Heathkit Service Bulletins - HD-XX Series (Revised)
Joseph W Lutz
joelutz at JUNO.COM
Fri Dec 12 21:40:07 EST 1997
May 20, 1971
HD-10 Bulletin No:
Electronic Keyer HD-10-1F
A vender change on this four-pin socket make it unuable. All units in
stock are being corrected - - but a run of HD-10 units has been shipped
with this incorrect socket.
An insert is being prepared advising the customer to solder the
transistors directly to the circuit board---eliminating the need for this
part. Any future production will not use this part.
Please advise any customer purchasing an HD-10 to discard the sockets &
install transistors directly on the circuit board. Also, watch for this
problem when servicing the HD-10.
------------------------------------------------------------------------------------------------------------------
MAY 23, 1974
HD-10 Bulletin No:
Electronic Keyer HD-10-1
Service Guide HD-10 Keyer
The following steps are a troubleshooting sequence you can use to isolate
each stage of the keyer and check its operation. It is difficult to
check circuits when the keyer is in operation because voltages change
rapidly. With this troubleshooting sequence, you can stop the keyer
action in each state of operation to check voltages and other circuit
conditions. After you pinpoint the area of trouble, check all parts and
connections in the associated circuitry.
1. Measure voltages at the points shown in figure 9 on page 32 of the
manual. This checks the circuits for proper bias voltages while they are
at rest. In this condition, each multivibrator has one transistor cut
off and the other saturated, the clamp transistors are all saturated, and
the switch tansistor and its driver are both cut off. The following
transistors will be saturated while the circuits are at rest: Q1, Q3,
Q5, Q6, Q9 and Q11.
The following conditions exist when a transistor is cut off: No collector
current flows; the collector voltage will be nearly at the supply
voltage; and the base will be biased negatively with respect to the
emittor for NPN transistors [2N2712], or positively for PNP transistors
[2N407 and 2N398A].
The following conditions exist when a transistor is saturated: its
collector voltage will be nearly the same as its emitter voltage; if the
voltage between the emitter and base is measured, the base will be biased
toward the supply voltage, silightly positive for NPN transistors, and
slightly negative for PNP transistors.
2. Remove Q11. Now the audio tone whould be on, indicating that the
audio circuitry works. Replace Q11.
3. Ground the hand key terminal. A tone should be heard, showing that
Q1 is working, and the transmitter should key, indicating that Q8 is
working. Remove the ground.
4. Remove Q5. A tone indicates that Q7 is working.
5. Measure the emitter-to-base voltage of Q6. A base reading of about 2
volts negative to the emitter indicates that Q6 is receiving the
dash-completion voltage.
6. Ground the base of Q2. Measure the base-to-emitter voltage of Q3. A
reading that shows the base is about 1 volt negative with respect to the
emitter indicates proper dash-completion voltage from Q5 to Q3. Replace
Q5.
7. Ground the base of Q2. Momentarily ground the base of Q5: This
should cause the tone to go on and stay on until the base of Q4 is
momentarily grounded. This indicates that the flip-flop multivibrator is
working. Remove the ground from the base of Q2.
8. Momentarily ground the base of Q5. A short-duration tone signal
indicates that the completion circuitry is working.
9. Remove Q1. the tone should be heard, indicating that the dot signal
is reaching Q7.
10. Measure the base-to-emitter voltage of Q3. a reading that shows the
base is about 2 volts negative with respect to the emitter indicates that
proper dot-completion voltage is reaching Q3. Replae Q1.
11. Remove Q3. Dots should be heard, indicating that the dot generator
is working.
12. Remove Q6. Dashes should be heard, indicating that the
multivibrators are all working. Replace Q3 and Q6.
13. Measure the base-to-emitter voltge of Q3, with the paddle at the
dots position. This voltage should show that the base is about 4 volts
negative, indicating proper dot keying.
14. Measure the base-to-emitter voltage of Q6, with the paddle at dots.
the base voltage should remain positive with respect to the emitter.
15. Measure the base-to-emitter voltage of Q6, with the paddle at
dashes. The base voltages at both Q6 and Q3 should show that these bases
are about 5 volts negative with respect to their emitters,
16. Note: It may also be helpful to refer to the oscilloscope waveforms
in the circuit description, Similar waveforms would be obtained in your
keyer if an oscilloscope with good low-frequencey response is available.
The oscilloscope must be capable of fast rise-time to see the trigger
pulse shown in figure 14, since this pulse is extremely short. A 10:1
divider probe should be used with the oscilloscope to avoid loading the
trigger pulses with cable capacitance.
-----------------------------------------------------------------------------------------------------------------
January 24, 1975
HD-10 Bulletin No:
Keyer HD-10-2
Improper Grounding
When servicing a keyer that is inoperative, check for proper grounding
at:
1. The on-off switch.
2. The two ground lugs on the chassis rear panel.
3. The phone jack on chassis rear panel.
Be sure all hardware at these points is secure.
-------------------------------------------------------------------------------------------------------------------
Thats everything I hold up to 1985 that covers the HD-10 Keyer.
-------------------------------------------------------------------------------------------------------------------
January 31, 1975
HD-15 Bulletin No:
Phone Patch HD-15-1
Service Notes
The major complaint is not enough isolation between transmit and receive
circuits. This results in cycling between transmit and receive when
attempting VOX operation. Replacing the hybrid transformer could be
tried, but this usually does not cure the problem. Sometimes the VOX
gain in the transmitter is adjusted too high. When the unit is
determined to be operating satisfactorily, try to convince the customer
of the advantage of push-to-talk operation. "You have control over what
is being said, and you will also prevent both parties from doubling, or
talking at the same time."
The VU meter indicates only signal from the receiver into the patch.
Customers seem to think that the VU meter should indicte when a signal is
being fed from the phone line into the phone patch. This is not so. In
the case of the HM-15, a -10 VU level appeared to be giving satisfactory
operation.
--------------------------------------------------------------------------------------------------------------------
January 23, 1978
HD-15 Bulletin No:
Phone Patch HD-15-2
Phone Patch/Bell System Interface
The HD-15 Phone Patch is not registered with the FCC for use directly
with telephone lines. The Bell System will require a special line
couple, model QKT, for connection to their lines.
--------------------------------------------------------------------------------------------------------------------
Thats everything I hold up to 1985 that covers the HD-15 Phone Patch.
--------------------------------------------------------------------------------------------------------------------
August 10, 1973
HD-20 Bulletin No:
Crystal Calibrator HD-20-1
Battery Shorting To Case
In some of the older HD-20 calibrators, there is a possiblitity of the
battery sliding in its clamp, shorting to the case. This can be
eliminated by installing insulator paper [PN 75-93] on the inside of the
case, directly off each end of the battery. [2 required].
------------------------------------------------------------------------------------------------------------------
Thats everything I hold up to 1985 that covers the HD-20 Crystal
Calibrator.
------------------------------------------------------------------------------------------------------------------
October 10, 1977
HD-1250 Bulletin No:
Solid State Dip Meter HD-1250-1
Calibration of Oscillator Circuit & Check-Out of Detector
Circuit Operation
++++Information not yet available++++
------------------------------------------------------------------------------------------------------------------
February 27, 1981
HD-1250 Bulletin No:
Solid State Dip Meter HD-1250-2
Low or No Meter Indication With Brown Coil Installed
++++Information not yet available++++
------------------------------------------------------------------------------------------------------------------
July 30, 1982
HD-1250 Bulletin No:
Solid State Dip Meter HD-1250-3
Will Not Oscillate at High Frequency
++++Information not yet available++++
-----------------------------------------------------------------------------------------------------------------
January 18, 1985
HD-1250 Bulletin No:
Solid State Dip Meter HD-1250-4
Oscillator Dead
On the oscillator board, check Q11 [PN 417-290] for short between
collector and transistor case. The metal case on the #417-290
transistors should be isolated from the collector. Defective transistors
found in Parts Replacement stock and kits in finished goods had a date
code of 413. Heath Parts Replacement stock has been 100% checked.
Finished goods will be inserted with good #417-290 transistors.
--------------------------------------------------------------------------------------------------------------------
February 8, 1985
HD-1250 Bulletin No:
Solid State Dip Meter HD-1250-5
Unit Oscillates Without Coil Installed
The circuitry of Q21 self-oscillates when no coil is installed, causing a
full-scale deflection of the meter. To correct this problem, install a
ferrite bead [PN 475-15] on the G1 lead of Q21.
The next production of kits will have the ferrite bead and insert [PN
591-4661]. Present stock of kits will not be inserted.
--------------------------------------------------------------------------------------------------------------------
Thats everything I hold up to 1985 that covers the HD-1250 Solid State
Dip Meter.
--------------------------------------------------------------------------------------------------------------------
April 17, 1975
HD-1410 Bulletin No:
Electronic Keyer HD-1410-1
Modifications For Use With Ten-Tec, Triton And
Rigs With Similar Keying Requirements
It has been found that the Ten-Tec Argonaut and Triton keyin circuits
require that the key-line be brought to within a few tenths of a volt of
ground to operate properly, Either of the following modifications to the
HD-1410 will allow it to be used with the above units:
A. If the Hd-1410 is to be used exclusively with the Ten-Tec or rigs
with similar requirements, R27 and D5 can be replaced with jumper wires.
This disables Q7 and eliminates the .7 volt drop due to D5.
B. If the HD-1410 is to be used both with such rigs and cathode or grid
block keyed rigs, the modification shown on the attached schematic may be
made. The jack labelled " Ext. Key" becomes a secondary "keyer-out" jack
for use only with rigs employing a positive key line, and solid state
keying circuit.
1. Refer to page 40 of assembly manual and remove the wire between jack
L, lug 1 [Keyout Jack] and circuit board hole F.
2. Disconnect the remaining wire from jack L, lug 1 and connect to
circuit board hole F.
3. Mount terminal strip and components as shown:
[[Shows TS 431-62 To be mounted under top screw of Jack L and bent
down slightly. Connect a 4700 Ohm resistor between lugs 1 and 3 of TS
431-62. Connect base of [PN 417-801] to lug1 of TS 431-62; emitter to
one lug of Jack L and the collector to the other Jack L lug]]
4. Connect wire from Lug 3 of Terminal Strip to junction of R23 and R26
on circuit board. Solder this wire to lead of R26.
Keyer Keys Continuously Or
Erratically
Problems with RF causing the keyer to key continuously or erratically,
particularly when using long wire or random length antenna systems, can
be eliminated by connecting a .001 uF disc ceramic across the keyer
output jack.
Intermittent
Sidetone
In some units, if the "tone" control is turned fully clockwise [low
frequency end], the sidetone will be intermittent. Turning the pot
slightly counterclockwise will eliminate the condition.
-------------------------------------------------------------------------------------------------------------------
May 20, 1975
HD-1410 Bulletin No:
Electronic Keyer HD-1410-2
Service Guide
The following is a step by step procedure for servicing the HD-1410
Keyer:
Equipment Needed:
1 VTVM [Not a VOM or DVM]
Set controls on HD-1410 as follows:
AC Switch - ON
Speed - Full CCW
Volume - 1/4 CW
Set VTVM as follows:
To read DC + Voltage
C A U T I O N
When making voltage checks in the unit, be very careful where the probe
is touched as 110V AC voltage is present also.
1. The first test is to check the DC voltages for the power supply and
pass transistor Q8. If any deficiencies are found in this area, they
must be corrected before proceeding on.
2. The most important section in the keyer is the Dot Generator and Dash
Divider, this will be checked as follows:
With the keyer shut off, connect a jumper wire from pin 8 of IC1D
to ground. With the keyer set up in this manner, both the dot generator
and dash divider can be checked at the same time without pushing the
paddles. Turn the keyer on. Connect the ground lead of the VTVM to the
chassis of the keyer.
A. Set the VTVM to a 1.5VDC range and touch the probe to pin 10
of IC2D.
The meter should read about .16 and the needle should be oscillating
slightly. If these results are not obtained, check Q1, Q2, C3, D1 and
speed control.
B. Set the VTVM read +5VDC range and touch meter probe to pin 5
of IC4A. Reading shuld be .16VDC with needle oscillating slightly.
Check D3 and R12, if proper results are not obtained.
C. Touch meter probe to pin 8 of IC4A. Meter needle should
oscillate rapidly between 1.5 and 2.5VDC. If proper results are not
obtained, first check pin 2 of IC4A. Meter needle should oscillate
between 3.6 to 4VDC at half the rate of pin
8. Replace IC-4, if necessary.
D. Touch meter probe to pin13 of IC4B. Meter needle should
oscillate between . 5 and 3.5VDC at 1/2 the rate of test C above. If
proper results are not
obtained, check pins 14 and 3 of IC-4 for 5VDC. Replace IC-4, if
necessary.
E. Touch the meter probe to pin 12 of IC3C. Meter needle should
oscillate from 1.6 TO 3.4VDC. If proper results are not obtained, check
pin 13 of
IC3C for 5VDC. Replace IC3C, if necessary.
3. Output circuitry: Since the jumper is already installed in the bit
generator and dashes are being produced, we'll use this same approach for
checking the output circuitry.
A. Touch the meter probe to the [C] of Q4. Meter needle should
swing between .2VDC and 2.8VDC. If proper results are not obtained,
check
resistor R24. Replace Q4.
B. Touch the meter probe to the [C] of Q5. Meter needle should
oscillate between .3VDC and .8VDC. If proper results are not obtained,
check R25. Replace Q5.
C. Touch meter probe to point [J] or keyer output jack. Meter
needle should oscillate from .3VDC to .8VDC. If proper results are not
obtained,
check or replace D4.
D. Repeat the same procedure for Q6, Q7 and D5.
4. Tone oscillator circuit. Jumper will still be connected to pin 8 of
IC1D.
A. Touch meter probe to pin 4 of IC5D. Needle should oscillate
between .6 and 1.4VDC. If proper results are not obtained, check C5, C6,
tone control. Replace IC-5.
B. Touch meter probe to [C] of Q3. Meter needle should
oscillate
between 4.3 and 4.7VDC. If proper results are not obtained, check C7,
R21. Replace Q3.
5. Paddle control and memory logic: Shut off the keyer and unsolder the
jumper wire from pin 8 of IC1D.
A. Turn the keyer on and with the VTVM check the logic levels
for IC-1, IC-2 and IC-3 as shown on the schematic. With both paddles
released the logic levels will be reversed.
B. Memory bit problems can only be in IC-5, R3, R4, C1 and C2.
------------------------------------------------------------------------------------------------------------------
May 20, 1975
HD-1410 Bulletin No:
Electronic Keyer HD-1410-3
Keyer Keys Continuously Or Erratically
In the next run, a .005MFD [5000pF, PN 21-57] will be added across the
Keyer output jack.
This supersedes the information in Bulletin No: HD-1410-1
------------------------------------------------------------------------------------------------------------------- MARCH
26, 1976
HD-1410 Bulletin No:
Electronic Keyer HD-1410-4
No Dots Or Dashes
If the unit has no dots or dashes output, but has a tone in the "hold"
mode, check the installation of Q2. The customer apparenly tries to
twist the transistor so that the flat of the transistor will align with
the flat screened on the board. This will cause the base & collector
leads to short.
The manual is being changed to clarify the installation of this
transistor.
-------------------------------------------------------------------------------------------------------------------
JUNE 24, 1976
HD-1410 Bulletin No:
Electronic Keyer HD-1410-5
RFI
RFI in the keyer coming through the power supply can be eliminated by
installing two .005UFD/1.6KV capacitors [PN 21-44] across the AC line to
the ground.
--------------------------------------------------------------------------------------------------------------------
July 9, 1976
HD-1410 Bulletin No:
Electronic Keyer HD-1410-6
Wrong Type Of Round Knob
Some kits were shipped with round knobs [PN 462-932] that will not accept
the knob bushing. Although these knobs will fit onto thecontrol shafts,
the knob pointer may not align properly.
-------------------------------------------------------------------------------------------------------------------
September 23, 1977
HD-1410 Bulletin No:
Electronic Keyer HD-1410-7
Keyer Locks On Some Bands
++++Info not yet available++++
-------------------------------------------------------------------------------------------------------------------
July 24, 1978
HD-1410 Bulletin No:
Electronic Keyer HD-1410-8
No Dashes; Tone And Dots Okay
Check for a possible foil bridge between pins 8 and 9 or between pin 8
and ground of the Dash Reset circuit, IC2 [PN 443-1]. The bridge is
usually too small to see without a magnifier. The bridge usually can be
removed by scraping the area around pins 8 and 9 with a knife or other
similar object.
------------------------------------------------------------------------------------------------------------------
May 8, 1980
HD-1410 Bulletin No:
Electronic Keyer HD-1410-9
Sidetone Not Loud Enough
++++Info not yet available++++
--------------------------------------------------------------------------------------------------------------------
Thats everything I hold up to 1985 that covers the HD-1410 Electronic
Keyer
--------------------------------------------------------------------------------------------------------------------
March 22, 1985
HD-1481 Bulletin No:
Remote Coax Switch HD-1481-1
Line Cord Wiring Doesn't Meet UL And CSA Requirements
In manual [PN 595-3189], page 19 and pictorial 2-2, the line cord wiring
instructions and pictorial are incorrect. When the line cord is wired as
shown, the fuse will be in the ground [cold] side of the power line. UL
and CSA require the fuse to be in the hot side of the line. In the units
received for service, check the wiring of the line cord. The correct
line cord wiring is the ribbed lead connected to TS1, lug 5 and the smoth
lead to TS-1, lug 4.
--------------------------------------------------------------------------------------------------------------------
Thats everything I hold up to 1985 that covers the HD-1481 Remote Coax
Switch
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The above is complete as far as from the information that I presently
have available to me. If/when I get the TEB's that are missing, they
will be posted to all. Anyone that thinks that they may have missed any
bulletins are urged to check out Dales [KB9JJA] Heathkit Webpage - It has
what I have posted - plus much more helpful information - a super site!
http://members.accessus.net/~dwentz/kb9jja/heathkit/
I am getting information from several sources, which have and are being a
great help to us all. I also hope to be working on a Heath Part No.
identification list in the near future. Not enough of hours in the day
[Grin]. Happy holidays to all and best in the New Year!
73 de Joe W7LPF/4 [NNN0KUU]
QWCA - SOWP - NCVA - FISTS - RCC
Gordonsville, Va 22942 [Orange Co]
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