SUCCESSFULLY REPAIRED-Hameg hm5006 - Page 1
Forum section: electronics / repair

author: vlelectroniclab
author_rank: Contributor
timestamp: October 05, 2024, 07:53:08 pm
content: hello everyone,could someone help me with this hameg hm5006 spectrum analyzer?basically this instrument fell and did not turn on anymore, I disassembled the power supply and replaced the tda4506 and after many attempts it turns on and works for a couple of hours.I turn it off and on again and I hear a bang, I disassemble the power supply board and find acid on it, so I replace all the capacitors but nothing, it turns on late and the screen does not work anymore.I attach the manual.thanks in au.

author: Harry_22
author_rank: Frequent Contributor
timestamp: October 06, 2024, 01:07:06 pm
content: Hi!Have you checked the voltages acoording to service manual?Please be careful there is 2 kV present here!Could you make a good photos of PS.

author: vlelectroniclab
author_rank: Contributor
timestamp: October 06, 2024, 01:11:29 pm
content: hi,thanks for the reply.i checked the voltages and they are 0v when it does the fault.after several attempts to put and remove the plug it turned on, i measure the voltages and they are all ok as the manual says.the cathode ray tube does not turn on anymore while all the other things work.

author: Harry_22
author_rank: Frequent Contributor
timestamp: October 06, 2024, 01:50:13 pm
content: Check the voltage on pin 6 TDA4605 when PS does fault.It must be above 12(13max) VDC to turn PS on.Also check voltages on C1017 and pin 3 TDA4605.

author: vlelectroniclab
author_rank: Contributor
timestamp: October 06, 2024, 02:19:11 pm
content: PIN 6 11,8v don't work, 12,4v workPIN 3 0,5v don't workTomorrow view other measure

author: Harry_22
author_rank: Frequent Contributor
timestamp: October 06, 2024, 07:15:26 pm
content: The controller TDA4605 is locked with a latch of T1009, T1011 transistors.This is indicated by the low voltage 0.5V on pin 3. (T1009 shorts pin 3 via R1059)A low voltage on pin 6 indicates that the controller is leaving the switch-off state but does not start up because it sees "mains undervoltage" via pin3.The latch is switched on by the high current via sense resistor R1015.If your PS turns on after several attempts to put and remove the plug that means it isn't shorted but little bit overloaded.Try to disconnect PS from SA and test it for instance with 100 Ohm 6W load between +12V and -12V rails.Be careful with P1010 connector!

author: vlelectroniclab
author_rank: Contributor
timestamp: October 06, 2024, 07:51:53 pm
content: hi,i removed the power supply from the instrument and started everything and it has the same problem.i checked all the current detection part, the two transistors, the resistors and the capacitor and all the components are good (to check them i unsoldered them).i did a trivial test, instead of 220vac i gave it 24vdc with the positive that powers r1019.on pin 3 i put another power supply and gave it about 2v and i heard a buzz, all the voltages are ok.after this could the tda be faulty?

author: Harry_22
author_rank: Frequent Contributor
timestamp: October 06, 2024, 08:19:52 pm
content: Good job!You can connect 100k in parallel with r1050, r1048 to get 2V at pin3.TDA is Ok.Check C1040, C1041. They provide a soft-start delay.

author: vlelectroniclab
author_rank: Contributor
timestamp: October 21, 2024, 07:52:54 pm
content: hi,sorry if I didn't update you, but unfortunately I didn't have time to do other tests.c1040/1 are good.i tried to put the 100k resistor but the voltage is always low, it seems like the tda pin absorbs too much current...i had a doubt what is the difference between the tda4605-15,tda4605-2,tda4605-3?Thanks Vito

author: vlelectroniclab
author_rank: Contributor
timestamp: October 29, 2024, 12:32:47 pm
content: Hi,Finally I solved the problem.To be safe I tried another tda but nothing worked. then I increased the voltage at pin6 of the tda to 12.3v with a power supply and magically it turns on.I replaced the R1030 with a 470R and now it works perfectly, it starts on the first try and the voltages remain perfect.From what I understood is that someone had changed the original TDA4605 with a TDA4605-15, it just absorbs a few more mA and the supply voltage does not reach the starting threshold.Regarding the display that no longer worked I adjusted the contrast via R1003-R1004 and it appeared.All in all I have to say that it is a good tool for the timeI will use it mainly to see if the 433mhz radio controls work and for now it is enough for me.Thanks to all of you for the tips.