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Finished Harmony Amp Project!!!

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6/14/2000 9:00 PM

Finished Harmony Amp Project!!!

I just finished replacing the filter caps in my 1950's Harmony amp (Model H189). I already replaced the power cable (with a grounded one) and the speaker, and I could not stand the hum any longer...
This is a very small, single-ended amp similar to a Fender Champ. The tubes are: 35Z5 (rect.), 50L6 (o/p) and 12SQ7 (pre.). VERY CUTE!!!
One question though. I had to replace the original "Pyramid" brand filter cap with 3 smaller radial caps. The original was pretty much shot...
I do not like to alter original designs, so I placed the new caps inside the metal housing where the original cap had stayed. My electronics wholesaler said that an original replacement type is not available. Is this true, or does someone still make these???
The leads on mine are as follows:

RED 40 MF @ 150V
RED 40 MF @ 150V
BLUE 20 MF @ 25V
BLACK common(-ve)
Part #925061
Casing #472348

BTW this little guy sounds great!!!

Regards,
Glen H.

6/14/2000 9:19 PM
SteveG	I wouldn't swear that no-one makes them, but I gave up trying to find one for a little Selmer combo recently. Looks like you've hit on a reasonable compromise to me.

6/14/2000 9:24 PM
PTJohn	You might try Antique Electronic Supply in Tempe, AZ. Not Spamming for them, but they do have one-sies and two-sies occasionally. It's probably worth a shot. www.tubesandmore.com.

6/15/2000 2:32 AM
Graywater	Glen, Obviously, this is a line connected amplifier, at least the heaters. If there isn't a separate B transformer you need to acquire, or make, an isolation tranny to prevent shock if you encounter a grounded object and your amplifier is phased wrong. This subject has bee broached numerouse times on Ampage - let us know if you need tips. GW

6/15/2000 4:11 AM
Glen H.	I have the amp properly wired and grounded (3-prong), and have not been zapped when swapping between my guitars/amps. But what if another amp or PA system is not wired (phased) properly? Could the exchange be lethal? Glen H.

6/15/2000 11:02 AM

Glen,

Very lethal - if you've ever gotten across 120v and couldn't let go (I fell and broke the current path) you will not forget it!! Any inproperly grounded outlet (your frig, maybe)or non-grounded outlet and the equipment plugged into it constitute a shock hazard with you amp.

Now, when I build I love line-connected heater strings - seems a waste of power tranny to power heaters and there's lots of great NOS series string tube available out there. Still, I don't ground the heater string and I use an isolated "B" supply for safety sake. You know, this can be as easy as two surplus trannies with 120v primaries connected "back to back" to create an isolated 120v supply - especially is you're only running the "B" supply which draws little current.

GW

6/15/2000 5:58 AM
Casey4s	Is the multisection cap you are looking for a "twist Lock" type? I found you a 40+40+20 @150v in a Sprague # PCL3439 1"x2" NOS $1.53. The 20 mf is at 150v instead of 25v, but going up in voltage won't hurt anything as far as I know. Casey4s

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