Jerrold Tekscan VSM-1

[on6iw]

hello , i am still looking for the schematics of the Jerrold Texscan VSM-1 or similar , you would make me very happy with that , my email [PRIVATE EMAIL ADDRESS REMOVED BY MODERATOR] thanks in advance , greetings from belgium , willy

[moderator: if anyone can help, please post the schematics or a link to them here.]

 

[Karl105]

hello , i am still looking for the schematics of the Jerrold Texscan VSM-1 or similar , you would make me very happy with that , my email [PRIVATE EMAIL ADDRESS REMOVED BY MODERATOR] thanks in advance , greetings from belgium , willy

[moderator: if anyone can help, please post the schematics or a link to them here.]

Hello,
I am looking for a VSM-1D also, someone applied 120Vac to the 12V dc input, I have most of it working except the IF input ckt? There are 4ea SK3242 Ic's which do not seem to be the same as the RCA replacements because of the pinout / DC voltages. This is somewhat difficult to work on and without schematic or what the IC's really are, it's trash. Any info would be helpful, especially on the IF, log amp, I know it has a 10Mhz input so that helps some. Almost all the IC's in this like new analyzer were blown. In the pic, there are 2ea 10 pin IC's under this mess, the board is now removed and I will try to verify the SK3242's are dead
This analyzer is very similar to the Texscan AL-50M

Thanks in advance
Karl

 

[on6iw]

Hello , Karl , yes it is very difficult to repair this without schematics , i will wait until i can find a manual somewhere , good luck with your repair
, i look for further information , 73 tu , Karl , all the best

 

[Karl105]

I did get it working however the signal level needs calibrating, After getting the pin 1 / Pin 10 straight on the IF amplifier, I was able to identify the IC, it is a MC1550G, my analyzer has SK3242's. It took over two hours to replace them but it is alive now. I have a AL-50M that works but looks rough so I will use that to compare. The ECG816 has pin 10 at the locater tab, the MC1550G has pin 1, I always had issues with this package. I had to remove board and lots of drawings before changing out the IC's, I did make sure they were dead before attempting anything.
I wonder why they used RCA SK series Ic's, How I identified is a long story.
I will install a internal 12 to 15 volt supply when finished
Thanks,
Karl

 

[on6iw]

Hi , Karl , congratulations on the repair , well done , i worked with this device in the 1970s , i worked for for a TV cable
compagny for 35 years , a revolutionary device at the time , but nouw it's now spring in Belgium and i have to do some work
in my garden and house , so i don't have much time , all the best , if you have once more information about this device , let me now , 73
tu and the very best for you and your family , sry for my poor englisch , gr willy

 

[Karl105]

As of now, the attenuator needs cleaning but my Boonton 102A, output died, dirty attenuator. The manual scan did not work , the section of the Manual / Auto switch open do I switched the failed connection to one not used.
The AL50M has a DBM scale (75ohm) and the VSM-1D has mv reference with neg db on the scale and the noise floor is -40db, the AL-50M has a -90dbm noise floor, confusing. I want to change the type F connector to a BNC, glad I have a good 75 to 50 ohm transformer.
As soon as I get the attn cleaned, I will start trying to figure the adjustment controls, this is where a manual would be very nice.
I was working on planting my garden seeds (indoor with artificial lights) and that took off already, they get planted outdoors in June
Karl

 

[Karl105]

Hello , Karl , yes it is very difficult to repair this without schematics , i will wait until i can find a manual somewhere , good luck with your repair
, i look for further information , 73 tu , Karl , all the best

As of now, the analyzer is working but the vertical output is low, good in center of screen, the MC1550G IC is a good replacement, confusion because of pin 1 and 10 being different, MC1550G is correct, ECG816 is not correct. good news is I had 3ea MC1550G's, 2.5 hours to replace
I need to attack the problem from a different direction, I believe I have the detected output identified, 20Db, 40DB and video output has additional unknown circuitry