开云体育

On 17 Jul 2021, at 14:25, Allan <saj507@...> wrote:

?HI Guys

Just thought I would mention an option for selling/buying gear in Australia/New Zealand (only) that does not have any fees at all! VK Classifieds (vkclassifieds.net.au) has been around for over 20 years and requires proof of ID to join and is mainly ham radio and electronics related. Free to join and Classifieds and Auctions are both available on the one site. Just an option as some sites are getting crazy with fees (and trolls!).

ACTUAL SUCCESS!

First I traced the INTENSITY control signal through the logic board, and checked Q90, Q108, and U99 (a C3046 transistor array). All of those checked out fine. Then I traced the gate signal from the logic board, through the main interface board, and to the Z-axis amp (it seems that I am fated to fix Z-axis amps). Once at the Z-axis amp I verified that the gate signal coincided with the signal I was triggering against (the front panel probe calibration signal) and then simply checked every transistor on the Z-axis board using my trusty component tester.

I found that Q1148 was bad. That's just a 2N3906, which I have plenty of, and replacing that brought traces to the CRT! Easy as pie.

I was also able to fully rejuvenate the INTENSITY pot by dripping Faderlube down the internal shafts of each pot section. I was never able to figure out how to get the pot sections open to clean the wiper and track, but that doesn't not seem to matter, as the Faderlube seems to have done the trick: the intensity pots are much smoother, and there's not more scratchiness or dead spots. I also applied DeoxIT to the switch at the end of the mod pot, which also helped make the switch action smoother and crisper.

Now it's on to "removing" Option 1 (aka installing a readout board). I have readout board, and the necessary Peltola cables, I just need to make the ribbon cables. I am studying the schematics so that I'm sure I understand all the connections that are needed.

It's a pretty good deal, getting a working 7603 for the price of two transistors (the PN2907A and the 2N3906).

-- Jeff Dutky

Funny you mention wired Ethernet, because I have my 3 computers, my work laptop, my home laptop, and lab tower, on a wired router.? All other computers in the house are on wireless, but my 3 are stationary and within a few tens of feet of each other.? That, and I wanted the speed, security, and reliability of wired.? The laptops could go wireless if I so chose; no need so far.? ? ? Jim?Sent from my Verizon, Samsung Galaxy smartphone
-------- Original message --------From: Harvey White <madyn@...> Date: 7/16/21 6:52 PM (GMT-08:00) To: [email protected] Subject: Re: [TekScopes] Tektronix RAMS (Surplus) Store - Odd hours? We've been working a long while to get a house that's even halfway setup for hobbies, and this is.? Wired ethernet in every room, RG6 for cable, etc....Naturally, of course, it's not big enough....or we have too much <- XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXNo idea what we do next, but I think it's time to figure out who in central florida would like some things, nothing wonderful, but possibly a makerspace or someone might like some old parts..... and a 30 inch direct view CRT tv... yeah, one of them, too....HarveyOn 7/16/2021 8:58 PM, Jim Ford wrote:> Nice setup, Harvey!? Well, we have 2 teens in the house. So they each have their own rooms.? Then there's the master bedroom and a 10 by 10 foot room for computers, scrapbooking, musical instruments, and as of last year, my home office.? ?One 2 by 5 foot bench and a 19-inch rack in the garage for my lab.? No room for visitors, and we make them go to a hotel.? Seems to work! ;)? ? ? ? ? JimSent from my Verizon, Samsung Galaxy smartphone> -------- Original message --------From: Harvey White <madyn@...> Date: 7/16/21? 2:50 PM? (GMT-08:00) To: [email protected] Subject: Re: [TekScopes] Tektronix RAMS (Surplus) Store - Odd hours? My wife has two bedrooms her own, for knitting, gourds, and whatever she wants.? I have one for a lab.? I also have the (shared) library for my books, TV, and recliner.? She has the family room for her TV and recliner.? The garage is full of combined stuff, the shop has an area for her, we're sharing what's left (although the kitchen is mostly mine) and we have ABSOLUTELY NO ROOM for guests.....unless they want to sleep in a recliner.Works for us..... <grin>HarveyOn 7/16/2021 5:27 PM, Jim Ford wrote:> I feel your pain, Dan!? If it weren't for my wife, my house would be full floor to ceiling with test equipment and musical gear!? OTOH, if it weren't for me, the wife would have it full of scrapbooking supplies and holiday decorations!? Either way it would be a no-brakes situation.? Good luck!? ? ? ? ? ?Jim FordSent from my Verizon, Samsung Galaxy smartphone> -------- Original message --------From: "Daniel Koller via groups.io" <kaboomdk@...> Date: 7/16/21? 6:04 AM? (GMT-08:00) To: [email protected], [email protected] Subject: Re: [TekScopes] Tektronix RAMS (Surplus) Store - Odd hours?? Hey, just out of curiosity, what sorts of things does one find these days at the RAMS store???Any vacuum tube stuff that someone dug up from storage, or retirees offices??What are the prices like?Is there a web page so one can see what it looks like in there?? These are not just idle questions.? My wife and I are seriously considering visiting some family in the Portland area, but unfortunately, in August, not after Sept. 1.? On the other hand, that's a good thing.? I should not be allowed in surplus stores, flea markets, or junk yards. (The catch is they are my wife's relatives, so if I bring anything home, I will not be visiting Portland any more).? ?Dan??? On Friday, July 16, 2021, 12:53:15 AM EDT, Magic_Smoke <jsymonds@...> wrote:? I got to answer my own question today, it's the 3rd Thursday of the month and I had the day off so I swung by. I found a sign next to the door that reads: RAMS Country Store is currently closed due to COVID-19Please check back September 1, 2021Very exciting! I'm really looking forward to this bit of normalcy returning.>> >>>> >>

On Jul 16, 2021, at 17:52, Harvey White <madyn@...> wrote:

This is a multiplexed display. There's a switch/transistor applying power to each of the displays in turn. That same switch changes the input of a single decoder to the various counters, likely through a multiplexer.

There's a counter that selects a digit and the appropriate input. If that counter doesn't run, you get whatever input there is to the decoder and the single digit much brighter than normal. Scanning averages out the peak current (selected) to the average current desired, hence the digits would be dimmer.

FIrst there needs to be a scanning clock. Secondly, the counter and decoding circuit that selects the digits needs to work.

If it's a 555, they're easy to come by. RadioShack/Tandy sold them, as did/does Jameco, etc.

If you had a signal generator that put out TTL pulses, I'd suggest pulling the 555 and patching a 1 Khz (roughly) output into the former output of the 555 timer and see how it goes. What their exact frequency is will be in the manual.

Depending on what state the decoding circuitry comes up in, you could be looking at any one of the counter outputs.

Analyze the circuit starting at the oscillator and go from there.

Harvey

On 7/16/2021 7:36 PM, Richard Peterson wrote:
Sorry for hijacking this discussion, but i'm working on a DM502 as well and wonder if you all could help. The unit powers on and has +5V and +/- 12V (step 1 of the check/adjustment procedure) but I don't have a clock signal - step 2. I'm guessing the NE555 timer IC is fried, but before i start randomly replacing parts, I checked out as much as i could. Voltages at various other points i tested seem OK and the resistors, capacitors and transistors within the display drive circuit all test OK as well. When the unit is powered up, i get a '0' on the display no mater what setting the switch is on with the decimal point showing up on a couple of the switch settings. Sometimes the display will go dark after being on for a while but not always. The sn7447 and LD110 ICs both feel very warm but not too hot to touch - maybe OK?

I tried Roger's suggestion to pull, clean and reseat the ICs but that didn't change anything. So . . . should i try just changing the NE555 to see if it comes back on line. Replace all the ICs? Are there other tests I can try to isolate the root cause of the problem? possibly a dirty switch?

Mouser has the NE555, the SN7447 and the SN7416N but the LD110 and LD111 appear to be approaching extinction although there is one seller on the fleabag selling sets.

Thanks for your help.

Rich

Nice setup, Harvey!? Well, we have 2 teens in the house. So they each have their own rooms.? Then there's the master bedroom and a 10 by 10 foot room for computers, scrapbooking, musical instruments, and as of last year, my home office.? ?One 2 by 5 foot bench and a 19-inch rack in the garage for my lab.? No room for visitors, and we make them go to a hotel.? Seems to work! ;)? ? ? ? ? JimSent from my Verizon, Samsung Galaxy smartphone
-------- Original message --------From: Harvey White <madyn@...> Date: 7/16/21 2:50 PM (GMT-08:00) To: [email protected] Subject: Re: [TekScopes] Tektronix RAMS (Surplus) Store - Odd hours? My wife has two bedrooms her own, for knitting, gourds, and whatever she wants.? I have one for a lab.? I also have the (shared) library for my books, TV, and recliner.? She has the family room for her TV and recliner.? The garage is full of combined stuff, the shop has an area for her, we're sharing what's left (although the kitchen is mostly mine) and we have ABSOLUTELY NO ROOM for guests.....unless they want to sleep in a recliner.Works for us..... <grin>HarveyOn 7/16/2021 5:27 PM, Jim Ford wrote:> I feel your pain, Dan!? If it weren't for my wife, my house would be full floor to ceiling with test equipment and musical gear!? OTOH, if it weren't for me, the wife would have it full of scrapbooking supplies and holiday decorations!? Either way it would be a no-brakes situation.? Good luck!? ? ? ? ? ?Jim FordSent from my Verizon, Samsung Galaxy smartphone> -------- Original message --------From: "Daniel Koller via groups.io" <kaboomdk@...> Date: 7/16/21? 6:04 AM? (GMT-08:00) To: [email protected], [email protected] Subject: Re: [TekScopes] Tektronix RAMS (Surplus) Store - Odd hours?? Hey, just out of curiosity, what sorts of things does one find these days at the RAMS store???Any vacuum tube stuff that someone dug up from storage, or retirees offices??What are the prices like?Is there a web page so one can see what it looks like in there?? These are not just idle questions.? My wife and I are seriously considering visiting some family in the Portland area, but unfortunately, in August, not after Sept. 1.? On the other hand, that's a good thing.? I should not be allowed in surplus stores, flea markets, or junk yards. (The catch is they are my wife's relatives, so if I bring anything home, I will not be visiting Portland any more).? ?Dan??? On Friday, July 16, 2021, 12:53:15 AM EDT, Magic_Smoke <jsymonds@...> wrote:? I got to answer my own question today, it's the 3rd Thursday of the month and I had the day off so I swung by. I found a sign next to the door that reads: RAMS Country Store is currently closed due to COVID-19Please check back September 1, 2021Very exciting! I'm really looking forward to this bit of normalcy returning.>> >>

Sorry for hijacking this discussion, but i'm working on a DM502 as well and wonder if you all could help. The unit powers on and has +5V and +/- 12V (step 1 of the check/adjustment procedure) but I don't have a clock signal - step 2. I'm guessing the NE555 timer IC is fried, but before i start randomly replacing parts, I checked out as much as i could. Voltages at various other points i tested seem OK and the resistors, capacitors and transistors within the display drive circuit all test OK as well. When the unit is powered up, i get a '0' on the display no mater what setting the switch is on with the decimal point showing up on a couple of the switch settings. Sometimes the display will go dark after being on for a while but not always. The sn7447 and LD110 ICs both feel very warm but not too hot to touch - maybe OK?

I tried Roger's suggestion to pull, clean and reseat the ICs but that didn't change anything. So . . . should i try just changing the NE555 to see if it comes back on line. Replace all the ICs? Are there other tests I can try to isolate the root cause of the problem? possibly a dirty switch?

Mouser has the NE555, the SN7447 and the SN7416N but the LD110 and LD111 appear to be approaching extinction although there is one seller on the fleabag selling sets.

Thanks for your help.

Rich