That's mild compared to what some call me!? ;-)

RB

--

73

-Jim
NU0C

This is the list from my Mouser project file. Note: I usually order extras beyond what I need, especially if I am near a price break. I am also attaching my log of measured values of the old caps if you need any convincing on the Capars. Open Office spreadsheet.

Mouser # Mfr. # Manufacturer Customer # Description Order Qty.
594-2222-138-15102 MAL213815102E3 Vishay Aluminum Electrolytic Capacitors - Axial Leaded 1000uF 16V 20% Axial RoHS Compliant 3
594-2222-138-25101 MAL213825101E3 Vishay Aluminum Electrolytic Capacitors - Axial Leaded 100uF 16V 20% Axial RoHS Compliant 2
594-2222-138-35229 MAL213835229E3 Vishay Aluminum Electrolytic Capacitors - Axial Leaded 22uF 16V 20% Axial RoHS Compliant 10
75-TE1155-E3 TE1155-E3 Vishay Aluminum Electrolytic Capacitors - Axial Leaded 16V 10uF AXIAL RoHS Compliant 3



On Thu, 25 Jan 2024 10:59:33 -0800
"Rick K8EZB" <frboswell@...> wrote:

Can you recommend suitable replacements, especially of appropriate physical size?

--

73

-Jim
NU0C

Jim,

Thanks for the cap info. Will get an orrder in shortly. Want to do some in-circuit testing first. I am beginning to think I might actually be able to do this!??

Best,

RB