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Author Topic: Trouble w/ Heathkit HD-1410  (Read 720 times)
NJ3U
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Posts: 125




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« on: March 04, 2009, 07:30:24 PM »

Recently licensed Technician would like troubleshooting insight on my used keyer. I bought it second hand to learn morse before going onto General and now I'm stuck!

I'm going to start from a point of assumption, it proably worked at one point !

When I power up the HD-1410 I hear the sidetone continiously, if I hit the paddles in either direction it responds with the proper dit or dah's.

Things I've checked already

No obvisous shorting from debris
External Key Jack is not shorted
Combination Speed and Pull to Hold works fine

Since the keyer functions "normally" except for the constant sidetone, it seems to me that it's a short that may be isolated to the circuitry driving that feature ?

Before I start lifting solder joints to check diodes, any pointers ?

Thanks in Advance,

73
KC2UML
Rory
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KA5N
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Posts: 4380




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« Reply #1 on: March 05, 2009, 03:07:13 AM »

One section of IC5 gates the sidetone.  I would try a new IC first.  Since all I have to refer to is a schematic I don't know whether the IC's are socketed.  If not and apparently you don't have much experience with troubleshooting, it is a bit difficult to remove multipin IC's without wrecking the PCB.  Probably a good idea to consult a local with more experience.
Allen
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NJ3U
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Posts: 125




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« Reply #2 on: March 05, 2009, 04:47:54 AM »

Thanks for the hint.  Yes the ic's are socketed so I'll just dig out my trusty / rusty socket jack and lift and reland him first.  Failing that I'll order up one and plug it in and hopefully that will clear this up!



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NJ3U
Member

Posts: 125




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« Reply #3 on: March 05, 2009, 07:51:25 AM »

OK, lifted and relanded the IC5 chip, no change to the situation.

So I'll start looking for replacement parts...

Other thoughts out there for troubleshooting or parts suppliers ?

73
KC2UML
RORY
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KQ6Q
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Posts: 995




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« Reply #4 on: March 06, 2009, 11:43:25 PM »

I've had a 1410 for years. Are you using with the AC supply, or external 12V ?
If you're going to key a solid state rig with it, you may have to short out a diode - it has diodes in the keying circuit so it could work with tube rigs that had positive and negative keying line voltages.
I remember causing the problem you're having when I substituted CMOS chips for the original TTL chips. I worked around the problem by changing the way the "pull to hold" switch on the speed control is wired. You don't need to hold key down on a solid state rig to work the tuner, so I wired the switch in series with the keying line. So before I turn on the keyer, I push the switch in, which disconnects it from the keying line. Once it's on, and through it's initial 'Dit' I pull the switch out and it's connected to the rig, and it's good to go. That was how I used it with a TenTec Argosy for 25 years.
I've had an Icom 746Pro for a few years now - it has a built-in keyer. I still use my 1410 for the paddles - removed the original headphone jack, put in a stereo phone jack with switching - so if nothing's plugged in, the paddles go to the circuit board as always - but if you plug in a three conductor 1/4 in plug, you now have the paddles to use with an external source. So I use a cable with 3-conductor 1/4" plugs on both ends, one for the keyer, one for the Icom. Cable plugged in, keyer is just paddles. Remove the cable, keyer is standalone unit. When I take the unit to field day, I have to explain that the active keyer speed control is the one on the rig, not on the keyer!
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NJ3U
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Posts: 125




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« Reply #5 on: March 07, 2009, 07:54:08 PM »

Thanks for the insight into various keyer scenarios.  At this point, I'm using the AC power cord.  

Having recently licensed technican, I'm studying morse so no transmissions for a while.  Couple of reasons for that position, no rig and no skill !

Taking a hint from KA5N, on the IC5 as a proable, I contacted KC8RP for original chip set and they should arrive next week.  

I'll start with the IC5 and go from there, hoping for a positive report next week.

Great Support from the ham elmer community !

73
Rory
KC2UML
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K2QPN
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Posts: 70




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« Reply #6 on: March 08, 2009, 02:53:13 PM »

Rory, I live nearby and have a scope and other test equipment. Be glad to give you a hand.

73,

Bob K2QPN
K2QPN@ARRL.NET
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NJ3U
Member

Posts: 125




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« Reply #7 on: March 09, 2009, 06:28:36 AM »

Bob,

Thanks for the offer, I'll keep that in mind.  I've ordered a chip set replacement and will try that first.

I'm active on 146.925 WARG machine, give me a call sometime.

73

Rory

KC2UML
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NJ3U
Member

Posts: 125




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« Reply #8 on: March 10, 2009, 08:15:28 PM »

Next Step or Suggestions Please...

I recieved and replaced all ic's today, no change.  Still have a solid side tone and the paddle works for both dits and dahs.

I took some voltage readings with ref on the chassis ground, several are suspect.  All other stated values are acceptable.

Suspect Values

Q4 collector 1  vdc should be 5 vdc
Q4 base      .7 vdc should be Logic low at ~ .09 vdc
Q5 emit      .8 vdc should be 5  vdc

ic5 pt4      1.2 vdc
ic5 pt5      1.5 vdc
ic5 pt6      .1  vdc

I'm thinking replacement of Q4(MPSA20) and / or Q5 (MS-D51)?

Thoughts / Suggestions ?

73
Rory
KC2UML



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K2QPN
Member

Posts: 70




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« Reply #9 on: March 14, 2009, 02:15:13 PM »

The offer is open to check out the keyer with my scope. Just drop me a note.

73, Bob k2qpn@arrl.net
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KA5N
Member

Posts: 4380




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« Reply #10 on: March 14, 2009, 04:04:28 PM »

Check value of R24, R25, and R16.  Check Q4 and Q5 for shorts.
Allen
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