HIWATT DR 504 50 Watt Amp

got a nice piece in for a repair job, no sound the guy say,

70's Hiwatt EL-34 guitar amp,

yes those are Partridge transformers,

and darn it, the output is still good, 

but we are going to find out as much about it as we can from a non destructive viewpoint, as we do not want to ruin the $3,000 vintage resale value and get ourselves a job folding napkins in Reicker's Institute for the Criminally Insane. 

no sound? did you use the sound spray? you have to recharge those every so often like a refrigerator or hvac.

Let me guess, it's missing that one preamp  tube or is it not that simple?

yeah, probably the tube,

chassis>

...

CJ said:

yes those are Partridge transformers,

and darn it, the output is still good, 

Click to expand...

Ah, too bad! I already had high hopes when I read the thread title. Have you tried dropping it ;D.

Immaculate on the inside, always a joy to look at.

well, our prayers have been answered! while pulling back the sleeving on a primary wire to measure wire size, the wire snapped like a dry twig in a stiff desert wind,

this brittleness factor obviously means that the rest of the winds are questionable and therefore warrant a complete tear down in order that we might make this amplifier more dependable by replacing the 50 year old wire with modern materials,



edit: looking at the wire that came oiff, it is a different gauge and type, so somebody had tried a splice and that is why yhe wire popped so easy, so good thing we started poking around in there as it was a bad connection and might be the reason the amp had problems,

we had room to do the PRR method of transformer reverse engineering and received the following numbers for comparison with the tear down

1430 T Pri

94 T and 66 T for the secondary  so about 15:1 and 22:1

this makes it a 3.8K:8/16 ohm transformer or thereabouts

volker said:

Ah, too bad! I already had high hopes when I read the thread title. Have you tried dropping it ;D.

Immaculate on the inside, always a joy to look at.

Click to expand...

A friend of mine down in Florida is a huge fan of vintage Hiwatt/Marshall amps, and has done homework to build reissues:

http://royalamps.com/home.html

Check out these pix!  Look at the "Royal JPP"  series for his version of a Hiwatt:

http://royalamps.com/photos.html

IMHO, Eric's construction is waaay tidier than Hiwatt, which I always thought was beautiful.

Bri

Thanks so much for the links!   

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