HW-101 blows power supply breaker after a minute or two.
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?
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.
Semper ubi sub ubi. 73
K7KBN CWO4 USNR Ret.
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.
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.
Originally Posted by N6ECI
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
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...
Originally Posted by N6ECI
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 by W9GB; 10-28-2012 at 04:32 PM.
Nullius in verba
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.
Originally Posted by N6ECI
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
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.
I agree with you Glen.
Originally Posted by K9STH
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.