Hiwatt Gurus: Help your friend Bob!

[Dr.HI-TONE]

-40 is "o.k." for pin 5 labelled #2
60 is WAY low for #1 it should be in the 460-480vdc range

this should help: Voltages from DR504 #4112 I will email you the full table of all the voltages. You can compare them to what you have and isolate the faulty/fried component.

power tube voltages.
3 481 3 480
4 469 4 469
5 -35 5 -35
6 480 6 477
7 3mv 7 3mv
8 8

Electrolytic capacator Voltage
16+32 50+50 200uf 200uf 200uf
16 333 50 468 pos 245 pos 480 pos 239
32 364 50 477 neg 0 neg 239 neg 0
neg neg 246

when I try to paste it here, it bunches it all up.

[OldSchoolDave]

when I try to paste it here, it bunches it all up.

The forum software parses "unnecessary" spaces . How's this?

DR504 Voltage Example reduced.jpg (44.83 KiB) Viewed 2745 times

[Dr.HI-TONE]

Thanks Dave!
I have emailed the full table to HIWATT Bob. Hopefully it will help isolate and identify the faulty/fried component!

[mhuss]

Based on those voltages, it seems like you're still on Standby. If the HT fuse is good, perhaps the Standby switch failed. With the amp off, measure the continuity between the bottom and top standby switch terminals. Should be 'infinity' off and close to zero ohms on.

--mark

[Hiwatt Bob]

Based on those voltages, it seems like you're still on Standby. If the HT fuse is good, perhaps the Standby switch failed. With the amp off, measure the continuity between the bottom and top standby switch terminals. Should be 'infinity' off and close to zero ohms on.

--mark

i will try this--

actually this sounds like a possible answer! it happened right after i switched it on, it was loud for a split second--then it sounded exactly how it sounds when you continue playing after powering the amp down.

hoping this is the case.



Also, thanks a ton Clayton--i got the excel table. i assume when you measure these points it's between ground/chassis and the turret/solder point (like mark explained above)? sorry guys, i'm a n00b and have never really measured component values, etc.

[Dr.HI-TONE]

You are Welcome!
indeed the black connected securely to the chassis and the red probe to the turrets etc. put your other hand in your pocket or behind your back, you do not want to contact the chassis!

[Hiwatt Bob]

You are Welcome!
indeed the black connected securely to the chassis and the red probe to the turrets etc. put your other hand in your pocket or behind your back, you do not want to contact the chassis!

will do Doc.

hopefully it's just the standby switch--but even if it is, i'm going to check my component values, just to make sure everything's up to snuff.

[Dr.HI-TONE]

I am hoping for the switch!
and no soiled shorts!

[Hiwatt Bob]

i'll diaper up just in case.

[Hiwatt Bob]

mark,
i hope i did it right--there are a total of 6 points on the standby switch, 3 on each side. i measured between the top and bottom on both sides (and diagonally, since those were the ones that had wires; also one of the middle points had a wire). anyhow, i set the multimeter to every ohm setting and got an OL (overload) reading across the board, both with the switch on and off. made no difference. do you think that means it's a bad switch?

[Dr.HI-TONE]

it's telling me the switch is shot.

[mhuss]

Odd, that sounds non-original. In any case, with a DPDT (six-terminal) switch, you need to measure from the center lugs to the outside ones. It should measure OL on one end and zero on the other end, and this condition should reverse when you flip the switch.

Looking from the back:

Code: Select all

A1  A2
B1  B2
C1  C2

When the switch is down, A1-B1 should be zero and A2-B2 should be zero. All other connections should be OL.
When the switch is up, B1-C1 should be zero and B2-C2 should be zero. All other connections should be OL.

--mark

[Hiwatt Bob]

alright, so i've gone and done it now.

i was feeling brave (and impatient) and i hooked up a jumper wire to try and bypass the "bypass" switch. i know, i'm an idiot. it started making a humming sound (phsycially--NOT through the speaker) and the mains fuse blew. i removed the jumper wire--and tried a new fuse and it at least lit up.

any idea what that humming sound was?

also--i haven't changed the fuses since i bought the thing, so i don't think i ever checked them. but there had a 125V 5A "MDX"? fuse in there, looked odd. i read on mark's site it should be a 1A (HT) and 3A (mains), so i picked up some of those today.

i'm thinking of just bringing it in to Savage Audio tomorrow and letting the pro's figure it out.

[gldtp99]

Low voltages and loud humming/blown fuse suggest power supply fault---- check for blown rectifier diode(s) and/or bad filter caps.....................gldtp99

PS-- if you're not sure how to do these checks--- then by all means take it over to Savage

[mhuss]

When a power transformer is badly overloaded, it hums loudly. Sounds like your amp needs some service.

--mark