HW-101 blows power supply breaker after a minute or two.

Discussion in '"Boat Anchor" & Classic Equipment' started by N6ECI, Oct 28, 2012.

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  1. N6ECI

    N6ECI Ham Member QRZ Page

    My trusty HW-101 has worked fine for decades but now this problem: Sometimes when you turn it on the power supply breaker blows in about a minute or so. If the breaker does not blow, a rather unpleasant smell begins to come from the radio, not the power supply. Suggestions?
  2. K7KBN

    K7KBN Ham Member QRZ Page

    First: Disconnect all leads. Open it up, look for obvious signs of overheating.
    If none: Reconnect power and turn it on, looking for source of smell.

    Then: Fix.
  3. AD4DQ

    AD4DQ Ham Member QRZ Page

    Something is pulling too much current.... hard to say.... an unpleasant smell is something burning. I would visually inspect
    every wire, contact, switch and tube, looks for possibly burnt resistors too. Good luck.
  4. KE3WD

    KE3WD Ham Member QRZ Page

    It could be something inside drawing excess current and tripping the old thermal breaker -- or it could be the old thermal breaker is in need of replacement.

  5. KO6WB

    KO6WB Premium Subscriber QRZ Page

    Usually the smell would trump the old breaker as being bad. It's time to get out the old construction manual and start looking for the problem(s). As a test you could disconnect the high voltage line in the power supply and put a milliamp meter in line with the low B+ line and see if that is the cause of the problem. If it doesn't pull high current and the high voltage disconnect doesn't stop the breaker from tripping then just about the only thing left is the filament circuit.
    If you lost the manual for the HW-101 then just download it from the net. It's actually there and free.
    Hope this helps
  6. KE3WD

    KE3WD Ham Member QRZ Page

    I've repaired many an old appliance that used the then-ubiquitous red button thermal breakers, and in many cases, the things would indeed smell because internally they contain basically a wirewound resistor in series with a set of contacts.

    Pitted, burned or corroded contacts here can indeed contribute to a smell.

    But of course the troubleshooter should always first ascertain the basics, measure current draw and see if it is in spec, look and also feel sometimes for burned, slightly burned or otherwise out of spec components, use the variac and the series lightbulb if necessary on the testbench.

    Just wanted to point out that these old thermal breakers can and do go bad.

    And can and do release that smell of something overheating, as well. not always, but...

  7. W9GB

    W9GB Ham Member QRZ Page

    Mike --

    IF your Heathkit HP-23 power supply is all original parts (now ~45 years old), this may be a good opportunity to repair/refurbish/update that external HV power supply. This will give you a baseline of "good HV DC power" to your HW-101 transceiver.

    Heathkit HP-23 Rebuild -- WB2VSJ

    Plenty of GOOD electronics parts suppliers with paper and Internet (on-line) catalogs.
    (Mouser, DigiKey, Allied Electroncis, Newark Electronics, Future Electronics).

    Hayseed Hamfest is a GOOD source, if you desire vertical electrolytic can replacements
    for your HP-23(A). Contact them at their web page.

    WD5DZG rebuild of HP-23

    Another source option is Mike Bryce, WB8VGE from "The Heathkit Shop"

    Mike sells an "HP-23RL" rebuild kit consisting of a PC board and all new components to rebuild
    your Heathkit HP-23(A) HV supply.
    A new circuit breaker is not part of Mike's kit, but are available from these sources:

    Old Heathkit Parts - K8GNZ

    Common mfg. for the circuit breaker:
    Tyco, Schurter, Carling Technologies,

    TA Weber, Photo of their breaker

    Catalog page of circuit breakers and fuse holders

    THEN with the HW-101 disconnected from power -- perform a careful visual (eyes) and smell (nose) to determine IF the burnt component is easily identifiable. You can also use a VOM/DVM/VTVM to check resistors or suspect connections.
    Last edited: Oct 28, 2012
  8. W5RKL

    W5RKL Ham Member QRZ Page

    Based on what you have said, I doubt the power supply is the source of your problem. However, you can test the power supply quite easily.

    Remove the power cable between the HW-101 and the power supply. Pull the power supply's main power cable from the wall outlet. Place the power supply's toggle switch in the "center" position. Short/jumper pins 9 and 10 on the HP-23 power supply's 11 pin socket. Plug the main power cable into the wall outlet and flip the power supply's toggle switch to 250VDC
    side. If the breaker does not trip and you don't smell anything bad or see smoke rising from the supply then the supply is not the source of your problem.

    You can now measure the power supply voltages at the following power supply 11 pin socket pins as follows, using pin 7 as ground:

    1. -130VDC (Bias)
    3. 250VDC (LV, changes to 350VDC with the toggle switch set to 350VDC position)
    4. 820VDC (HV)
    11. Adjustable bias, not used with the HW-101. Vary the pot on the front of the power supply should result in the voltage rising and falling depending on the position of the pot.

    Measure the power supply's AC filament voltage as follows: (note: set your volt meter to measure "AC" voltage)

    Measure the filament voltage between pins 2 and 6 which should be 12VAC.
    Measure the filament voltage between pins 2 and 8 which should be 6.3VAC
    Measure the filament voltage between pins 6 and 8 which should be 6.3VAC

  9. K9STH

    K9STH Ham Member QRZ Page

    Only the HP-23 and HP-23A had variable bias. Also, those are the only ones that had 6.3 VAC. The HP-23B, HP-23C, and PS-23 had only 12.6 VAC and no variable bias.

    In addition, the original HP-23 has the 250 VDC and 300 VDC hard wired. That is, there is no external switch to change the lower B+.

    The PS-23 is the same as the HP-23C. However, after Hewlett-Packard ended up owning Heath, they did not want "HP" as part of a Heath model number. Therefore, the nomenclature was changed to PS-23.

    Glen, K9STH
  10. W5RKL

    W5RKL Ham Member QRZ Page

    I agree with you Glen.

    Quite often postings do not always have the exact model number such as in this case Mike did not state which exact model supply he had. The only supply indication Mike gave was when he referred to "the power supply
    breaker blows"
    . Therefore, to my knowledge, that comment narrows it down to only 2 possible supplies, the HP-23A or the HP-23B since they are the only 2 Heathkit HP-23 supplies that have the breaker. In addition, to my
    knowledge, the HP-23A and HP-23B are the only 2 HP-23 power supplies that have the 3 position toggle switch. As you have said and I agree, the HP-23, HP-23C and PS-23 do not have the toggle switch for selecting the LV output
    voltage level, they all have hardwired LV output, based on which "Heathkit" transceivers the supply will be used with such as the HW-12, HW-22, or HW-32 monobanders which use the 250VDC LV output while the HW-100, HW-101,
    and the SB-100-102 use the 350VDC LV output. I could be wrong but I believe the PS-23 supply, the last of the HP/PS-23 supplies Heathkit marketed, was used to power the Heathkit HX-1681 HF transmitter.

    I agree, the HP-23 and HP-23A are the only supplies that have selectable filament voltages and variable bias output (pin 11 variable bias output). The others, HP-23B, HP-23C, and PS-23, all have 12VAC only
    filament voltages and only fixed bias. But, again, since Mike didn't state which supply he has, I included the filament and variable bias statements.

    In short, Mike will have to visually inspect the supply using the supply's manual and schematic as a guide, to determine the voltage and switch options his supply has. Mike also didn't state whether he has the power supply and/or the
    HW-101 manuals or not. If Mike doesn't have either manual then I would recommend he purchase/obtain both manuals before attempting to troubleshoot both the supply and the transceiver.

  11. K9STH

    K9STH Ham Member QRZ Page

    The HP-23 does not have a circuit breaker. It uses the "suicide" plug, that is, the one with fuses in the plug. However, the HP-23 does have a pilot lamp whereas the remainder do not.

    Since the power supply in question has a circuit breaker, it would have to be an HP-23A, HP-23B, HP-23C, or PS-23. That, I "missed"! If it has the LV switch, then it would have to be an HP-23A or HP-23B. Then, if it has the adjustable bias, then that narrows it to the HP-23A.

    Glen, K9STH
  12. K8ERV

    K8ERV Ham Member QRZ Page

    Or me between showers.

    TOM K8ERV Montrose Colo
  13. WB2WIK

    WB2WIK Premium Subscriber QRZ Page

    Sounds to me like it's a problem in the rig and not in the PS. That's where the smell is, and nothing in the PS needs to warm up; he said it blows after a minute or two, which sounds like it's part of a tube circuit since they do take time to warm up.
  14. AD4DQ

    AD4DQ Ham Member QRZ Page

    Confusing.... im pretty sure mine is a regular HP-23. It has the fused plug, HV and LV switch and pilot lamp on it and adjustable bias.
  15. K9STH

    K9STH Ham Member QRZ Page

    If it has the fused plug and the voltage switch, then it is an earlier HP-23A. None of the HP-23 have a voltage switch.

    Before you do anything else, replace the 2-wire cord with a 3-wire cord (connect the "green" wire to the chassis) and install a fuse holder inside the chassis (there is plenty of room) in the black wire coming from the 3-wire cord through the fuse to the AC off/on portion of the toggle switch. The white wire goes to the "other side" where the 2-wire cord was installed.

    Radio Shack has some suitable fuse holders that can be installed either using a machine screw or double-backed tape.



    I use these fuse holders to add fuses to older equipment that do not have a fuse.

    Glen, K9STH
  16. K8AG

    K8AG Subscriber QRZ Page

    HW101 trips breaker. Smells.

    Hi Mike,

    Don't forget that a high resistance contact can also generate heat. You may find that a relay contact has a less than optimal resistance. The smell could be burning from inside the relay. Any voltage you can measure across what is supposed to be a closed contact would be a symptom.

    Had a 100 many many years ago. Don't remember much specific about it. Great rig though.

    Hope you find the problem.

    73, JP, K8AG
  17. N6ECI

    N6ECI Ham Member QRZ Page

    Hey All --
    Thanks for the replies and suggestions. Just an update. (Still looking for the problem.) The power supply is indeed the HP-23B, with the big red "reset" button on the breaker. I did test all voltages coming out of the ps and everything looked pretty close.
    I had recently re-tubed the whole rig except the finals and the OA2, so I put a bunch of the old tubes back in...same result. The breaker usually kicks off after a minute or so. In the event the breaker does NOT trip, then the "burning-something" aroma comes from the radio (not the ps). Visually, can't see anything amiss.
    Taking this slow as time allows. Next is the check on B+ current. Someone mentioned filament issues...what could be going on there? Thanks.
    Mike N6ECI
  18. KE3WD

    KE3WD Ham Member QRZ Page

    Locate the general area of that burning smell...
  19. W5INC

    W5INC Ham Member QRZ Page

    Why did you re-tube the whole radio? Did the radio work when you got it, know it's history of use? Did you put back "all" of the old tubes in the radio and still have the breaker blow? Have all of the the "new" tubes been tested good recently on a good tube checker?

    I would go back to square 1 and put back all of the tubes that came with the radio to start out with. When replacing all of the tubes in a older rig you will throw off the alignment if nothing else. You can also destroy a prefectly good new tube by plugging it into the bad circuit before finding the problem in the rig. The tubes might/might not be the problem, but no sense in taking a chance in wasting a good tube, IMO.

    From a Zed member far wiser then myself in fixing older radios, so you can write this in granite so to speak.

  20. KA0AAM

    KA0AAM Ham Member QRZ Page

    check your relays. they should be approximately 5000 ohms across the coils. also take the cover off of your final cage and see if your finals are glowing just before your power supply goes out; your finals may be going into oscillation.
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