Sorensen  DLM300-2 need blown part numbers. - Page 1
Forum section: electronics / repair

author: R-1125F
author_rank: Regular Contributor
timestamp: June 12, 2024, 05:37:11 pm
content: I am working on an Sorensen DLM300-2 power supply. It shuts down when the voltage is turned up to 004. It looks like the OVP is shutting down when adjusted to over 4 volts. Some parts are damaged and I can’t read the part numbers. See attached photo.R385 is burned but looks like 4R? Last digit is not readable. I would like to know the value of this part.R322 looks overheated but appears to be a 22R1 or 20R1. I would like to know the exact value.Q48 is destroyed and code is not readable. Q40 is a Onsemi P1F, PZT2222AT1. I am guessing that that Q48 is the complementary PZT2907AT1. Could someone verify this?

author: fzabkar
author_rank: Super Contributor
timestamp: June 12, 2024, 06:11:07 pm
content: Can you identify Q101 and Q100? These appear to be the driver transistors. That should tell you whether the next stage is PNP or NPN.

author: R-1125F
author_rank: Regular Contributor
timestamp: June 12, 2024, 06:19:06 pm
content: Thank you.Q101 is coded as 2F (2N2907A ?)Q100 is coded as 1P (2N2222A ?)

author: fzabkar
author_rank: Super Contributor
timestamp: June 12, 2024, 06:35:55 pm
content: Those two transistors are described as complementary to each other.https://www.diodes.com/assets/Datasheets/ds30041.pdfhttps://www.diodes.com/assets/Datasheets/MMBT2907A.pdfTherefore, I think your guess for the damaged transistor is probably correct.I would think that "4R?" is most likely to be 4R7, as this is a preferred value.If we assume that this circuit is symmetrical, then R322 = R289 = 2001.

author: R-1125F
author_rank: Regular Contributor
timestamp: June 13, 2024, 02:09:35 am
content: Should that be 4.7 Ohms or 4.7k Ohms?

author: fzabkar
author_rank: Super Contributor
timestamp: June 13, 2024, 02:49:46 am
content: R denotes a decimal point, so 4.7 ohms.

author: coromonadalix
author_rank: Super Contributor
timestamp: June 13, 2024, 03:27:11 am
content: r385 seems toastedlook a like symmetry ?r288 = r321not sure if r289 is = r350 or r322WL3 ?? as the same value as R350 deductions seems right = 1002 value ? oops loll 2001 be sure to measure it

author: R-1125F
author_rank: Regular Contributor
timestamp: July 06, 2024, 01:30:17 pm
content: I got everything back together and working but with one issue. Without a load, the output transformer is buzzing. Without a load, the buzzing get louder as the voltage is increased. Under load it is quiet. While is was buzzing I tried to press on the transformer winding and the core but there was no change. As I said, there is no problem under load. Could there still be a problem that is causing the transformer to buzz without a load?

author: coromonadalix
author_rank: Super Contributor
timestamp: July 07, 2024, 07:18:08 am
content: could be some "normal" behavior since some of theses psu can be phase controlled / pwm controlled etc ... and the x-former run on light loadunless you remove it, and dip it in rosin with some vacuum air out, i would not touch iti have other brand similar psu's, and you do hear some supply noises unless it is to loud ??was it like this before the problems ?

author: R-1125F
author_rank: Regular Contributor
timestamp: July 07, 2024, 01:22:08 pm
content: I bought this as not working so I don't know how it worked before. I guess I should test it to see what the minimum load is needed to quiet down. It didn't blow up when I put a heavy load on it, so that's a good sign.