Date   

Re: TM 504 Power Module Questions

sweetbeats
 

EJP thanks for that important information…to others as well.

So I’m realizing maybe some of my error in communication…I was assuming the reference “rear interface” was specific to the motherboard in the main frame. Does that terminology in this context actually refer to the backplane of the main frame? Like where the multi-pin connectors would be located on a main frame fitted with Option 2? If that’s the case I may have been confusing folks. None of my main frames have Option 2, and I don’t plan on implementing a home-grown retrofit. What I *am* interested in is a few specific interconnections mentioned earlier between main frame slots but just motherboard to motherboard using header pins and wire.

Cory Oace


Re: Tektronix RAMS (Surplus) Store - Odd hours?

Daniel Koller
 

To bring this back to topic, what are the sorts of things one finds at the store?  Still very curious even if I won't be able to shop there soon.Are the deals good?
  Dan

On Friday, July 16, 2021, 09:04:52 AM EDT, Daniel Koller <kaboomdk@...> wrote:

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-19
Please check back September 1, 2021

Very exciting! I'm really looking forward to this bit of normalcy returning.


Re: 7904A compress sweep

Harvey White
 

Good thought, could be that, but if the gain setting pot was intermittent, then I would expect it not to clip, since the amplifiers are designed to enable off screen deflection.

Perhaps another one?

Harvey

On 7/17/2021 8:14 AM, Precaud wrote:
Sounds like it could be as simple as an intermittent pot in the horizontal section.





Re: DM502 with problems

 

On Sat, Jun 6, 2020 at 09:40 AM, Dennis Tillman W7pF wrote:


Only one company is associates with bad IC sockets - that is Texas Instruments
Not all TI sockets were bad even if of course some could fail just like any other brands.
The one that stands out of the crowd is called C-95. In my opinion there is not a question
if it would fail but when. They were not only in TM500's but all over the place at that time.
Typically faults are intermittent and cleaning and reseating may help for some time but it
will eventually come back. If you see those in your instrument count on problems.
They are easily identified by the very unique profile on the short end.

Check on TekWiki here: https://w140.com/tekwiki/wiki/Bad_TI_IC_sockets

My three pictures at the bottom show it while the larger picture shows what I would not generally consider bad.

/Håkan


Re: DM502 with problems

Richard Peterson
 

Great feedback Harvey. I should have thought to inject the timer signal . . . I'll give that a try.

Jared - i found your video a few days ago. Thanks for taking the time to create/upload it.


Re: 7904A compress sweep

Precaud
 

Sounds like it could be as simple as an intermittent pot in the horizontal section.


Re: Fixing a 7603 Power Supply

 

On Sat, Jul 17, 2021 at 07:57 AM, Jeff Dutky wrote:


To my mind this emphasizes the importance of close visual inspection for
diagnosis and repair. Sure, lots of things are not visible to the eye, but
some are, and you can save a lot of time and effort by doing the visual
inspection first.
That and your systematic approach, Jeff.

Congratulations!

Cherish that 7603. The big screen is soo nice. I hope you can get your Option 1 out.

Raymond


Re: [HP-Agilent-Keysight-equipment] OT: Looking for a Pentium M765 (or maybe M780 - not sure it that will work)

 

Oh yes and I forgot - it needs to run Windows XP Embedded as some of the driver software doesn't like W7 or later.

David

-----Original Message-----
From: TekScopes@groups.io <TekScopes@groups.io> On Behalf Of David C. Partridge
Sent: 17 July 2021 09:56
To: TekScopes@groups.io
Subject: Re: [TekScopes] [HP-Agilent-Keysight-equipment] OT: Looking for a Pentium M765 (or maybe M780 - not sure it that will work)

Yes, I got that thanks, problem is there's no room inside the case to add a card like that.

David
-----Original Message-----
From: TekScopes@groups.io <TekScopes@groups.io> On Behalf Of cheater cheater
Sent: 16 July 2021 21:26
To: TekScopes <TekScopes@groups.io>
Subject: Re: [TekScopes] [HP-Agilent-Keysight-equipment] OT: Looking for a Pentium M765 (or maybe M780 - not sure it that will work)

That's why I linked you to a card that slots into a PCI slot and
provides you with a PC/104+ connector.

At which point the sky's the limit with inexpensive, powerful motherboards.


Re: [HP-Agilent-Keysight-equipment] OT: Looking for a Pentium M765 (or maybe M780 - not sure it that will work)

 

Yes, I got that thanks, problem is there's no room inside the case to add a card like that.

David

-----Original Message-----
From: TekScopes@groups.io <TekScopes@groups.io> On Behalf Of cheater cheater
Sent: 16 July 2021 21:26
To: TekScopes <TekScopes@groups.io>
Subject: Re: [TekScopes] [HP-Agilent-Keysight-equipment] OT: Looking for a Pentium M765 (or maybe M780 - not sure it that will work)

That's why I linked you to a card that slots into a PCI slot and
provides you with a PC/104+ connector.

At which point the sky's the limit with inexpensive, powerful motherboards.


Re: Members in Australia

Garth Daddy
 

Hi Allan, Sounds like a good idea, I just checked the site out it does not seem to have much going on? not many users?


Re: Members in Australia

momemeca
 

Thanks Allan :-)
It is so difficult to find vintage Tek stuff out here in Oz. We’re not as lucky as the folks in the U.S.A.
Cheers,
Rick
Melbourne - AUS

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!).





Re: Fixing a 7603 Power Supply

Tom Lee
 

Congratulations, Jeff! It's always nice to hear that perseverance pays off, and doubly nice that a couple jelly bean parts were all it took.

Cheers
Tom

Sent from an iThing; please forgive the terseness and typos

--
Prof. Thomas H. Lee
Allen Ctr., Rm. 205
350 Jane Stanford Way
Stanford University
Stanford, CA 94305-4070
http://www-smirc.stanford.edu

On Jul 16, 2021, at 22:24, "Jeff Dutky" <jeff.dutky@...> wrote:

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





Re: Fixing a 7603 Power Supply

 

Also, a comparatively minor success, but noteworthy: I also fixed a 7A18A that I was using to test the 7603, but which did not have any signal on Ch 2, nor any ability to adjust the vertical position. This fix is noteworthy because it is the third time I have found a malfunction in an instrument merely by visual examination (the other two times were the repair of my father's 475 which had a leaking wet tantalum cap on the sweep board, and the restoration of the vertical signal on both channels on the same scope that was the result of having unseated the channel switch IC while removing the case). In this instance it was a tiny resistor that joins the BNC connector to the position pot that was just dangling in the breeze. It took more time to warm up the soldering iron, and remove the metal covers on the front end than it did to reconnect the resistor. Now both channels on the 7A18A are working perfectly.

To my mind this emphasizes the importance of close visual inspection for diagnosis and repair. Sure, lots of things are not visible to the eye, but some are, and you can save a lot of time and effort by doing the visual inspection first.

-- Jeff Dutky


Re: Fixing a 7603 Power Supply

Dave Peterson
 

Nice job Jeff!

Great way to start the weekend. Save those dead transistors. Might make for interesting examples for the curve tracer when you get that up and running.

Dave

On Friday, July 16, 2021, 10:25:05 PM PDT, Jeff Dutky <jeff.dutky@...> wrote:

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


Re: Fixing a 7603 Power Supply

 

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


Re: Tektronix RAMS (Surplus) Store - Odd hours?

Jim Ford
 

Good deal!  I think we've taken this far enough off topic. ;)  To bring it back to Tek scopes, I am in the process of getting a hold of an 11800 series scope on the bay and selling my Atlas Sound 35RU rack.  The rack unfortunately was not beefy enough for my heavy HP microwave gear (nor for an 11800 series scope), but it might be useful for some of the smaller, lighter Tek gear like the TDS3000 series.  Or stuff it was designed for like audio equipment.        JimSent from my Verizon, Samsung Galaxy smartphone

-------- Original message --------From: Harvey White <madyn@...> Date: 7/16/21 8:33 PM (GMT-08:00) To: TekScopes@groups.io Subject: Re: [TekScopes] Tektronix RAMS (Surplus) Store - Odd hours? We were lucky enough to buy an empty lot, and have a house built on it.  The builder was just at the point where they would still consider custom modifications, so we put in a few, mostly having to do with insulation and support systems.However, I spent quite a few days putting in three runs of cat5e to every room, and two runs of RG6.That and video and 12 volts for surveillance cameras.HarveyOn 7/16/2021 10:03 PM, Jim Ford wrote:> 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: TekScopes@groups.io 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: TekScopes@groups.io 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: tekscopes@groups.io, TekScopes@groups.io 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.>> >>>> >>>> >>


Re: Members in Australia

Allan
 

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!).


Re: Tektronix RAMS (Surplus) Store - Odd hours?

Harvey White
 

We were lucky enough to buy an empty lot, and have a house built on it.  The builder was just at the point where they would still consider custom modifications, so we put in a few, mostly having to do with insulation and support systems.

However, I spent quite a few days putting in three runs of cat5e to every room, and two runs of RG6.

That and video and 12 volts for surveillance cameras.

Harvey

On 7/16/2021 10:03 PM, Jim Ford wrote:
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: TekScopes@groups.io 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: TekScopes@groups.io 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: tekscopes@groups.io, TekScopes@groups.io 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.>> >>>> >>



Re: DM502 with problems

Jared Cabot
 

I repaired one of these not too long ago, the video I made might help.

https://www.youtube.com/watch?v=Tx6DtLooCOs

My unit had drifting carbon composite resistors that were replaced, the usual sticky switches that were disassembled, cleaned, DeOxit-ised and relubricated (the gold wafer cam switches were only cleaned with alcohol and paper as mentioned earlier in this thread), and a faulty LD110 (faulty as it warmed up) that was successfully replaced with an eBay sourced part.


Re: DM502 with problems

Tom Lee
 

If the 555 is being fed with the right Vcc and the other components are ok (did you verify that the pot was working?), then you should see a clock output.

Finding a 555 is trivial, so you should have no problem finding a sub.

Good luck!

Cheers
Tom

Sent from my iThing, so please forgive brevity and typos

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







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