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dbt

  1. R

    Dim Bulb Tester Question

    So I'm still relatively new to working on these older amplifiers and such but I always want to make sure I get things done right. I've been working on and diagnosing an issue with a Pioneer M-90a I imported from Japan. Evidently the predrivers have failed and everything down the board is getting...
    • Rotary
    • Thread
    • dbt diy repair restore
    • Replies: 2
    • Forum: DIY
  2. R

    Sansui 990DB bias / trimpot issue

    Greetings AK friends, Some background for context: I am fully restoring a 990DB. During the process, and testing along the way, replacing the bias/offset trimpots on the driver board caused the DBT to 'pulsate'. I came across a Youtube of this guy who faced the same issue and pointed towards...
  3. dlucy

    dlucy's guide to Dim bulb testers, Variacs and autotransformers

    Following is a convenient collection or compendium of information and posts from elsewhere on AK and therefore from many different members. Where possible, the posting member has been credited and the source thread or post has been linked. Corrections and additions (and updates to modern info)...
    • dlucy
    • Thread
    • autotransformer dbt dim bulb tester dimmer variac
    • Replies: 20
    • Forum: Test Equipment
  4. R

    DBT faint but never unlit.

    Hello, i have Marantz 1180dc, power it up with DBT. Before i make a thread in Marantz sub forum but its different story, but maybe i was in the wrong subforum, is it ok to make new thread here? Full story is in here...
  5. sabrefencer

    Dim Bulb Tester - Incandescent Bulbs going away in USA

    Sale of incandescent light bulbs will be banned in the US as of July 31, 2023. This is bad news if you use a dim bulb tester (DBT) for powering up potentially shorted equipment. Other countries may have already done away with them. I use an assortment of 60, 100, 150, and 200w clear...
  6. Refugee

    Another dim bulb tester build

    Dim Bulb Tester Build First, What is a dim bulb tester? It is a current limiting device. It is used to protect a device that is in unknown condition or suspected of not working for any reason. If the device under test (DUT) has a short, the device will be protected from drawing too much...
    • Refugee
    • Thread
    • bulb cigar box current limiter dbt dim bulb test dim bulb tester project box safety test test eqipment
    • Replies: 5
    • Forum: DIY
  7. D

    Need some input on Dim bulb tester behavior

    Hi I recently acquired an Vintage Harman Kardon HK560 that behaved a bit different upon testing it on my DBT: Start bright, goes dim but after 5-10 seconds starts to light up until it is maybe 50 or 60% bright, not really full bright. Is it safe to power up without DBT or is there an indication...
    • Donguri
    • Thread
    • dbt drifting bias hk 560 hk560
    • Replies: 83
    • Forum: Solid State
  8. AlexHempel

    DIY panel for testing amps (DBT+Variac+Ammeter etc.)

    In the past, I've always configured my amplifier test rig using alligator clips, but I figured I should create a hardwired setup. I want to be able to switch the DBT and variac in and out as necessary; when they are bypassed, they should be fully deenergized and entirely removed from the...
    • AlexHempel
    • Thread
    • dbt variac
    • Replies: 12
    • Forum: DIY
  9. Richs_Trains

    Marantz 140 amp DBT dead short question

    Hey all, I have a Marantz 140 amp that I replaced some diodes on several years ago because the peak indicators were stuck on. After this fix, the unit worked fine and I had it in the living room on a 3200 for several months with no issues. A couple of years ago I swapped the unit out for a...
  10. FireGuruMN

    Bucking Transformer in a Box

    I have a variac on my bench and a bucking transformer also on my bench for when I am listening to a tube amplifier while restoring another project. I don't like to use the variac all the time because it buzzes and I use it too often on whatever I am restoring at the time. So I wanted to build...
    • FireGuruMN
    • Thread
    • bucking transformer dbt dim bulb tester variac
    • Replies: 8
    • Forum: Tube Audio
  11. klamsoss

    Variac powered, fused, dim bulbed, and metered, switched bench power?

    Good morning race fans! Relative newbie looking for some input on a DIY bench power monitoring station... I have been working on tube gear for a year or so and the variac is a great tool. I have a 15A staco unit that weighs enough to use it for home defense. I also put together a DIY AC meter...
    • klamsoss
    • Thread
    • bench dbt dim bulb tester meters testing variac
    • Replies: 26
    • Forum: DIY
  12. G

    SX-850 failing DBT and no relay click after work on Power Amp

    Hello Everyone, continuing work on the SX-850. I rebuilt the power supply and updated caps and transistors on Protection circuit and EQ board, was working fine after that. I then swapped out the electrolytics and transistors (other than the output transistors attached to heatsink) on the power...
  13. ghazzer

    Calculating voltages when using a DBT?

    Assuming that a receiver/amp is working correctly, no input, and the volume is at zero, is there any way to calculate (approximately) the power supply and rail voltages when connecting it through a DBT? I know that this would be very helpful to me, just as an indicator of relative health. It...
    • ghazzer
    • Thread
    • dbt
    • Replies: 17
    • Forum: DIY
  14. W

    Need help understanding behavior of DBT

    Hi I am trying to revive a NAD 7220PE. When I first powered it on via a Dim Bulb Tester, the bulb glowed dimly. Then I checked the 4 4A fuses and found that all of them had blown so I replaced them. Now, the bulb glows brightly indicating that the NAD has a short (and nothing sparked or blew, at...
  15. Richs_Trains

    4230 DOA Amateur Needs Help

    Hey All, My newest project came in sad shape with the power cord cut off and a monster fuse in the fuse holder. It is a Marantz 4230 Quad unit. I put a new cord and proper 3a fuse and put it on the DBT. I get a bright light and no power in the unit (I don't know if I should get anything if...
  16. Richs_Trains

    Marantz 1040 DBT stupid question

    Hey all, Got a 1040, again, bought it for the wood case, but figured I'd check it out. Being new to all this, I am still learning. When I connect it to a DBT, it passes, until I engage the speaker switch, then I get a bright bulb. I never left it on long enough to see if there is sound as I...
  17. pioneerhip

    Pioneer SA-9500 No relay click

    Thanks for the help in advance. With the amp hooked to the DBT and all adjustments set the relay clicks on and it plays. When i plug it into the wall however no relay click. I connected to the wire wraps again with the voltmeter and reset the bias/dc off set and nothing? So where do i start now?
  18. Hyperion

    OK, I did it...

    I ordered TEN 100w incandescent bulbs from Amazon just for my DBT. There I said it.
    • Hyperion
    • Thread
    • bulbs dbt
    • Replies: 33
    • Forum: DIY
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