Salvage Philips HTS3520 - Page 1
Forum section: electronics / repair

author: vidarr
author_rank: Frequent Contributor
timestamp: February 05, 2025, 04:03:09 pm
content: Hey guys. I got the service manual for the Philips HTS3520 to troubleshoot what's wrong with it. The unit turns on and I can cycle thru all of the input sources, but it doesn't output sound.The manual says to check/measure the +42V of XP703 on the am board. The value is 33V. The manual doesn't mention if the voltage can vary. Is this a problem? Or can the 33V power the amp board?Also, the dvd player is gone. Could this also be a problem?Thanks!edit: If the XP703 voltage doesn't check out, the next step is checking the 3.3V on #7 pin of XP1. It is reading 3.1V, not 3.3V.https://www.manualslib.com/manual/922979/Philips-Hts3520-12-05.html?page=37#manual

author: benj38
author_rank: Frequent Contributor
timestamp: February 06, 2025, 08:16:39 am
content: 33V instead of 42V is too low. 3.1V instead of 3.3V is a bit on the low side (usually about 5% variation is fine) but I would still consider it OK for the purpose of the troubleshooting flow chart.

author: vidarr
author_rank: Frequent Contributor
timestamp: February 07, 2025, 01:44:29 am
content: The next step in the flowchart (if the 42V that is required is not the case) says:"Check the 22pin FFC connection and XS702 is fixing OK between the main board and am board".What does "is fixing OK" mean?The connection is solid. Plugged in properly. The connector is in great shape.I don't know what this "fixing" is.THANK YOU!

author: benj38
author_rank: Frequent Contributor
timestamp: February 07, 2025, 07:41:52 am
content: You are following the flowchart wrong. From the first box you should go right, along the arrow marked "no", since you do not have 42V., then from the second box you should go down along the arrow that says "Yes" since you do have the 3.3V (as I said before, 3.1V is close enough for this purpose).

author: vidarr
author_rank: Frequent Contributor
timestamp: February 07, 2025, 02:48:48 pm
content: Not sure why I went that way on the flowchart. But, now, going thecorrectway on the flowchart, I don't understand what comes next either. I don't know what this means:"Refer to Power supply board part"Not sure what "board part" is. I know what a "PS Board" is, of course. Looking thru the manual, I don't see a flowchart for the PS board. This may be an ESL language problem? There are circuit diagrams for that board, but nothing I see that can help me troubleshoot it.Thank You!

author: benj38
author_rank: Frequent Contributor
timestamp: February 07, 2025, 04:00:28 pm
content: Quote from: vidarr on February 07, 2025, 02:48:48 pmThey mean that you should refer to the schematic diagram of the power supply (page 46), at which point you are on your own as far as the manual is concerned.However, looking at the schematics, it looks likethere is an inconsistency in the manual!There is a 6 wire connection between the amplifier board and the power supply board: on the amplifier side they write that 3 pins are ground, and 3 pins are +42V (which is also the voltage they specify in the flowchart you are using), whereas on the power supply side they say that these pins are +32V!Given that you measured +33V, I would say the +42V is a typo, and that +32V is the correct value, which means that this voltage is fine in your instrument (+33V is well within tolerance for +32V spec.)In other words, you should indeed continue in the flow chart down from the first box following the "yes" edge.Quote from: vidarr on February 07, 2025, 01:44:29 am"Fixing OK" is their funny way of saying that it is mechanically well connected, which you say it is. So, in conclusion, you should now follow the flowchart further down along the "yes" edge to the box that says "Check whether the control signal is..."

author: vidarr
author_rank: Frequent Contributor
timestamp: February 07, 2025, 10:02:00 pm
content: Awesome that you caught that 32V - 42V thing! Otherwise, having no serious attachment to this piece of equipment, I would probably have thrown in it the garbage.Thank you so much! Moving on to the next steps in the flowchart.